1. The kidneys in human beings are a part of the system for

(a) nutrition

(b) respiration.

(c) excretion.

(d) transportation

excretion

2. The xylem in plants are responsible for

(a) transport of water .

(b) transport of food.

(c) transport of amino acids.

(d) transport of oxygen.

transport of water 

3. The autotrophic mode of nutrition requires

(a) carbon dioxide and water.

(b) chlorophyll.

(c) sunlight.

(d) all of the above.

All of the above

4. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in

(a) cytoplasm.

(b) mitochondria.

(c) chloroplast.

(d) nucleus

mitochondria

5. How are fats digested in our bodies? Where does this process take place?

Fat digestion takes place in the small intestine. Fats are present in the small intestine in the form of large globules. The large globules of fats are broken down into smaller globules by the process of emulsification. this is carried out  by bile salts. Bile is the secretion of liver. Now the emulsified fats are broke down by the  pancreatic juice  secretes by pancreas which contains lipase. The enzymes in intestinal juice finally converts these fats into fatty acids and glycerol.

6. What is the role of saliva in the digestion of food?

Food enters our mouth and gets crushed by our teeth. The fluid called saliva secreted by the salivary glands wets this food to make its passage smooth. Salivaryamylase, an enzyme in saliva, breaks starch (a complex molecule) into simple sugar. The saliva mixes the food well.

7. What are the necessary conditions for autotrophic nutrition and what are its byproducts?

Autotrophic nutrition takes place through the process of photosynthesis. Necessary conditions required for autotrophic nutrition are carbon dioxide, water, chlorophyll pigment, and sunlight. Carbohydrates and

$O_2$

 are the by-products of photosynthesis.

8. What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration?

9. How are the alveoli designed to maximize the exchange of gases?

Alveoli are tiny air sacs in our lungs. It is found in large number inside lungs. It allows gas exchange to occur simultaneously over a large area. Also walls of alveoli contain an extensive network of blood vessels. This allows for easy transport of oxygen and carbon dioxide. Walls of alveoli are extremely thin and made of single layer of cells.

10. What would be the consequences of a deficiency of hemoglobin in our bodies?

The hemoglobin is an important component in our blood which helps to conduct the oxygen in our body. So that hemoglobin deficiency will affect the oxygen supply capacity of blood leads to deficiency of oxygen in the body cells. It can also lead to a disease called anaemia.

11. Describe double circulation of blood in human beings. Why is it necessary?

Inside human circulatory system, double circulation occurs. During double circulation blood goes twice in the heart in a single cycle. Double circulation consist of two steps:

1. Pulmonary circulation.

2. Systemic circulation.

Pulmonary Circulation

This happens between the heart and lungs.  The right ventricle pumps deoxygenated blood into the lungs.  From lungs it is oxygenated. Now this oxygenated blood flows to the left atrium, and pumped into the left ventricle. 

Systemic circulation

This happens between heart and the other organs. The oxygenated blood is pumped to various parts of the body from the left ventricle. The deoxygenated blood from different parts of the body carried through vena cava and reach right atrium. The right atrium transfers the blood into right ventricle.

12. What are the differences between the transport of materials in xylem and phloem?

13. Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.

Pg. No. 95

1. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?

The stucture of our body is huge and they are complex in nature. All our cells requires oxygen. But diffusion is a process that is very slow. So it will take a lot of time to reach each and every cell of the body.

2. What criteria do we use to decide whether something is alive?

If the fundamental life processes like nutrition, respiration, transportation, excretion, control and coordination, growth, and reproduction occurs normally then the organism is considered living.

3. What are outside raw materials used for by an organism?

Food, water, and oxygen are the outside raw materials that are used by an organism. Requirement for the raw materials vary based on the on the complexity of the organism and the environment it is living.

4. What processes would you consider essential for maintaining life?

Life processes like nutrition, respiration, transportation, excretion, and control, and coordination are essential for maintaining the life. 

Pg. No. 101

1. What are the differences between autotrophic nutrition and heterotrophic nutrition?

2. Where do plants get each of the raw materials required for photosynthesis?

The raw materials required for photosynthesis are sunlight, water, carbon dioxide, and chlorophyll.

• CO₂ is obtained from atmosphere through stomata
• Water and Nutrients are absorbed from soil by plant roots.
• Sunlight from nature

3. What is the role of the acid in our stomach?

The acid present in our stomach is HCl. It dissolves food particles. It activate various digestive enzymes. In the acidic medium, the enzyme pepsinogen is activated and then converted to pepsin.

