Life Processes Class 10: Important Questions & Answers

1. Why does a plant need both photosynthesis and respiration?

1. 1Photosynthesis captures light energy to make organic food from carbon dioxide and water.
2. 2Respiration releases usable energy from food for cell activities. Plants respire during day and night; photosynthesis requires suitable light.

2. How do villi support absorption in the small intestine?

1. 1Villi and their fine projections provide a large surface area. Their thin lining provides a short transfer distance.
2. 2Blood vessels carry absorbed nutrients away; lacteals help transport absorbed fats. This maintains transport from the intestine to the rest of the body.

3. Compare aerobic respiration with fermentation in yeast

1. 1Aerobic respiration uses oxygen and typically breaks down glucose more completely, releasing carbon dioxide, water and usable energy.
2. 2In yeast without oxygen, fermentation produces ethanol and carbon dioxide and yields less usable energy per glucose molecule.

4. Distinguish xylem from phloem

1. 1Xylem transports water and dissolved minerals, mainly from roots towards the rest of the plant.
2. 2Phloem transports sugars from sources, such as mature leaves, to sinks that use or store them. Transport can occur in different directions in different sieve tubes.

5. Why is the left ventricle muscular?

1. 1It pumps blood through the systemic circuit to the body.
2. 2Its thick muscular wall produces the pressure needed for that longer circulation. The right ventricle pumps to the lungs.

6. Trace a complete circuit of blood

1. 1Body → venae cavae → right atrium → right ventricle → pulmonary artery → lungs.
2. 2Lungs → pulmonary veins → left atrium → left ventricle → aorta → body.
3. 3Arteries carry blood away from the heart, not always oxygen-rich blood. The pulmonary artery is the key counterexample.

7. What happens in a nephron after filtration?

1. 1Small substances pass from blood into the filtering space; blood cells and most large proteins remain in the blood.
2. 2Useful substances and much of the water are reabsorbed along the tubule. Tubular secretion also helps adjust the filtrate.
3. 3The remaining fluid contributes to urine. The kidneys help regulate water and ion balance as well as remove wastes.

8. How is excretion different from egestion?

1. 1Excretion removes metabolic wastes produced by cells, such as urea.
2. 2Egestion removes undigested material from the digestive tract. Not everything leaving the body is a metabolic waste.