CBSE Class 10 Science HOTs Life Processes Set 04

Question. What are the components of the transport system in human beings? What are the functions of these components?
Answer: In human beings, for the transport of various substances, a well-developed circulatory system is present. Main components of circulatory system are Heart, blood vessels and blood.
Heart: It pumps the blood and circulate the blood in the whole body continuously.
Blood vessels: Arteries are thick blood vessels which carry oxygenated blood from the heart to all the parts of the body. Veins are thin walled blood vessels which carry deoxygenated blood from all the parts of the body back to the heart. Capillaries are thin and narrow blood vessels in which exchange of material between the blood and surrounding cells takes place.
Blood: It acts as a connective tissue which transport food, oxygen, waste materials, hormones, etc. from one part of the body to another.

Question. Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
Answer: Mammals and birds are warm blooded animals. This means they can control their body temperature and they need not to depend on environment for body temperature regulation. Because of this birds and mammals need optimum oxidation of glucose which is possible with good supply of oxygen without mixing of oxygenated and deoxygenated blood.

Question. What are the components of the transport system in highly organised plants?
Answer: The main components of transport system in highly organised plants are two conducting tissues called xylem and phloem.
• Xylem consists of vessels and tracheids.
• Phloem consists of sieve tubes and companion cells.

Question. How are water and minerals transported in plants?
Answer: Mechanism of Transport of Water and Minerals in a Plant:
• The vessels and tracheids of roots, stems and leaves in xylem tissue are interconnected to form a continuous system of water-conducting channels reaching all parts of the plant.
• The cells of the roots in contact with the soil actively take up ions which creates a difference in the ion concentration between the root and the soil.
• Thus, there is steady movement of water into root xylem from the soil, creating a column of water that is pushed upwards.
• Plant uses another strategy to move water in the xylem upwards to the highest points of the plant body.
• The water which is lost through the stomata is replaced by water from the xylem vessels in the leaf.
• Evaporation of water molecules from the cells of a leaf creates a suction which pulls water from the xylem cells of roots.
• This loss of water is transpiration which helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves.
• Transpiration becomes the major driving force in movement of water in the xylem during the day when the stomata are open.
• This mechanism is also known as cohesion of water theory or transpiration pull.

Question. How is food transported in plants?
Answer: In the plants, the food is transported through phloem to the storage organs like roots, fruits, seeds and growing parts. This process is called translocation. In the phloem, sieve tubes are present, which with the help of companion cells, translocate food both in upward and downward directions. For the translocation, energy is required which is provided by ATP.

Question. What are the methods used by plants to get rid of excretory products? 
Answer: Plants get rid of carbon dioxide and oxygen through diffusion. Old branches and leaves are shed off when they become useless. Plants have a mechanism to release some waste products through roots also. Some waste products are deposited near bark as raisins or gums.

Question. How is the amount of urine produced regulated?
Answer: The kidney is equipped with a mechanism to reabsorb water from the filtrate. This depends on how much water is left in the body and in the filtrate. The comparative concentration of water gives a signal to the brain which then takes the required corrective action of either reabsorbing water or releasing more water. Thus, the amount of urine formation is regulated by kidneys.

NCERT EXERCISES

Question. The kidneys in human beings are a part of the system for
(a) nutrition.
(b) respiration.
(c) excretion.
(d) transportation.
Answer: (c) excretion.

Question. The xylem in plants are responsible for
(a) transport of water.
(b) transport of food.
(c) transport of amino acids.
(d) transport of oxygen.
Answer: (a) transport of water.

Question. The autotrophic mode of nutrition requires
(a) carbon dioxide and water.
(b) chlorophyll.
(c) sunlight.
(d) all of the options.
Answer: (d) all of the options.

Question. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
(a) cytoplasm.
(b) mitochondria.
(c) chloroplast.
(d) nucleus.
Answer: (b) mitochondria.

Question. How are fats digested in our body? Where does this process take place?
Answer: Fats are digested in our body in the small intestine. Fats entering the small intestine are in the form of large globules. The digestion of fats complete in the following steps:
(i) Bile salts break large globules into small globules.
(ii) Pancreatic juice secreted by pancreas has enzyme lipase which breaks down emulsified fats.
(iii) Enzymes secreted from the walls of small intestine finally converts fats into fatty acids.

Question. What is the role of saliva in the digestion of food?
Answer: Saliva contains water, salts, mucin and an enzyme salivary amylase that breaks down starch present in the food into sugar.

Question. What are the necessary conditions for autotrophic nutrition and what are its by-products?
Answer: The necessary conditions for autotrophic nutrition are as follows:
(i) \( CO_2 \) is necessary for photosynthesis.
(ii) Water is required.
(iii) Sunlight is necessary for photosynthesis.
(iv) Chlorophyll is also essential for photosynthesis.
Oxygen is liberated as a by-product.

