CBSE Class 10 Biology Life Processes Worksheet Set A

Short Answer :

Question. What would be the consequences of a deficiency of haemoglobin in our bodies?
Answer: If haemoglobin content is reduced in blood, its oxygen carrying capacity decreases. So the person shows symptoms of deficient oxygen such as breathlessness and lack of energy. The person looks pale and loses weight. This condition is called anaemia.

Question. (i) Which organ secretes a hormone when the blood sugar rises? Name a digestive enzyme released by this organ.
(ii) Why pancreas helps in digestion and also regulates blood sugar? 
Answer: (i) Pancreas secretes insulin (hormone) when the blood sugar rises. Pancreas secretes pancreatic juice which contains digestive enzymes.
(ii) Pancreas secretes enzymes like pancreatic amylase which breaks down starch, trypsin which breaks down proteins and lipase breaks down emulsified fats.
Pancreas also secretes a hormone called insulin which controls the metabolism of sugar. Therefore it lowers the blood sugar level. So pancreas is both an exocrine and an endocrine gland.

Question. Give reasons for the following:
(a) Arteries are thick walled.
(b) Blood goes only once through the heart in fishes.
(c) Plants have low energy needs. 
Answer: (a) Arteries have thick walls because these vessels carry blood from the heart to all the parts of the body and blood emerges from the heart under high pressure.
(b) A fish has a two chambered heart and has gills to oxygenate blood. In a fish, the heart pumps deoxygenated blood to gills where oxygenation of blood takes place. The oxygenated blood from the gills is supplied to the body parts of the fish where oxygen is utilised and carbon dioxide enters into it, making it deoxygenated. This deoxygenated blood returns to the heart to be pumped into gills again. Thus blood passes through the heart of fish only once in one complete cycle.
(c) Plants are fixed at a place and do not show any locomotion. Plants are less active. Their cells do not need to be supplied with materials so quickly. Therefore plants have low energy needs and respire at a slow rate.

Question. (a) State the purpose of formation of urine. 
(b) What will happen if there is no tubular reabsorption in the nephrons of kidney?
Answer: (a) • Urea is produced as a waste by decomposition of unused proteins in the liver. Our body must get rid of these waste materials because their accumulation in the body is poisonous and harmful for us.
• Kidneys are the organs which remove the poisonous substance urea, other waste salts and excess water from the blood and excrete them in the form of a yellowish liquid called urine.
(b) During filtration, the substances like glucose, amino acids, salts, water and urea etc. present in the blood pass into Bowman’s capsule and then enter the tubule of nephron. When the filtrate containing useful substances as well as the waste substances passes through the tubule, the useful substances like glucose, amino acids, most salts and most water etc. are reabsorbed into blood through blood capillaries surrounding the tubule. Only the waste substances like urea, some unwanted salts and excess water remain behind in the tubule. Therefore, reabsorption in the nephrons of kidneys is important.

Question. (i) Name two waste products which are stored in old xylem in plants.
(ii) Name the process by which plants get rid of excess water. Name the pores through which this process takes place. 
Answer: (i) Resin and gums are the two wastes which are stored in old xylem in plants.
(ii) • Transpiration is the process by which plants get rid of excess water.
• Stomatal pores are the pores through which transpiration takes place.

Question. Describe the process of anaerobic respiration.
Answer: The respiration which takes place in the absence of oxygen is called anaerobic respiration.
During this respiration glucose is broken down into ethyl alcohol and CO2 with the release of very small amount of energy. In anaerobic respiration one molecule of oxygen produces only 2 ATP molecules of energy. This type of respiration occurs in microscopic organisms like yeast, bacteria, etc.
In human beings, the energy is obtained by aerobic respiration but sometimes anaerobic respiration occurs in the muscles during vigorous exercise when oxygen gets consumed at a faster rate than its supply by the blood. During the anaerobic respiration in the muscles the glucose is converted into lactic acid with the release of 2 ATP molecules of energy.
Anaerobic respiration in human beings:

Question. Explain how water and minerals are transported in plants? 
Answer: Most plants secure their water and minerals from their roots. Minerals travel dissolved in water. Water and minerals are transported through xylem cells from the soil to the leaves. The xylem cells of roots, stem and leaves are interconnected to form a conducting channel. The root cells take ions from the soil. This creates a difference between the concentration of ions of roots and soil. Therefore, there is a steady movement of water into xylem. An osmotic pressure is formed and water and minerals are transported form one cell to the other due to osmosis. The continuous loss of water takes place due to transpiration.

