Category: Biology

Introduction

Any living organism’s fundamental structural and functional unit is its cell. In any living organism, cells serve a variety of important tasks in terms of growth, development, and daily activities. They perform these activities through chemical processes that take place inside specialized structures called cell organelles. Eukaryotic cells without a cell wall are referred to as animal cells. Since these cells are eukaryotic, they exhibit the existence of membrane-bound organelles as well as a well-defined nucleus that is protected by a nuclear membrane. It has been noted that animal cells are smaller than plant cells. According to their role in the animal body, they also exhibit a wide variety of sizes and shapes.

Learn More about Animal Cells. Check out more videos in Science Class 8, Lesson 8 – Cell-the unit of life.

Animal Cell Organelles

Cell Membrane

• It is a unique structure that encircles the animal cell and gives it structural stability.
• It controls the movement of various molecules in and out of the cell.
• The characteristic property of the cell membrane is selective permeability.
• A phospholipid bilayer, as well as many kinds of specialized proteins, lipids, and carbohydrates, make up its structure.
• The cell membrane is termed “amphipathic” because the phospholipids of the cell membrane have a hydrophilic head and a hydrophobic tail.
• The cell membrane also plays a critical role in shielding the cell from the outside environment.
• Specialized proteins termed transport proteins aid in the transit of polar molecules through the cell membrane.

Nuclear Membrane

• It can be described as the nucleus’ outer boundary.
• It is the membrane that confines the nuclear area from the cytoplasm It is a double-membrane structure.
• It protects the genetic material from chemical reactions that take place in the cytoplasm.
• The movement of materials into and out of the nuclear area is controlled by the nuclear membrane.
• It consists of nuclear pores, which are points of entry into the nucleus. 
• These nuclear pores assist in the transportation of material and help in regulating their movement.

Nucleus

• It is frequently referred to as the cell’s “control center.”
• It is the area where the cell’s genetic material is kept and is in charge of controlling daily cell functions and multiplication.
• It is made up of the nuclear membrane, the genetic material, chromatin, nucleolus, and nucleoplasm.
• The production of ribosomes takes place in the nucleolus.
• DNA, which makes up chromosomes, contains instructions for cell division and growth.

Centrosome

• Animal cells only have these organelles, which are missing from plant cells.
• During cell division, they serve as the main organizing unit for microtubules.
• They are made up of two centrioles, which are two groups of microtubules that are kept perpendicular to one another.
• The development of spindle fibers, which bind to chromosomes in the metaphase and move them toward the poles in the anaphase, is aided by these cells.

Lysosome (Cell Vesicles)

• It is frequently referred to as the cell’s suicide bag.
• These membrane-bound organelles are crucial for breaking down big molecules and eliminating waste from the cell.
• It has an acidic pH and a wide variety of hydrolytic enzymes that aid in its function in the disintegration of molecules.
• Lysosomes develop as budding from the Golgi body, whereas the endoplasmic reticulum makes the hydrolytic enzymes.

Cytoplasm

• It refers to the thick liquid that envelops cellular volume.
• The cytoplasm, includes the cytosol, various organelles (apart from the nucleus), and other macro- or macromolecules.
• The majority of cellular responses and metabolic processes take place there.
• It serves as a matrix in which the other organelles are suspended.
• The fluid nature helps molecules flow more easily inside cells.

Golgi apparatus

• In the Golgi apparatus, molecules created in the endoplasmic reticulum are packaged, modified, and transported to their final location.
• The molecule that has to be delivered is contained in vesicles made by the Golgi system.
• It has two primary faces: the forming face, also known as the cis face, where vesicles attach to be modified in the Golgi cisternae, and the mature face, also known as the trans face, where the vesicles are released.
• Lysosome synthesis is also carried out by the Golgi apparatus.

Mitochondrion

• These are frequently referred to as the “powerhouse” of the cell since they participate in ATP creation.
• This organelle is referred to as a semi-autonomous organelle because it has its own DNA.
• Within this organelle, cellular respiration occurs to finally produce energy.
• It also plays a role in apoptosis, cell communication, and signaling. Other activities include the storage of calcium ions to maintain a balance of calcium ions in the cell.

Ribosomes

• They are small organelles that are not membrane-bound.
• They are mostly located in the mitochondrial matrix, the nucleus, and the cytoplasm.
• They serve as the main location for the synthesis of protein.
• It typically has 2 subunits. It can be distinguished as the 70s and 80s ribosomes in prokaryotes and eukaryotes, respectively.

Endoplasmic Reticulum (ER)

• ER is regarded as the cell’s biggest single membrane-bounded compartment.
• It is made up of a network of vesicles, tubules, and cisterns.
• Here Protein synthesis and protein modification take place.
• The membrane of ER is responsible for the synthesis of lipids and proteins for all organelles of the cell
• Depending on how they appear under the microscope, they are divided into the rough and smooth endoplasmic reticulum.

Vacuole

• It is a unique organelle that is used to store extra cell materials.
• It is surrounded by a tonoplast membrane.
• Water can occasionally be found in vacuoles, which gives the cell a turgor pressure that helps it keep its form and survive adverse circumstances.

Functions of an Animal Cell

The fundamental tasks of an animal cell are-

• Reproduction to insure the continuation of the generation 
• Physical growth of the organism.
• Respiration and metabolism fulfill the energy demands of the body.

Animal Cell types

Skin Cells

• These cells are located on the outside of the body and are frequently very thinly layered.
• These cells act as the body’s initial line of defense against germs and various stresses coming from the outside.
• Melanocytes are an example.

Muscle Cells

• These cells have specialized functions that help in the movement of organisms.
• The skeletal, cardiac, and smooth muscles are some examples.

Nerve Cells

• These long, branched cells, also known as neurons, carry electrical impulses throughout the body, aiding in the coordination and control of the entire body.
• Along with neurons, glial and Schwann cells are also present.

Blood Cells

• Red Blood Cells (RBC) and White Blood Cells are the two primary types of Blood cells.
• RBCs utilizing the pigment hemoglobin, function as a transporter of oxygen throughout the body.
• WBCs also referred to as leukocytes, are the body’s defenders that resist and fight infections.

Fat Cells

These large cells, also known as adipocytes, are responsible for storing fat droplets or lipids when the body has an excess of them.

Summary

• Animal cells are made up of various organelles such as Ribosomes, centrosomes, Endoplasmic Reticulum, Nucleus, Nuclear membrane et,c.
• Animal cell types include- skin cells, Muscle cells, Nerve cells, Blood cells, etc.
• Thus, all the cells and their organelles work in unison to bring about proper control and coordination of the entire body.

Frequently Asked Questions

1. Who developed the plasma membrane model?
Ans: Singer and Nicolson presented the fluid mosaic model of the plasma membrane in 1972. According to this, the cell membrane bilayer is made up of phospholipid molecules and proteins are present on the surface and are embedded in the lipid bilayer.

2. What three types of lysosomes?
Ans: The lysosome’s type:

• Primary lysosomes: These are lysosomes that have just formed.
• Secondary lysosomes: When primary lysosomes and phagosomes combine, secondary lysosomes are produced.
• Autophagosomes: They are formed by the digestion of intracellular organelles by the process of autophagy.

