Class 10 life processes important questions

1. What are enzymes? Name any one enzyme of our digestive system and write its function.

Answer. Enzymes are biological catalysts. Catalysts are proteins that increase the rate of chemical reactions without being used up.  

For example: Amylase catalyses the breakdown of starch into sugars in the mouth and small intestine 

 

 2. (i) Write the balanced chemical equation for the process of photosynthesis,

 Answer. 

Photosynthesis can be represented using a chemical equation. The overall balanced equation is 

                     6CO₂  +  12H₂O          ^Sunlight              C₆H₁₂O₆ + 6H₂0 + 6O₂ 

 (ii) When do the desert plants take up carbon dioxide and perform      photosynthesis?  

Answer.  

Desert plants open up their stomata during night and take in CO₂. Stomata remains close during the day time to prevent the loss of water by transpiration. They store the CO₂ in their cells until the sun comes out and they can carry on with photosynthesis during the day time.  

   

3. In single celled organisms diffusion is sufficient to meet all their requirements of food, exchange of gases or removal of wastes but it is not in case of multicellular organisms. Explain the reason for this difference.

Answer.  

Unicellular organisms can absorb sufficient oxygen because of its complete contact with the atmosphere, but in multicellular organisms the rate of absorption and diffusion becomes very less because all cells are not in direct contact with the atmosphere. Multicellular organisms require greater amount of oxygen to sustain life processes which cannot be fulfilled by the process of diffusion.  

 

4. Name the acid presents in the following:  

(i) Tomato (ii) Vinegar (iii) Tamarind Answer. 

(i)                Oxalic acid: Oxalic acid is an organic compound found in many plants. These include leafy greens, vegetables, fruits, cocoa, nuts and seeds 

(ii)              Citric acid: Citric acid is found naturally in citrus fruits, especially lemons and limes. It's what gives them their tart, sour taste.  

(iii)            Tartaric acid: Tartaric acid is a white, crystalline organic acid that occurs naturally in many fruits, most notably in grapes, but also in bananas, tamarinds, and citrus. 

5. State the role of the following in human digestive system:  

(i) Digestive enzymes (ii) Hydrochloric acid (iii) Villi Answer. 

(i)  Digestive enzymes – Foods need to be broken into their small or simpler molecules so that they can be absorbed into the bloodstream. However, the physical breakdown of food is not enough. Enzymes are hence needed for the chemical breakdown of food and speeding up the digestive process. The products of digestion can hence be small enough to be absorbed. 

(ii)   Hydrochloric acid – Hydro chloric acid helps to kill the germs which might have entered in to the system through food. It creates acidic medium for the pepsin to act on food to breakdown proteins.  

(iii) Villi – Villi are finger like projections in the small intestine. They help to increase the surface area for absorption of the digested food. Villi are richly supplied with blood vessel which help to absorb digested food in to the blood stream. 

  

6. (a) Explain how does the exchange of gases occur in plants across the surface of stems, roots and leaves.  

Answer  

(a)   In plants there are tiny pores called stomata on leaves and lenticels in stem which facilitate the exchange of gases. Carbon dioxide is taken in and oxygen given out {during photosynthesis} and vice versa during respiration. 

(b)  How are water and minerals transported in plants?  

Answer  

    (b) Water and minerals are transported within the plant by the Xylem                  vessels (mainly in an upward direction); these are part of the vascular              system which also includes Phloem vessels. 

        Phloem transports the products of photosynthesis within the plant, to all          parts like the stem, roots, fruits etc. in all directions. 

7. Mention the raw materials required for photosynthesis. 

Answer.  

The following raw materials are required for photosynthesis: 

(i) Carbon Dioxide: Plants get CO₂ from atmosphere through stomata. 

(ii)Water: Plants absorb water from soil through roots and transport to leaves. 

(iii) Sunlight: Sunlight, which is absorbed by the chlorophyll and other green parts of the plant.  

8. Why do herbivores have longer, small intestine than carnivores?  

Answer.  

Digestion of cellulose takes a longer time. Hence, herbivores eating grass need a longer small intestine to allow complete digestion of cellulose. Carnivorous animals cannot digest cellulose due to the absence of enzyme CELLULASE, hence they have a shorter intestine.

9. Write correct sequence of four steps of method for the preparation of temporary mount of a stained leaf peel. 

Answer.  

Take a healthy leaf from the potted plant. 

1.     Remove a part of the peel from the lower surface of the leaf. You can do this by folding the leaf over and gently pulling the peel apart using forceps. 

Keeps the peel in a watch glass containing water. 

                                                    

2.     Put a few drops of safranin stain in a watch glass. 

 

3.     After 2-3 minutes take out the peel and place it on a clean glass slide. 

 

4.     Put a drop of glycerin over the peel and place a clean covers lip gently over it with the help of a needle. 

 

5.     Remove the excess stain and glycerin with the help of blotting paper. 

 

6.     Observe the slide under magnifications of the compound microscope.