NCERT Solutions

Class 10 science

life processes

Q1) The kidneys in human beings are parts of the system for

  1. Nutrition
  2. Respiration
  3. Excretion
  4. Transpiration

Answer:

(c)Excretion

Q2) The xylem in plants are responsible for

  1. transport of water
  2. transport of food
  3. transport of amino acids
  4. transport of oxygen

Answer:

(a)transport of water

Q3) The autotrophic mode of nutrition requires

  1. carbon dioxide and water
  2. chlorophyll
  3. sunlight
  4. all of the above

Answer:

(d)All the above

Q4) The breakdown of pyruvate to give carbon dioxide, water and energy takes place in

  1. ctyoplasm
  2. mitochondria
  3. chloroplast
  4. nucleus

Answer:

(d)All the above

Q5)How are fats digested in our bodies? Where does this process take place?

Answer:
Digestion of fats takes place in small intestine. Fats entering in intestine are in the form of large globules. Bile juice breaks down these large globules into smaller globules. Afterwards fat digesting enzyme lipase present in pancreatic juice and intestinal juice converts it into fatty acids and glycerol.

Q6) What is the role of saliva in the digestion of food?

Answer:
The role of saliva in the digestion of food:
? It moistens the food for easy swallowing.
? It contains a digestive enzyme called salivary amylase, which breaks down starch into sugar.

Q7) What are the necessary conditions for autotrophic nutrition and what are its by-products?

Answer:
Autotrophic nutrition takes place through the process of photosynthesis. Carbon dioxide, water, chlorophyll pigment, and sunlight are the necessary conditions required for autotrophic nutrition. Carbohydrates (food) and O2 are the by-products of photosynthesis.

Q8) What are differences between aerobic and anaerobic respiration? Name some organisms that use anaerobic mode of respiration.

Answer:
Difference between aerobic and anaerobic respiration:

Aerobic Respiration Anaerobic Respiration
Requires oxygen Occurs in the cytoplasm of cells
Occurs in mitochondria of cells Doesn't require oxygen
Produces a lot of ATP per glucose molecule Used during the first 1-2 minutes of exercise
Used when heart rate and breathing rate rise Produces less ATP per glucose molecule

Anaerobic respiration takes place in yeast, some bacteria and some internal parasites like tapeworm.

Q9) How are the alveoli designed to maximize the exchange of gases?

Answer:
The alveoli are thin walled and richly supplied with a network of blood vessels to facilitate exchange of gases between blood and the air filled in alveoli. They have balloon – like structure that provide maximum surface area for exchange of gases.

Q10) What would be the consequence of a deficiency of hemoglobin in our bodies?

Answer:
Haemoglobin is a pigment present in RBC. It has a high affinity for oxygen. It carries oxygen from lungs to various tissues which are deficient in oxygen. Presence of less hemoglobin will result in less supply of oxygen to tissues. A person having less hemoglobin will get tired soon and will have a pale look.

Q11) Describe double circulation in human beings. Why is it necessary?

Answer:
In mammals and birds the blood goes through the heart twice during each cycle. This is known as double circulation. Deoxygenated blood which enters right auricle and then it enters the right ventricle from where it is pumped to lungs for oxygenation. From lungs after oxygenation it comes to left auricle and then enters left ventricle from where it is pumped to various parts of body. Such system of circulation does not allow mixing of oxygenated and deoxygenated blood which allows efficient supply of oxygen to the body.

Q12) What are differences between the transport of materials in xylem and phloem?

Answer:

Transport of materials in xylem Transport of materials in pholem
Xylem tissue helps in the transport of water and minerals. phloem tissue helps in the transport of food
Water is transported upwards from roots to aerial parts of plants. food is transported both upward and downward directions.
Transport in xylem requires physical forces such as transpiration pull Transport of food in phloem requires energy in the form of ATP.

Q13) Compare the functioning of alveoli in the lungs and nephron in the kidneys with respect to their structure and functioning.

Answer:

Alveoli Nephrons
Structure structure
Alveoli are tiny balloon-like structures present inside the lungs Nephrons are tubular structures present inside the kidneys.
The walls of the alveoli are one cell thick and it contains an extensive network of blood cappillaries Nephrons are made of glomerulus,bowmann's capsule,and a long renal tube
Alveoli Nephrons
Function Function
The exchange of O2 and CO2 takes place between the blood of the capillaries that surround the alveoli and the gases present in the alveoli. The blood enters the kidneys through the renal artery.The blood is entered here and the nitrogeneous waste in the form of urine is collected by collecting duct.
Alveoli are the site of gaseous exchange Nephrons are the basic filtaration unit.