3. What are the functions of smooth ER?
Ans: Smooth ER is a membrane-bound organelle that is devoid of ribosomes. The main function of this organelle is the synthesis of carbohydrates, lipids, and steroids. It also performs the metabolism of foreign compounds such as drugs and toxins.

Introduction

A disease is any adverse change from an organism’s usual anatomical, genetic, or physiological state. An illness is accompanied by a distinctive collection of signs and symptoms that are illustrative of that specific condition and aid in its diagnosis and treatment. Diseases can be acquired, congenital, communicable, non-communicable, chronic, and acute diseases. Medical science has cured some of the diseases while some diseases are not curable and hence prove to be fatal. 

Classification of disease

Various diseases can be classified based on the source of detection, causative agents, medium of infection, Duration, Communicability, and Extent.

Based on Communicability there are two types of diseases-

• Communicable disease-These diseases are contagious and are brought on by microbes like bacteria, fungi, viruses, worms, and protozoans. For eg COVID-19, chickenpox, cholera,
• Non- Communicable disease-These are not contagious and do not pass from person to person. These bind the person who contracts them inside. Cataracts, Alzheimer’s, cataracts, and heart conditions are a few examples.

 Based on duration there are two types of diseases-

• Acute diseases-These illnesses are severe, last very briefly, are typically curable with appropriate medical care, and the patient regains their normal bodily functions after being treated. Common colds, fractures, pneumonia, bronchitis, etc. are a few examples. Chronic diseases can develop from acute illnesses if they are not treated on time. 

• Chronic diseases- These illnesses last three years or longer before they are diagnosed. Depending on the organism’s immunity, the disease’s stage of development, the organ or organ system that is affected, and other factors, they may be curable. Such illnesses have the potential of being deadly and incurable. Examples include high blood pressure, diabetes, HIV, arthritis, and cancer etc.

Differentiate between Acute diseases and Chronic diseases

Acute diseases	Chronic diseases
Generally spread from one infected individual to another.	They do not usually spread from one infected individual to another.
These are generally communicable diseases	These diseases are generally non-communicable diseases
These are caused due to contaminated food, water, vectors or from direct or indirect contact with an infected person.	They are caused due to genetic, allergic, deficiencies or environmental factors.
People who are unvaccinated, immunosuppressed or who are constantly travelling to the infected regions have a high risk of getting this disease.	People who show various comorbidities such as high blood pressure, obesity, and various metabolic disorders are at high risk of getting these diseases.
Poor living conditions, underdeveloped healthcare systems and lack of cleanliness are responsible for these kinds of diseases.	Behavioural factors, Poor dietary habits and Genetic factors are responsible for these kinds of diseases.
Eg- COVID-19, SARS, Chlorella, TB etc	Eg- Cancer, HIV, Diabetes etc

Diseases due to environmental changes

Polluted environment is one of the main factors for diseases to occur. Some of these are explained below.

• Air pollution: Respiratory disorders such as chronic bronchitis, emphysema, lung cancer, acute lower respiratory infections, etc. are caused by harmful gases in the air such as sulphates, nitrates, together with VOC, PM and Polyaromatic Hydrocarbons (PAHs).
• Water pollution: Several pathogenic bacteria can cause cases of botulism, dysentery, cholera, giardiasis, amoebiasis, naegleriasis, etc. These are caused due to contaminated water as  sewage sources, swimming pools, or untreated drinking water containing all different kinds of microbes.
• Toxins- The presence of lead, arsenic, and mercury in the environment are some  toxins, and they cause various diseases including malignancies like mesothelioma and melanoma, cardiovascular diseases like atherosclerosis, kidney ailments, and cerebrovascular diseases.

Summary

Disease is a state of the body that deviates from its usual state. There are many different ways to categorise diseases, including according to how long they have persisted, what caused them, how they spread, and how contagious they are.Acute disorders manifest abruptly and last only briefly. Chronic diseases are those that take longer to develop, last for a year or, occasionally for a lifetime. A healthy person can contract a communicable disease from an infected person using a variety of carriers, such as air, water, and animals. Cardiovascular diseases, CRDs, cancer, and diabetes are examples of non-communicable diseases that cannot be passed from one person to another. Pollution in the environment can also cause diseases.

Frequently Asked Questions

1. What do zoonotic illnesses mean?
Ans: Diseases which are caused by animals.i.e. animals carry disease-causing microbes such as bacteria or viruses are known as zoonotic illness. These diseases can be spread by scratches, body fluids etc. Eg- malaria, rabies, zika virus etc.

2. Explain the terms- Pathogen, Pathogenesis.
Ans: Pathogen- Any organism which causes disease is known as a pathogen eg- virus, fungus, bacteria etc.

Pathogenesis- It is a series of events which occur between the entry of the pathogen inside the body  and spread of the disease in the body.

3. How can the  transmission of communicable illness be prevented?
Ans: It is crucial to improve one’s personal hygiene as well as societal awareness and societal hygiene. Vaccinations have already contributed to the global eradication of several serious diseases.

Introduction

A dam is a man-made obstruction built across a river or underground stream to restrict the flow of water. This results in the creation of artificial lakes or reservoirs. Then, this has other uses. such as irrigation, domestic purposes, flood control, commercial purposes, aquaculture, electricity production, etc. They used bricks, clay, concrete, cement, iron riding, etc. to build their construction. Even though it provides a lot of benefits, there are some drawbacks as well. The environment of the river will be impacted when more dams are built over it. due to the abundance of aquatic life in the river. There is therefore a pressing need for a dam alternative.

Advantages of Dams

A dam has several advantages, ranging from economic to social advantages. The following is a list of benefit of a dam.

• Water storage: It can serve as a sizable water reserve that can be used for domestic, commercial, and agricultural purposes. Additionally, it has the capacity to accept extra surface water.
• Recreation: Dam’s are a point of public attraction as many leisure activities like boating, camping, swimming, etc. can be done in this area.
• Irrigation:The dam is a significant source of water for irrigation.
• Debris control: The dam has improved environmental protection by reducing the amount of trash thrown into rivers.
• Electricity production: Hydropower is a crucial source of electricity because it doesn’t produce any chemical waste. The majority of the nation’s primary source of electricity is generated from water.

Disadvantages of Dams

Dams are constructed to generate additional electricity for use by people. However, the bulk of these dams are unable to make a significant impact on the generation of power for human needs. Instead, it has certain negative repercussions on both the ecology and people as a whole. Some of them are mentioned below-

• Dam construction has an negative impact on the aquatic life that exists in the water.
• There is lots of water wastage during the process of dam construction.
• It has affected the people who live nearby as a sizable portion of land has been buried to serve as a water reservoir.
• Due to dam construction biodiversity in the water has reduced.
• There is an increased sediment accumulation
• Soil erosion has occurred in places nearby to the dams.
• There is a danger of catastrophe because by chance if the dam structure breaks it will threaten the lives of  thousands of people,
• Overflow of water in the dam may happen if more water reaches the surface by rain which might lead to flooding in the nearby areas.