4. What is the function of digestive enzymes?

Main function of digestive enzyme is to break down of complex food molecules into simpler food molecules. By doing this cells can absorb the food easily and can transport to various part of our body.

5. How is the small intestine designed to absorb digested food?

With the help of micro villi, small intestine can absorb the food.  It increases the surface volume which make absorption more effective. Inside micro villi one can find numerous blood vessels which absorbs the digested food and carry it to blood stream. Blood transports food to each part of our body. 

Pg. No. 105

1. What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?

Aquatic organisms consume oxygen dissolved in water, while terrestrial organisms utilize atmospheric oxygen. When compared to oxygen in water, the level of oxygen in the atmosphere is high. 

2. What are the different ways in which glucose is oxidized to provide energy in various organisms?

3. How is oxygen and carbon dioxide transported in human beings?

(i) Humans breathe in oxygen through their noses and reach the lungs with it.
(ii)  From the alveoli, O2 is taken up by the red blood cells present in the blood capillaries.
(iii) And, the CO2 from the various tissues is transported to the alveoli. (iv) This CO2 is then released through the nasal passage during exhalation. Alveoli are the sites of exchange of gases.

4. How are the lungs designed in human beings to maximize the area for exchange of gases?

Human lungs are shaped to maximize gas exchange. Lungs contain millions of alveoli which provide a surface for the exchange of gases. 

Pg. No. 110

1. What are the components of the transport system in human beings? What are the functions of these components?

The components of the transport system in human beings are Heart, blood and blood vessels. 

Heart pumps oxygenated blood throughout the body and it receives deoxygenated blood from the various parts of our body. This impure blood is send to the lungs for oxygenation.

Blood: It transports oxygen, nutrients, CO2, and nitrogenous wastes.

Blood vessels are of two types: arteries and veins. Main function of blood vessel  is to carry the blood through cells, tissues and organs.

2. Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?

Mammals and birds are  warm-blooded animals. They can control their body temperature without depending on environment. Because of this both birds and mammals requires  lot of oxygen to produce more energy to balance their body temperature. So, it is required to have separate oxygenated and deoxygenated blood to supply the required amount of oxygen.

3. What are the components of the transport system in highly organized plants?

Transport system of highly organized plants consists of vascular tissue, namely xylem and phloem. Function of  Xylem is to carry water and minerals from root to the aerial parts of plants. Function of  Phloem is to carry the manufactured foods from leaves to the other parts of the plants.

4. How are water and minerals transported in plants?

Water and minerals are absorbed from soil by root hairs by the process of osmosis.  Roots absorb the water from the soil by actively taking up ions. This creates a difference in the concentration of ions between the root and the soil. The water moves up creating a column of water that is steadily pushed upwards in vessels and tracheids of the roots, stem and leaves, and are interconnected to form a continuous system of water-conducting channels reaching all parts of the plant. The water loss by leaves through stomata is called transpiration. It creates a suction pull, which pulls water from the xylem cells of roots.

5. How is food transported in plants?

Food transportation in plants are carried out with the help of Phloem. The transportation of food in phloem utilizes the energy from ATP. It will helps in creating osmotic pressure. his pressure moves the materials in phloem to the tissues. 

Pg. No. 112 

1. Describe the structure and functioning of nephrons

Nephrons are the filtering unit of kidneys. Nephron consist of a  cup shaped bowman’s capsule at the upper end and tubule at the lower end. One end of tubule is connected to bowman’s capsule other end to urine collecting duct of the kidney. Bowman’s capsule consists of Glomerulus. Main function of  nephron is to filter the blood passing through kidney. Nephrons are also known as excretory/ filtration unit. 

2. What are the methods used by plants to get rid of excretory products?

Plants do not have excretory systems like in animals. Plants uses the method of transpiration to get rid of the excess water. Some liquid and solid wastes are stored in the barks, leaves and fruits. To get rid of the waste products stored here, they shed their leaves, peeling of bark etc. Many plant waste products are stored in cellular vacuoles. Wastes like gum, resins etc. are stored in dead cells of old xylem tissues. Plants also excrete some waste substances into the soil around them.

3. How is the amount of urine produced regulated?

Amount of urine produced depends upon the water present in our body. If excess water present then urine produced is more. Amount of urine produced also depends on the amount  of dissolved waste present in the body, environmental factors and ADH hormone.