Question. What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration. 
Answer:
Aerobic Respiration:
(i) When oxidation of food nutrients occurs in the presence of molecular oxygen, it is called aerobic respiration.
(ii) More energy is produced as oxidation is complete.
(iii) Takes place in cytoplasm and mitochondria.
Anaerobic Respiration:
(i) When oxidation of nutrients occurs without the utilisation of molecular oxygen, it is called anaerobic respiration.
(ii) Less amount of energy is produced as oxidation is not complete.
(iii) Takes place in the cytoplasm.
Anaerobic mode of respiration occurs in some organisms like Bacteria and Yeast.

Question. How are the alveoli designed to maximise the exchange of gases?
Answer: In human beings, to maximise the area for exchange of gases, inner surface of lungs has smaller tubes that terminate into balloon-like structures called alveoli. The walls of alveoli have extensive network of blood vessels.

Question. What would be the consequences of a deficiency of haemoglobin in our bodies?
Answer: Deficiency of haemoglobin in our bodies will affect the supply of oxygen to tissues and cells because haemoglobin is the carrier of oxygen. Thus, a person shows symptoms of breathlessness, tiredness with indications of iron deficiency, i.e. anaemia.

Question. Describe double circulation in blood of human beings. Why is it necessary?
Answer: The circulatory system of man is called double circulation as the blood passes through the heart twice in one complete cycle of the body. It involves two circulations:
(i) Pulmonary circulation: It begins from the right ventricle which expels the blood into the pulmonary trunk. The blood flowing into the vascular system of the lungs, becomes oxygenated and returns to the heart (left atrium) through pulmonary veins.
(ii) Systemic circulation: This circulation starts from the left ventricle which sends the blood into the aorta. The aorta divides into arteries, arterioles and finally to capillaries and thereby, supplies oxygenated blood to various parts of the body. From there deoxygenated blood is collected by venules which join to form veins and finally vena cava and pour blood back into the right auricle of heart.
Necessity of double circulation: The right side and the left side of the human heart are useful to prevent deoxygenated and oxygenated blood from mixing. This type of separation of oxygenated and deoxygenated blood ensures a highly efficient supply of oxygen to the body. This is useful in case of humans because it constantly gives energy to maintain their body temperature.

Question. What are the differences between the transport of materials in xylem and phloem?
Answer:
Xylem:
(i) In xylem, transport of water and minerals occurs from roots to leaves.
(ii) Conduction of water and materials takes place through xylem vessels and tracheids (dead tissues).
Phloem:
(i) In phloem, transport of food occurs from leaves to other parts of plant.
(ii) Conduction of food takes place through sieve tube and companion cells (living cells).

Question. Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.
Answer:
Alveoli in Lungs:
(i) Alveoli are balloon like structures.
(ii) It is made up of one-celled thick wall which contains extensive network of blood capillaries.
(iii) Alveoli are the site of gaseous exchange in lungs.
(iv) Here exchange of oxygen and carbon dioxide takes place between the blood flowing in capillaries which surround the alveoli and gases present in the alveoli.
Nephrons in Kidneys:
(i) Nephrons are long tubular structures.
(ii) It is made up of glomerulus, Bowman’s capsule and a long renal tube.
(iii) Nephrons are the basic filtration unit of kidney.
(iv) Each nephron filters the blood and separates the nitrogenous waste in the form of urine.

SELECT NCERT EXEMPLAR PROBLEMS

Question. Which part of alimentary canal receives bile from the liver?
(a) Stomach
(b) Small intestine
(c) Large intestine
(d) Oesophagus
Answer: (b) Small intestine

Question. When air is blown from mouth into a test-tube containing lime water, the lime water turns milky due to the presence of
(a) oxygen
(b) carbon dioxide
(c) nitrogen
(d) water vapour
Answer: (b) carbon dioxide

Question. The filtration units of kidneys are called
(a) ureter
(b) urethra
(c) neurons
(d) nephrons
Answer: (d) nephrons

Question. The opening and closing of the stomatal pore depends upon
(a) oxygen
(b) temperature
(c) water in guard cells
(d) concentration of \( CO_2 \) in stomata
Answer: (c) water in guard cells

Question. Which of the following statements about the autotrophs is incorrect?
(a) They synthesise carbohydrates from carbon dioxide and water in the presence of sunlight and chlorophyll.
(b) They store carbohydrates in the form of starch.
(c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight.
(d) They constitute the first trophic level in food chains.
Answer: (c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight.

Question. Which is the correct sequence of parts in human alimentary canal?
(a) Mouth \(\rightarrow\) stomach \(\rightarrow\) small intestine \(\rightarrow\) oesophagus \(\rightarrow\) large intestine
(b) Mouth \(\rightarrow\) oesophagus \(\rightarrow\) stomach \(\rightarrow\) large intestine \(\rightarrow\) small intestine
(c) Mouth \(\rightarrow\) stomach \(\rightarrow\) oesophagus \(\rightarrow\) small intestine \(\rightarrow\) large intestine
(d) Mouth \(\rightarrow\) oesophagus \(\rightarrow\) stomach \(\rightarrow\) small intestine \(\rightarrow\) large intestine
Answer: (d) Mouth \(\rightarrow\) oesophagus \(\rightarrow\) stomach \(\rightarrow\) small intestine \(\rightarrow\) large intestine