Alternative solutions to Dams

Dams have a number of drawbacks since they are not the ideal solution for meeting human requirements. Therefore, finding a dam replacement is essential. Some of the alternative solutions to dams are given below-

• Concentrating on alternative energy sources-The construction of dams is a result of the rise in electricity demand; therefore, finding an effective source of energy production will lessen the danger posed by dams. Some common alternative energy sources ares nuclear power plants, thermal power plants, solar electricity, wind power, etc.
• Reuse of water: The dam provides water for numerous uses that. Therefore, locating new alternate water sources can also help to lower the number of dams. For instance, sewage water can be recycled and used again for a variety of various purposes, including industrial and agricultural ones.
• Managing flood: By reducing the water runoff we can control the flood of many rivers. Since dams play a prominent role in the prevention of floods in rivers.
• Concentrate more on the current dams: Only small a fraction of dams are used effectively. Hence,prior to building a new dam, one must pay attention to the older dams and make the best use of them.As a result, fewer dams may be constructed to bridge rivers.
• Groundwater recharge: Increased water deposition from surface water to groundwater is known as groundwater recharge. This process increases the water content below the ground level which can be used for various other purposes.

Summary

Water is a priceless resource that is essential to maintaining human life. It may be used for everything from generating electricity to drinking puropses. Consequently, a reliable water source is always going to be required. A dam is a man-made structure designed to preseve water. Nevertheless, while there are numerous benefits of dams, there are also some drawbacks. Being a man-made construction, it has a severe impact on the ecosystem around us. Therefore, a water  resource other than the dam is desperately needed. Alternative methods of dams include replenishing the groundwater table, locating alternate energy sources, etc. If appropriate measures are not taken into consideration, we could face a number of issues. And hence for this purpose new technologies must be implemented..

Frequently Asked Questions

1. Which of the dams on Earth is the oldest?
Ans: The dam Jawa, which is situated in Jordan, is the oldest dam still in use today. There are still some of this dam’s remains.

2. How long do dams last?
Ans: A dam’s lifespan is estimated to be 50 years on average. In this lifespan, it can function successfully. There are also other dams that date back far more.

3. Can a dam contaminate water?
Ans: Since dams stop the flow of water, they can accelerate the growth of any existing microbes in the water, which can render the water hazardous. The number of diseases spurred on by water pollution has been rising daily. Additionally, metallic components can also accumulate in such stagnant waters which can further harms marine life.

Introduction

In India notably, agriculture has been practised for thousands of years without the use of artificial tools. Fertilizers that were developed in the middle of the 19th century were powerful, affordable, and easily accessible at the time, but they also had several negative side effects, such as soil erosion, water pollution, and animal body accumulation. To combat these side effects, efforts were made to find cures while simultaneously maintaining a high yield. In the 1930s, Albert Howard introduced an organic farming system to Britain by fusing his scientific techniques with traditional farming practices from India (manure, compost, and crop rotation).

What is Agriculture?

Agriculture derives from the Latin words “ager,” meaning “field,” and “colo,” meaning “to cultivate,” meaning to use or prepare a field or piece of land for producing crops. It also covers raising animals like cattle for dairy needs.

What is Organic Agriculture? 

Organic farming is the practice of cultivating crops using organic farming techniques. Compost, manure, and green manure are examples of natural fertilizers used to boost fertility and plant growth. Crop rotation is one natural or biological technique suggested to improve soil fertility. The land is allowed some time to rest after raising a crop so that it can naturally regain its fertility.

Types of Organic Agriculture

Organic agriculture is categorized into two types.

Pure organic farming:

• In this kind of organic farming, farmers only utilize natural ingredients to promote plant growth, improve soil fertility, and stop soil erosion. 
• It is best to avoid using any kind of pesticide because it hurt crops, important soil bacteria, and even people who eat the food.

Integrated organic farming:

• This method of organic farming, also known as the “Zero waste” technique, is carried out in such a way that residues or wastes are produced in “zero” proportions.

Aims of Organic Agriculture

• Protecting the environment
• Natural resource conservation
• Keeping the ecological balance 
• Improvement of soil fertility 
• Stop soil erosion 
• Protecting wildlife and plants from the negative effects of artificial fertilizers and chemicals 
• Maximizing agricultural production
• Reduce the number of chemicals we use to produce food

Practices Followed During Organic Agriculture:

• Crop rotation: To preserve soil fertility, different crops are cultivated in alternate years on the same plot of land. 
• Green manure and cover crops: Green manure improves soil fertility and is good for crop plant growth. The term “cover crops” refers to plants whose primary purpose is to prevent soil erosion, but which also progressively mix with the soil as they naturally deteriorate and serve as green manure.
• Compost and manure are made consisting of organic materials that provide nutrients for plants, such as cow dung and other crop plant wastes.
• Bio pest control: By feeding on disease-causing pests, beneficial organisms found in soil can suppress harmful pests.

Steps Involved in Developing Organic Farms

• Using organic management techniques rather than merely conventional farming methods. 
• Environmental conservation and wise use of natural resources. 
• Only natural or biological approaches, such as crop rotation, manure, compost, and cover crops, are employed instead of synthetic media that use chemicals. 
• Weeds should be pulled out since they compete with crops for nutrition and grow alongside them. 
• Pest management by biotechnology for crops. the method of organic farming that is integrated.

Disease Management

• Because infections are a major factor in plants’ decreased output, disease management is necessary. This is accomplished by keeping beneficial organisms in the soil that feed on destructive pests that degrade plants. 
• The major advantage of organic farming is that it preserves beneficial bacteria and fungi that would otherwise be eliminated by the use of conventional fertilizers and pesticides through a system of “checks and balances.” 
• These microbes aid in preserving the soil’s ecosystem and inhibit the development of pathogenic bacteria and fungi.

Methods of Organic Agriculture: 

• Weed management: Organic farming attempts to lessen the presence of weeds rather than eradicate it.
• Biological pest control: Beneficial microbes that are retained and not permanently destroyed keep harmful disease-causing microbes in check.
• Soil Management: As the most crucial factor in plant growth, soil management involves a variety of techniques. Cover crops, manure, compost, and the maintenance of beneficial organisms are among the measures used to increase its fertility.
• Polyculture: To quickly meet the need for food, many different types of crops are grown at the same time.
• Manure and compost: To increase output while causing the least amount of damage to the soil and plants, organic materials such as plant and animal waste are utilized to create natural fertilizers.

What are the Benefits of Organic Agriculture? 

• Environmental protection is facilitated by reducing chemical use and the pollution that results from it. 
• Since no toxic pesticides are applied, it protects non-target creatures, including people and animals, whose health is impacted when these chemicals build up in their systems. 
• Because organic farming uses naturally produced manure, the high cost of pesticides is reduced. 
• It helps to lessen erosion while also enhancing the soil’s physical attributes including fertility and water-holding capacity.
• Additionally, crop failure risk is decreased.

Disadvantages of Organic Agriculture

• It’s hard to find organic manure in large quantities. 
• Even though ordinary Indian farmers’ agricultural methods are organic, they are not recognized as such and are nonetheless sold for the same prices as conventional (normal) farming produce. 
• A regular farmer cannot understand the regulations of organic farming, which include production, processing, transportation, and crucial certification. 
• Farmers don’t like certification since it is an expensive process that necessitates a lot of paperwork. 
• Since organic farming uses special techniques, its products are typically more expensive for customers.