Question. Describe the structure and functioning of nephron. 
Answer: Structure of nephron. Nephron is the basic filtration unit in the kidney. It consists of a tubule which is connected with a collecting duct at one end and a cup shaped structure at the other end, called Bowman’s capsule. Every Bowman’s capsule contains a cluster of capillaries called glomerulus within the cup-shaped structure. The blood enters into glomerulus through afferent arteriole of renal artery and leaves it through efferent arteriole.
Basic functions of Nephrons:
(i) Filtration. Filtration of the blood takes place in Bowman’s capsule in the capillaries of the glomerulus.
Then this filtrate passes into the tubular part of the nephron. The filtrate contains glucose, amino acids, urea and uric acid and a large amount of water.
(ii) Reabsorption. The filtrate flows along the tubule and useful substances such as glucose, amino acids, salts and some water are re-absorbed into the blood by the capillaries surrounding the nephron tubule.
(iii) Urine. The filtrate which remains after the re-absorption is called the urine, which is collected from nephron by the collecting duct to carry it to the urinary bladder and then to the urethra.

Question. (a) What happens to the heart when muscles work harder? 
(b) Which body system is directly affected when a person has heart disease?
(c) Which cells increase in number during infection?
Answer: (a) When muscles work harder, the heart beats faster because the muscles need more energy than the normal requirement. The faster beating of heart pumps blood more rapidly to the muscles which supplies more oxygen to the muscle cells for rapid respiration to produce more energy.
(b) Human circulatory system is directly affected when a person has heart disease.
(c) White blood cells (WBCs) increase in number during infection.

Question. The rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms. Give reason. State the pathway of air from nostrils to the lungs in human beings. 
Answer: The animals which live in water (aquatic animals) use the oxygen dissolved in water to carry out respiration. Since the amount of dissolved oxygen in water is low as compared to the amount of oxygen in the air, therefore, the rate of breathing in aquatic animals is much faster than in terrestrial animals. A faster rate of breathing provides more oxygen to aquatic animals. Pathway of air in human beings:
Nostrils → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Lungs

Question. Explain the nutrition process in Amoeba.
Answer: Amoeba takes in the food particles with the help of its finger like projections called pseudopodia. Inside its cell a food vacuole is formed around the food particle. Inside the food vacuole, complex substances are broken down into simpler ones which are then diffused into the cell cytoplasm. The remaining undigested material is sent to the surface of the cell and thrown out. This process of nutrition in Amoeba is called Endocytosis.

Question. Bile juice does not contain any enzyme but bile salts are important for digestion and absorption of fats. State reason. 
Answer: Bile is a digestive juice secreted by the liver. Although it does not contain any digestive enzymes, it plays an important role in the digestion of fats.
Bile is alkaline and contains salts which help to emulsify or break the fats (or lipids) present in the food.
Thus, bile performs two functions:
(i) Makes the acidic food coming from the stomach alkaline so that pancreatic enzymes can act on it.
(ii) Bile salts break the fats present in the food into small globules making it easy for the enzymes to act and digest them.

Question. (a) State reason for the following: 
(i) Rings of cartilage are present in the trachea.
(ii) Plants look green in colour.
(b) Write other names of the following:
(i) Alveolar sac (ii) Voice box
Answer: (a) (i) The air coming from the nostrils during breathing passes through the trachea. The trachea does not collapse even when there is no air in it because it is supported by rings of soft cartilages.
(ii) Plants look green in colour because of the presence of a green pigment called chlorophyll in their chloroplasts.
(b) (i) Alveolar sac → Alveoli
(ii) Voice box → Larynx