Question. What prevents backflow of blood inside the heart during contraction?
(a) Valves in heart
(b) Thick muscular walls of ventricles
(c) Thin walls of atria
(d) Inner lining of the heart
Answer: (a) Valves in heart

Question. Which of the following equations is the summary of photosynthesis?
(a) \( 6CO_2 + 12H_2O \rightarrow C_6H_{12}O_6 + 6O_2 + 6H_2O \)
(b) \( 6CO_2 + H_2O + \text{Sunlight} \rightarrow C_6H_{12}O_6 + O_2 + 6H_2O \)
(c) \( 6CO_2 + 12H_2O + \text{Chlorophyll} + \text{Sunlight} \rightarrow C_6H_{12}O_6 + 6O_2 + 6H_2O \)
(d) \( 6CO_2 + 12H_2O + \text{Chlorophyll} + \text{Sunlight} \rightarrow C_6H_{12}O_6 + 6CO_2 + 6H_2O \)
Answer: (c) \( 6CO_2 + 12H_2O + \text{Chlorophyll} + \text{Sunlight} \rightarrow C_6H_{12}O_6 + 6O_2 + 6H_2O \)

Question. Lack of oxygen in muscles often leads to cramps among cricketers. This results due to
(a) conversion of pyruvate to ethanol.
(b) conversion of pyruvate to glucose.
(c) non conversion of glucose to pyruvate.
(d) conversion of pyruvate to lactic acid.
Answer: (d) conversion of pyruvate to lactic acid.

Question. Name the following:
(a) The process in plants that links light energy with chemical energy.
(b) Organism that can prepare their own food.
(c) The cell organelle where photosynthesis occurs.
(d) Cells that surround a stomatal pore.
(e) Organisms that cannot prepare their own food.
(f) An enzyme secreted from gastric glands acts on proteins.
Answer: (a) Photosynthesis (b) Autotrophs (c) Chloroplasts (d) Guard cells (e) Heterotrophs (f) Pepsin

Question. “All plants give out oxygen during day and carbon dioxide during night”. Do you agree with this statement? Give reason.
Answer: Yes, respiration takes place throughout day and night but photosynthesis occurs only during the day. During daytime, plants give out oxygen which is a product of photosynthesis. Thus, during night when there is no photosynthesis, plants liberate carbon dioxide.

Question. Two green plants are kept separately in oxygen free containers. One in dark and other in continuous light which one will longer? Give reasons.
Answer: The plant which kept in continuous light will live longer because in light, the plant will be able to undergo photosynthesis and able to convert carbon dioxide into oxygen whereas the plant in dark cannot perform photosynthesis and lack of oxygen will kill the plant.

Question. Why do fishes die when taken out of water?
Answer: Fishes die when taken out of water because they cannot obtain gaseous oxygen. They breath through gills, which are richly supplied with blood capillaries and can readily absorb oxygen dissolved in water.

Question. Is ‘nutrition’ a necessity for an organism? Discuss.
Answer: Yes, ‘nutrition’ is a necessity for an organism because:
(i) It is required for the growth of new cells and repair of worn out cells.
(ii) It is required to develop resistance against various diseases.
(iii) It gives us energy for various metabolic activities of our body.

Question. What would happen if green plants disappear from earth?
Answer: If green plants disappear from earth, then the herbivores will die of starvation followed by carnivores and then decomposers.

Question. Leaves of a healthy potted plant were coated with vaseline will this plant remain healthy for long? Give reasons for your answer.
Answer: (a) The plant will die soon because layer of vaseline will prevent the exchange of gases for respiration. (b) It will also close the stomatal openings and plant won’t be able to get the necessary raw materials for photosynthesis.

Question. What are the adaptations of leaf for photosynthesis?
Answer: The adaptations of leaf for photosynthesis are as follows:
(i) Leaf has a large surface area to absorb maximum light.
(ii) Arrangement of leaves in order to absorb optimum amount of light.
(iii) The large number of veins provide mechanical strength and also take part in quick transport of substances to and from the mesophyll cells.
(iv) Leaf is the site of transpiration which cools the leaf surface for optimum photosynthesis.
(v) Leaf has numerous stomata for gaseous exchange.
(vi) Large number of chloroplasts are present on upper surface of leaves.

Question. Why do herbivores have longer, small intestine than carnivores?
Answer: Cellulose is difficult to digest and hence takes a longer time for complete digestion which is why herbivores need a comparatively longer small intestine. Meat is easy to digest and hence carnivores like tigers have a comparatively shorter small intestine.

Question. Why is small intestine in herbivores longer than in carnivores?
Answer: Herbivores eat grass and need a longer small intestine to allow complete digestion of cellulose. But carnivores cannot digest cellulose, and therefore they have a shorter intestine.

Question. What will happen if mucus is not secreted by the gastric glands?
Answer: If mucus is not secreted by the gastric glands, it will lead to corrosion of inner lining of stomach, causing excessive acidity, ulcers and extreme discomfort as mucus protects the inner lining of stomach from the action of hydrochloric acid and enzyme pepsin.