Frequently Asked Questions

1. Is organic farming a new or traditional practice in India??
Ans. Since the beginning, only natural methods have been utilized in India. Artificial methods only began to be used in the 19th century, but as soon as people realized the problems they brought, they quickly returned to favouring organic farming, not just in India but also in other foreign nations.

2. How is organic farming doing in India?
Ans. In India, there is a beginning of organic farming; just 2% of the land is used for organic farming; the remainder is used for conventional farming using synthetic chemicals. By 2030, this will be more successful.

3. What are the main advantages of organic farming over conventional agriculture?
Ans. Preventing soil erosion has several positive effects, including higher soil fertility, better growth conditions, and reduced water contamination. This is a significant issue with conventional farming.

4. What benefits do conventional farming techniques have over organic ones?
Ans. Advantages of Conventional farming: The plants created all have the same genetic makeup. Using this technique, plenty of plants can be grown swiftly. While some plants generate few or no seeds, others do not allow their seeds to germinate.

Introduction

Food security is currently a big issue due to the growing global population. As a result, fertilizer has become crucial to agriculture to feed the world’s expanding population. Fertilizers are substances that aid in providing nutrients to the soil, enhancing crop yield. Additionally, it aids in preserving and enhancing soil fertility. Inorganic, organic, and biofertilizers all work in somewhat different ways to release nutrients into the soil and each has advantages and disadvantages in terms of crop growth and soil fertility.

What are Fertilizers?

Fertilizers are nutrient-rich compounds that are put into the soil to boost soil fertility, which, if added to the needed amount of soil, results in better and higher yields.  Urea hydrolysis is a basic illustration of how fertilizer is applied into the soil.

\[{\bf{CO}}{({\bf{N}}{{\bf{H}}_2})_2}\; + \;{\rm{ }}\;{{\bf{H}}_2}{\bf{O}}\;{\rm{ }}\; + \;{\rm{ }}{\bf{Urease}}\;\;{\bf{2N}}{{\bf{H}}_3}\; + \;{\bf{C}}{{\bf{O}}_2}\]

Here, the most popular fertilizer, urea, or \(CO{\left( {N{H_2}} \right)_2}\), reacts with urease, a naturally occurring chemical produced by the soil, when it is applied to moist soil. It causes the synthesis of \({\bf{N}}{{\bf{H}}_3}\;{\bf{and}}{\rm{ }}{\bf{C}}{{\bf{O}}_2}\), both of which promote soil fertility and plant development. The three essential macronutrients that plants require in the greatest amounts are Nitrogen (N), Phosphorus (P), and Potash (K). Sulphur (S), Calcium (Ca), and Magnesium (Mg) are additional macronutrients that plants also require, but in smaller amounts.

Types of Fertilizers

Fertilizer is categorized into the following groups according to the composite makeup and various techniques of releasing nutrients:

• Inorganic fertilizers: Inorganic fertilizers are mostly made of chemical compounds like urea, ammonium nitrate, potassium chloride, etc. These fertilizers can’t decompose naturally. These fertilizers are often known as synthetic or artificial fertilizers. It is subdivided into two categories:
  • Macronutrients Fertilizers: Primary macronutrients that are rich in Nitrogen,Phosphorous, and Potassium are crucial for any plant’s rapid and healthy growth. Secondary macronutrients, which are similarly important to plants and contain calcium, sulfur, and magnesium, constitute another category.
  • Micronutrients Fertilizers: These fertilizers are designed to give trace amounts of nutrients like Copper, Zinc, Boron, Iron, and Chlorine, among others, even though they have a limited purpose in meeting the basic demands of plants.
• Organic Fertilizers: These easily biodegradable fertilizers are made from naturally occurring materials like sewage, guano, slurry, manure, worm castings, etc. Then, a vast number of microorganisms work to break down these naturally occurring substances into smaller and soluble particles.

• Bio-Fertilizers: Biofertilizers are compounds that generate nutrients from microorganisms that solubilize nitrogen and phosphate. Examples include Pseudomonas, Azotobacter, etc. These microorganisms or bacteria improve the soil’s nutritional content.

Application of fertilizers

• It aids in increasing crop yield and replenishing the soil’s depleted nutrients.
• The ability of nitrogen in fertilizers to make soils acidic is lessened. 
• To grow healthy crops, nitrogen-based fertilizers should be applied as much as possible. 
• Chemical fertilizers can be used in smaller amounts while yet providing the soil with enough nutrients to produce a larger yield. 
• Where two crops are growing, using biofertilizers greatly aids in preventing the production of undesirable crops. They are used to cultivate a variety of crops.

Benefits of Fertilizers

Inorganic fertilizers (Chemical Fertilizers)	Organic Fertilizers	Biofertilizers
It is simpler to use and handle.	Helpful in bringing soil nutrients to the surface and ensuring that they are delivered to plants in an even distribution.	It guarantees soil enrichment.
It easily dissolves in soil and has an immediate impact on crops since they contain soluble salts.	Keeping the moisture constant, it helps to relieve soil stress.	These fertilizers contain microorganisms that break down complicated organic compounds into simpler, nutrient-rich forms that plants may easily access.
These fertilizers are extremely productive, even if they are only used in modest quantities.	It is environmentally friendly.	Through processes like nitrogen fixation and phosphorus solubilization, it naturally raises the nitrogen and phosphorus content in the soil, making it more nutrient-rich.
By allowing water to penetrate the soil, fertilizers like gypsum help crops develop healthily.	On plants, it has a less harmful effect.	These fertilizers provide hormones like amino acids, vitamins, etc. that promote plant root growth.
Utilizing fertilizers like lime, which lessen the impact of acid on the soil, aids in preserving the soil’s pH equilibrium.	These fertilizers are a rich source of soil bacteria, which in turn aid in growing a healthy crop and ward against pest attacks.

List of Chemical Fertilizers

Nitrogenous Fertilizers	Phosphatic Fertilizers	Potassic Fertilizers
UreaAmmonium sulphate    Ammonium nitrateSodium citrate Potassium nitrateCalcium ammonium nitrate	Rock phosphatePhosphoric acidSuper phosphatesDiammonium phosphate	Muriate of potashSulphate of potash Potassium metaphosphate Potassium nitrate

Summary

Fertilizers are nutrient-rich compounds that are put into the soil to boost soil fertility, which, if added to the needed amount of soil, results in better and higher yields. Fertilizer is categorized into the following groups according to the composite makeup and various techniques of releasing nutrients: chemical, organic, and biofertilizers. To grow healthy crops, nitrogen-based fertilizers should be applied as much as possible. 

Frequently Asked Questions

1. How crucial is fertilizer to feeding the world’s population?
Ans. Fertilizers have nutrient-rich components, and adding them to the soil makes the soil more fertile, which helps to enhance crop output. The rapidly rising agricultural yield aids in supplying the expanding population’s growing need for food.

2. Does incorporating organic fertilizer into the soil enhance crop quality and soil health?
Ans. Organic fertilizers are made from things like slurry, dung, seaweed, etc. Microorganisms transform these complicated compounds into simpler compounds. These more straightforward or nutrient-rich substances are readily absorbed in the soil, which aids in enhancing soil quality and raising crop yields.

3. Can fertilizers harm a person’s health?
Ans. Chemical fertilizers are among those that can have an impact on human health because they include heavy metals like lead, mercury, and others that can harm a person’s kidneys, liver, and lungs.

4. What kind of fertilizer is most used in agriculture, and why?
Ans. To feed a large population, food production must increase. Only fertilizers made of chemicals or inorganic materials could make this possible. The majority of chemical fertilizers are used to produce the highest yield. Given that it contains macronutrients and micronutrients, it provides the soil with a sufficient amount of nutrients to boost crop yield.

5. Why do plants burn when fertilizers are used excessively?
Ans. Salt-based nutrients are present in fertilizers. These salts readily dissolve in water; however, salts used in excess leave the water undissolved. Plants are unable to absorb water and other nutrients because of the undissolved salt that stays in the soil. As a result, it greatly disturbs the soil’s structure and causes plants to burn.

Introduction

All of the body’s cells require energy to support various metabolic processes, thus every living thing engages in cellular respiration to release energy, which is then stored in the form of ATP. After ingestion, food is transported into the stomach via the oesophagus, where stomach acids and enzymes break it down into several smaller bits, including glucose. Since glucose is the most prevalent monosaccharide and the first substrate for the metabolism of carbohydrates, where it is broken down to release energy, glucose and ATP are the molecules that carry the energy.

Definition of Cellular Respiration

All plant and animal cells produce energy through a process called cellular respiration (excluding RBCs). Food glucose is broken down into carbon dioxide, water, and energy with or without oxygen throughout this process. As a result, it liberates ATP and releases carbon dioxide as a waste product (adenosine triphosphate).

Difference between Respiration and Breathing

Respiration	Breathing
Respiration is the physiological process of breathing in and breathing out. Energy is released from cells during the chemical breakdown of food-derived glucose.	Breathing is the movement of oxygen into the body from the outside environment and the release of carbon dioxide from the lungs into the outside environment.
It is categorised into cellular respiration and physiological respiration.	Since breathing is a form of respiration, it is often referred to as physiological respiration.
In cells, and notably in cellular organelles like the cytosol and mitochondria, cellular respiration takes place.	It takes place in the lungs.
There is the involvement of enzymes.	There is no involvement of enzymes.
It produces ATP that is converted into energy.	It does not produce energy.

Glycolysis

• One glucose molecule is broken down into two pyruvate molecules in this process, which also results in the creation of ATP. 
• Every cell in the body contains it in the cytoplasm. Hexokinase enzyme converts glucose to glucose-6-phosphate.
• By using phospho-hexose isomerase, which are isomers of one another, glucose 6-phosphate is converted to fructose 6-phosphate. 
• By phosphorylating fructose 6-phosphate, phosphofructokinase catalyzes the irreversible conversion of fructose 6-phosphate to fructose 1,6-bisphosphate.
• Aldolase catalyzes the breakdown of fructose 1,6 bisphosphate into glyceraldehyde 3-phosphate and dihydroxyacetone phosphate.
• The reversible interconversion of glyceraldehyde 3-phosphate and dihydroxyacetone phosphate is carried out by phosphotriose isomerase.
• Glyceraldehyde 3-phosphate is converted to 1,3-bisphosphoglycerate by glyceraldehyde 3-phosphate dehydrogenase. 
• In this stage, \(NA{D^ + }\) is converted to \(NAD{H^ + }\) and \({H^ + }\), which adds a phosphate group to glyceraldehyde 3-phosphate. With the creation of ATP, the enzyme phosphoglycerate kinase converts 1,3-bisphosphoglycerate into 3-phosphoglycerate.
• Phosphoglycerate mutase converts 3-phosphoglycerate into 2-phosphoglycerate, and these two substances are isomers. 
• Enolase transforms 2-phosphoglycerate into the highly energetic molecule phosphoenolpyruvate once water is removed. 
• In the presence of pyruvate kinase, phosphoenol pyruvate is transformed into pyruvate along with the creation of ATP.       
•  

Generation of ATP: Two pyruvates, two NADH, and two ATP molecules are the final products of glycolysis. Due to the conversion of glucose into two pyruvates, 8 ATP molecules are produced.

Krebs Cycle

Acetyl CoA is converted into carbon dioxide and water by some chemical processes called Krebs cycle.

• Pyruvate is converted to acetyl CoA through oxidative decarboxylation by pyruvate dehydrogenase. 
• The elimination of carboxylate groups to create carbon dioxide is known as oxidative decarboxylation. Acetyl CoA and oxaloacetate are condensed by citrate synthase. 
• Aconitase converts citrate into isocitrate.
• Isocitrate dehydrogenase uses oxidative decarboxylation to change the isocitrate to oxalosuccinate, which is then transformed into -ketoglutarate. 
• By removing the carboxylate group from ketoglutarate and generating carbon dioxide, the enzyme ketoglutarate dehydrogenase transforms ketoglutarate to succinyl CoA. 
• Succinate thiokinase causes succinyl CoA to be converted to succinate. A phosphorylated group is added to GDP to create GTP, which is then converted into ATP by a protein called nucleoside diphosphate kinase. 
• By catalysing the conversion of succinate to fumarate and producing \(FAD{H_2}\), succinate dehydrogenase.
• By including water, fumarase catalyses the conversion of fumarate to malate.
• Malate dehydrogenase converts malate to oxaloacetate and generates NADH in the process. 
• The cycle is maintained by mixing the oxaloacetate with more acetyl CoA molecules.
• 

Generation of ATP: In the Krebs cycle, 12 ATP is produced as a result of the production of 2 \(C{O_2}\), 3 NADH, and 1\(FAD{H_2}\).

Electron Transport Chain or Terminal Oxidation or Oxidative Phosphorylation

The proton gradient created by the electron transport chain (ETC), a chain of proteins that transports electrons through the mitochondrial membrane, powers ATP generation. A series of ETC enzyme complexes: 

• NADH-ubiquinone reductase – Complex I
• Succinate CoQ reductase – Complex II
• Ubiquinone-cytochrome c oxidoreductase – Complex III
• Cytochrome oxidase – Complex IV 
• ATP synthase – Complex V 

Through electron carriers such as flavoproteins, cytochromes, coenzyme Q, nicotinamide nucleotides, and iron-sulfur proteins, these catalyze the transport of electrons.

Since energy is lost during the passage of electrons through ETC, the ATP synthase complex uses the energy to produce ATP from ADP, a procedure known as oxidative phosphorylation. 32 ATP molecules are generated during oxidative phosphorylation and ETC.

Differences between Glycolysis and Krebs Cycle

Glycolysis	Krebs cycle
It involves both aerobic and anaerobic respiration.	It involves only aerobic respiration.
The substrate substance is glucose.	The substrate material is acetylAcetyl CoA.
Glycolysis takes place in the cytoplasm.	The KrebsKrebs cycle takes place in the mitochondria.
It consumes two molecules of ATP.	It does not consume ATP.
Carbon dioxide is released in glycolysis.	Carbon dioxide is not released in the Krebs cycle.
It is a linear enzymatic reaction.	It is a non-linear pathway.
It occurs in both eukaryotes and prokaryotes.	It occurs in eukaryotes.

Difference between Aerobic and Anaerobic Respiration

Summary 

All plant and animal cells produce energy through a process called cellular respiration. Due to the conversion of glucose into two pyruvates, 8 ATP molecules are produced in glycolysis. In the Krebs cycle, 12 ATP is produced as a result of the production of 2 \(C{O_2}\), 3 NADH, and 1 \(FAD{H_2}\). 32 ATP molecules are generated during oxidative phosphorylation and ETC.

Frequently Asked Questions

1.How do electron carriers function?,
Ans. The metabolite is present at one end and oxygen is at the other end, therefore the electrons are carried by a series of proteins.

2. What are the processes in the conversion of glucose to pyruvate that require energy?
Ans. By using enzymes in intermediary processes, glyceraldehyde 3-phosphate and dihydroxyacetone phosphate are produced from glucose. These processes call for energy.

3. What is oxidative phosphorylation?
Ans. Oxidative phosphorylation, which takes place in the mitochondria, is the addition of the phosphate group through reactions that use the energy produced when ATP is made from ADP.

4. What is the importance of cellular respiration in living organisms?
Ans. Energy is released during cellular respiration, which activates a number of bodily processes. Therefore, ensuring the survival of living things is important.

Introduction

The air is a fundamental element of planet Earth that sustains life. The broad term “air” is used to describe the mixture of gases that makes up the earth’s atmosphere. It is a clear gas required for breathing and performing regular cellular activities. Air is a very essential and makes up the atmosphere of the earth.

It has the following other applications-

• All life depends on air to thrive, including humans, plants, animals, and other species.
• The air is necessary for the water cycle to take place.
• It facilitates combustion and breathing.
• It keeps the temperature constant.
• Air assists in the process of pollination in wind-pollinated plants.

Components of Air

The air around is composed of various components given below-

• Oxygen makes up around 21% of the air.
• The highest amount of gas present in the air is Nitrogen, which makes up 78% of the total air.
• Argon is 0.9% of the total air.
• Carbon dioxide is the lowest around 0.04% of the air.
• There are still other gases which are present in very lower concentrations eg. water vapour.
• Microscopic airborne particles known as “aerosols”  are also present in the air and are present in minute quantities.
• These aerosols include bacteria, suspended dust, pollen, and spores.

Properties of Air

• Air is colourless and odourless and cannot be seen, heard or touched.
• It is a mixture of many gases and they occupy space and matter.
• Air exerts pressure. Near the surface, the air pressure is more and at higher altitudes the air pressure is low.
• When heated the air expands and when cooled the air compresses.

Uses of Air

Respiration

• Respiration is the process where gaseous exchange occurs and oxygen is inhaled and carbon dioxide is exhaled.
• The two main gases involved in respiration are carbon dioxide and oxygen.
• Plants and animals require oxygen to convert the chemical energy found in food into energy that can be used for various metabolic processes.
• This energy is used in all actions of growth, development, locomotion and reproduction.
• Oxygen is created through the process of photosynthesis, which occurs when plants use carbon dioxide to make chemical energy while utilizing light energy.
  

Combustion

• A fuel oxidises when it is burned and produces lots of energy.
• This is an exothermic reaction wherein light and heat are generated.
• Any carbon-containing substance that is burned in the presence of oxygen produces carbon dioxide, water vapour, heat, and light energy.
• Colourful flames are created when methane, an essential element of combustion, combines with air. These colourful flames are an indicator of the combustion reaction.
• Explosive burning might occur if there is too much oxygen present hence to prevent this nitrogen gas is present in the atmosphere.
• Nitrogen does not contribute to combustion and inhibits too much oxygen from causing higher reactivity. Therefore, these two components work together to make sure that fuel energy is used in a controlled way.
• The heat that is generated during the process of combustion is used to cook, run our vehicles, generate electricity etc.

Regulation of temperature

• The earth’s surface is kept at a constant temperature by air.
• The density of hot air is less and hence it rises above the ground. This leads to the formation of a low-pressure area which is quickly filled by cool air.
• This phenomenon leads to the formation of winds.
• As the temperature of the air rises the air moves up draws in cooler air from the surroundings, warms it up, and the cycle repeats.
• When hot air rises, it radiates heat into space before sinking back to earth.
• Convection is the process of moving heat, and this is referred to as temperature regulation.
• Heat is transferred in this way from hotter to colder places and thus the temperature of the earth is regulated.
• The atmosphere and air also help to cool the earth and protect it from the sun’s excessive UV rays.

Summary

Air surrounding the earth makes up its atmosphere. The air is a mixture of gases and is essential to many living things. Air consists of 78% of nitrogen, 21% oxygen, 0.9% argon, and 0.04% carbon dioxide, and there are traces of other gases as well. The thick layer of air supports vital life-supporting activities. Contrarily, air is a substance and it has mass, can be compressed, and takes up space. Air performs the following major processes—breathing, combustion, and regulating the earth’s temperature.

Frequently Asked Question

1. Give the function of the ozone layer
Ans: The ozone layer, which is found in the stratosphere of the earth and absorbs the majority of the sun’s ultraviolet rays, works as a screen to protect the planet from these rays.

2. What does acid rain mean?
Ans: Polluted air consists of oxides of nitrates and sulphates. These oxides react with water vapour and other air components to form sulfuric acid and nitric acid. When there is rainfall both of these acids fall on earth which is termed acid rain. This acid rain is not only harmful to people but also affects various other living organisms.

3. What are the ill effects of air pollution?
Ans: Air pollution is a very severe problem that aggravates pre-existing respiratory and cardiac problems and causes several pollution-related ailments. Common diseases caused due by air pollution are lung cancer, stroke, chronic obstructive pulmonary disease (COPD), and respiratory infections.

Introduction

In the farming and agricultural sectors, the tools used to streamline the process are referred to as agricultural implements. To create a productive and helpful environment, agricultural operations today require a different range of tools, such as drills, diggers, furrows, sickles, and so on. Without the use of the implements that are supposed to finish these processes, the current situation in agriculture demonstrates development. In this tutorial, we’ll discuss agricultural equipment and how they affect the farming and agricultural industries.

What is Agriculture?

Agriculture is the activity of growing crops and rearing animals that supports human sedentary behavior and the growth of sustenance. It may be involved in the production, processing, and distribution of agricultural products. For most rural communities, it serves as their primary source of income. In metropolitan regions, individuals are provided with vegetables and grains for food.

Significance of Agriculture

• The majority of the world’s food supply comes from agriculture, which also guarantees the population’s access to food and nourishment. 
• Since agriculture contributes over 20% of GDP (Gross Domestic Product), it is regarded as the main source of income for the nation. 
• A large number of people have employment opportunities in agriculture. 
• It plays a significant part in the export of significant goods on a global scale and in balancing a nation’s crucial expenditures while preserving its foreign currency. 
• Additionally, it generates fibers, raw materials, and biofuels.
• Utilizing the production and selling of agricultural goods eliminates poverty in rural regions. 
• Selling the by-products of raising animals brings considerable profit for farmers.

What are Agricultural Implements?

Agriculture implements and farming equipment are tools or pieces of machinery used to complete tasks quickly. These are used in agriculture to lessen physical labor and increase crop output. Early farmers developed their own labor and time-intensive tools, which were difficult to use. After modernization, cutting-edge processes and tools have taken the place of outdated ones.

To make work easier, a variety of agricultural implements are used in agriculture. The following is a list of important agricultural tools: 

• Planting tools 
• Harvesting equipment
• Irrigation equipment
• Tools for cultivating soil

Types of Agricultural Implements

Farmers employ a variety of agricultural instruments to increase crop yield. It includes the following:

Soil cultivation implements

• The cultivation of the soil is a crucial stage because it enables crop roots to enter the soil and absorb nutrients and water. 
• Soil preparation is done with basic equipment like a hoe, a plow, and cultivators. 
• The land is plowed and made ready for cultivation with the use of spike, drag, and disc harrows.

Irrigation machines

It is made up of a pump that draws water from the bottom and a pivot irrigation system that supplies the crops with the right amount of water.

Planting machines

• The plant is protected from animals and birds attack by the use of a seed drill, which provides a deep and proper area for planting. 
• It enables the plants to receive enough sunlight, nutrients, and water. 
• After crop cultivation, a large area is seeded using tools including air seeders, broadcast seeders, transplanting implements, and more.

Harvesting implements

• Cutting fully developed and ripe crops is the procedure of harvesting. 
• Crops are harvested using harvesting equipment like pickers, trailers, and diggers.

Division of Crops

The agricultural process develops food grains for human consumption and utilizes their raw materials for industrial use. Crops are cultivated according to the type of soil and weather conditions. There are three major divisions of crops. 

Kharif crop

• In the monsoon season, the seedlings of crops begin to grow and are harvested in the autumn.
• A warm climate and excess water are necessary for its growth.

Rabi crop

• In humid conditions, seeds germinate and develop well, and crops grow well. 

Zaid crop

• During the period between Kharif and Rabi, the Zaid crop develops.
• For blooming flowers, warm, dry weather is required for crop growth.

Type of crop	Season	Examples
Kharif crop	September to October	Millets. maize, rice, soybean, cotton
Rabi crop	October to December and April to May	Barley, oats, mustard, wheat, peas
Zaid crop	March to June	Watermelon, cucumber, muskmelon, pumpkin, pulses

Categories of Crops

Depending on their use, crops can be classified into two types.

• Food crops: Food crops are mainly grown for human and animal consumption. There are several major food crops, such as vegetables, oilseeds such as sunflower, groundnut, sesame, and cereals like paddy, wheat, and fruits.
• Cash crops: Crops that are grown to generate income rather than for domestic consumption are called cash crops. Rubber, tea, coffee, jute, spices like mustard, chili, turmeric, garlic, coriander, and some medicinal crops are some of the most important cash crops.

Summary

Agriculture implements and farming equipment are tools or pieces of machinery used to complete tasks quickly. Farmers employ a variety of agricultural instruments to increase crop yield.  The agricultural process develops food grains for human consumption and utilizes their raw materials for industrial use. Depending on their use, crops can be classified into two types such as food crops and cash crops.

Frequently Asked Questions

1. How does agriculture have such a big impact on a nation?
Ans. A nation’s economy is based on agriculture because it provides food, is a source of commercial products, creates employment, and eliminates poverty. More than half of the population solely depends on agriculture for a living.

2. Why are outdated agricultural equipment and practises replaced?
Ans. In addition to hand-made tools, traditional techniques are tedious and time-consuming. Therefore, advanced techniques and equipment are used to increase crop production quickly. 

3. What farming tools are used to get the soil ready for cultivation?
Ans. Disc harrows, drags, and hoes are agricultural implements used to plow the soil, allowing roots to penetrate the ground and absorb moisture and nutrients more easily.

4. What kinds of crops are grown during the monsoon and summer seasons?
Ans. Kharif crops are produced in the monsoon season of September and October. Zaid crops are produced in the summer season, from March to June. Rabi crops are also produced in the summer, from April to May.

5. What are the main tools used in agriculture?
Ans. Machines for planting, harvesting, irrigating, and cultivating the soil are the most important agricultural implements. The use of these is widespread in organic farming and commercial agriculture.

Introduction

All living things require energy to carry out their many tasks, such as breathing, growth, metabolism, and movement. Because of this, cells need a constant flow of energy to support their development, maintenance, and repair. Although the sun is a good source of energy, not all types of life can use it directly. The process by which all the cells in living things produce energy is called cellular respiration. The body receives energy via the breakdown of glucose, whether oxygen is present or not.

What is Aerobic Respiration?

During aerobic respiration, glucose present in the food is converted into water and \(C{O_2}\). It releases energy in the form of ATP (Adenosine triphosphate) and each ATP hydrolysis gives 7.3 kcal/mol. Through this catabolic process, food is converted into energy that is needed for various body functions. Eukaryotes, prokaryotes, and plants undergo this process. The process is also known as oxidative metabolism.

Aerobic Respiration Equation 

When glucose is completely burned, carbon dioxide and water are released with energy as a byproduct. The overall equation of aerobic respiration is given here,

\[{{\bf{C}}_6}{{\bf{H}}_{12}}{{\bf{O}}_6}\left( {{\bf{Glucose}}} \right) + {\bf{6}}{{\bf{O}}_2}({\bf{Oxygen}}){\bf{6C}}{{\bf{O}}_2}\left( {{\bf{Carbon}}{\rm{ }}{\bf{dioxide}}} \right) + {\bf{6}}{{\bf{H}}_2}{\bf{O}}\left( {{\bf{Water}}} \right) + {\bf{Energy}}\]

About 2900 kJ are released and transformed into ATP, which is used for several purposes.

Steps Involved in Aerobic Respiration

The process of aerobic respiration involves four major steps with intermediate reactions. Those are as follows.

Glycolysis

Initially, glycolysis was derived from the Greek words glyco (meaning sugar or sweet) and lysis (meaning dissolution). As a universal sequential reaction, it occurs in both aerobic and anaerobic respiration in the cytosol of a cell.

• Two ATP molecules and two NADH molecules are produced when one glucose (glycogen) molecule breaks down into two molecules of three carbon compounds pyruvates.
• NADH (NAD+H) is the reduced form of NAD (nicotinamide adenine dinucleotide), which is the electron acceptor. The further process of aerobic respiration is carried out by these molecules. 
• Glycolysis is also called the “Embden- Meyerhof-Parnas” (EMP) Pathway.

Pyruvate oxidation (linking reaction)

• During this linking reaction, two stages are connected so that the end product of glycolysis can be used in the citric acid cycle.
• The enzyme pyruvate translocase assists in the entry of the two pyruvate molecules into the mitochondrial matrix. 
• Acetyl-CoA is formed by the oxidation of pyruvate by the Pyruvate dehydrogenase complex.

Citric acid/Krebs cycle

• Citric acid is produced by combining Acetyl-CoA with four-carbon oxaloacetate.
• ATP and carbon dioxide are produced sequentially, along with NADH and FADH reduced forms.
• It is also known as the TCA cycle (tricarboxylic acid cycle) because citric acid has three carboxyl groups.

Electron Transport Chain (ETC)

• This last stage of aerobic respiration occurs in the mitochondria. 
• ETC is a cluster of proteins that transports electrons across a membrane into mitochondria and generates a significant amount of ATP.
• One glucose molecule is broken down into 32 molecules of ATP during this aerobic respiration process.

Examples of Aerobic Respiration

• All multicellular species, including humans, birds, animals, and insects, partake in aerobic respiration. The glucose in the food breaks down in the presence of oxygen and releases energy. 
• It occurs in the majority of higher plants also.

Do all human cells carry out aerobic respiration?

All the cells in the human body are capable of doing aerobic respiration. However, during intense physical activity such as running, jogging, jumping rope, aerobic dance, and cycling up hills, where low oxygen levels result in low energy levels in the body, muscle cells can do anaerobic respiration. To obtain energy, the muscle cells resort to anaerobic respiration.

Aerobic Respiration in Plants

• In the cytosol and mitochondria of plant cells, aerobic respiration takes place.
• Oxygen and simple carbohydrates such as glucose function as reactants. 
• The stomata, which are pores in the epidermis of a plant’s stem and leaves, allow oxygen to enter the plant while it is engaged in aerobic respiration. 
• With the assistance of ambient oxygen, glucose completely breaks down to produce carbon dioxide and water. 
• Additionally, a significant amount of energy is released in the form of ATP.

Significance of Aerobic Respiration

• Living things require ATP that is produced during aerobic respiration to participate in metabolic processes and perform necessary bodily functions.
• Carbon dioxide, the by-product of aerobic respiration, can be used for photosynthesis in green plants. 
• Water, carbon dioxide, and sunlight can be combined during photosynthesis to produce food for plants. 
• Cell division also uses the energy that is generated during respiration.
• The intermediate compounds, organic acids, and coenzymes are useful for organic activities.

Summary

During aerobic respiration, glucose present in the food is converted into water and \(C{O_2}\). When glucose is completely burned, carbon dioxide and water are released as by-products along with energy. The process of aerobic respiration involves four major steps with intermediate reactions. Those are glycolysis, pyruvate oxidation, Krebs’s cycle, and the electron transport chain. In the cytosol and mitochondria of plant cells, aerobic respiration takes place.  Carbon dioxide, the by-product of aerobic respiration, can be used for photosynthesis in green plants.

Frequently Asked Questions

1. Which respiration process transforms glucose into energy more efficiently, and why?
Ans. The 36 ATP molecules are produced by aerobic cell respiration. The efficiency of aerobic cell respiration is about 18 times greater than that of anaerobic cell respiration. Due to the entire conversion of glucose into \(C{O_2}\) and energy, there is a significant amount of energy production.

2. What are ATP and NADH?
Ans. Adenosine triphosphate, or ATP, is an energy-carrying molecule that fuels the metabolism of living things. Nicotinamide adenine dinucleotide, or NAD, is an electron acceptor; its reduced version is called NADH.

3. What is the difference between breathing and cellular respiration?
Ans. While cellular respiration is a process of obtaining energy to carry out various bodily tasks, breathing is a process of exchanging gases between the environment and an organism.

4. Does anaerobic respiration takes place in the human cells?
Ans.  During heavy workouts, anaerobic respiration takes place in the muscles. Since there is no complete breakdown of glucose in anaerobic respiration, the energy liberated is less than that of aerobic respiration. The muscles accumulate lactic acid when you exercise vigorously. Then, this lactic acid oxidizes to produce water and \(C{O_2}\).

5. Where does oxygen-assisted respiration occur within the cell?
Ans. The cytoplasm of the cell serves as the starting point for aerobic respiration, which concludes in the mitochondria. The mitochondria are where the majority of aerobic respiration’s reactions take place.

Introduction

Viruses are small highly contagious creatures which live on the threshold of life and death. The most distinguishing characteristic of viruses is to multiply inside the living cells of other species. When this virus enters our bodies, it affects our immune systems, hence weakening us. When viruses enter our body they use the host mechanism to carry out their life process, as a result, the host(human) does not get the required energy and becomes weak. Viruses such as HIV majorly infect the cells of the immune system making them more susceptible to various other diseases.

HIV

HIV stands for Human Immunodeficiency Virus and is a small virus which belongs to a group of viruses known as retroviruses. This organism is the cause of AIDS. Human immune cells, also referred to as white blood cells(specifically the Helper T Cells), get infected by HIV, hence compromising the host’s immunity. 

Process of infection of HIV

The HIV infection occurs when the blood of the infected person mixes with the blood of the healthy person. A virus enters the body following is the process of infection.

• When HIV first enters a person’s body, it locates and attaches to CD4 lymphocytes, which are essentially fighting cells  of the immune system.
• The virus attaches and then releases its RNA into the cell.
• The retroviruses then synthesis DNA from RNA by the  enzyme reverse transcriptase.
• The viral DNA fuses with the lymphocyte’s cellular DNA and becomes a part of the genetic makeup of the cell.
• The virus now creates a large number of its own copies using the cell’s replication system, which are then released into the blood to infect additional CD4 cells.

As the body number of CD4 cells in the body decreases due to the infection, the body becomes immunodeficient.

AIDS	HIV
AIDS stands for Acquired Immunodeficiency Syndrome.	HIV stands for Human Immunodeficiency Virus.
AIDS is caused by Human Immunodeficiency Virus.	HIV is a virus that causes diseases.
AIDS is an immunodeficiency syndrome and is the last stage of HIV infection.	The virus infects the immune system and hence compromises the immune system of the host.
Patients show very severe symptoms.	Patients experience minor symptoms during acute and chronic infection stages.
Symptoms include- Breathlessness, lack of strength, swelling in groin regions, getting sick very easily, etc.	Symptoms are- Fever, nausea, body ache, stomach ache, etc.
It is incurable and fatal	Its infection can be controlled to some extent with the help of medicines.

Summary

AIDS is currently quite common disease around the world. This condition is frequently taboo and not discussed in many societies, which unintentionally hastened its rapid global expansion. AIDS and HIV are frequently mistaken for one another, leading to their interchangeability. Despite being closely linked, they are not one and the same. It is important to note that AIDS  is not particularly contagious on its own, which means that it cannot travel quickly through regular channels like air, water, etc. Hugs, sneezes, saliva, sweat, or proximity to infected people do not spread it. 

Frequently Asked Questions

1. Explain detection of AIDS by ELISA Test?
Ans: Enzyme-Linked Immunosorbent Assay,  known as ELISA, is a technique for identifying HIV infection. A  viral protein antigen has already been generated in a laboratory. This antigen is placed in the cassette along with the blood sample of the patient. If the blood has viral antibodies, they attach to the antigen and coagulate hence modifying the look of the cassette’s contents which detects the presences of virus in the blood sample.

2. How is AIDS treated?
Ans: Antiretroviral therapy, generally known as ART, is a form of treatment for AIDS but is not a cure. It has a combination of three distinct drugs. It lengthens the afflicted person’s life span.

3. What distinguishes an antigen from an antibody?
Ans: Foreign chemicals are known as antigens and they have the power to infect the body and cause a disease. Pathogens frequently contain them. 

Immune cells create immunoglobulins called antibodies to fight off particular antigens which are present in the host body cells.