NCERT Solutions for Class 10th Science
Chapter 6 – LIFE PROCESSES
(Complete Downloadable Chapter Solution PDF file is at the bottom of the page)
Q.1 Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
Ans Multicellular organisms like humans have complex body design in which they have specialised cells and tissues for performing various activities such as intake of food and oxygen. Unlike single-celled organisms, all these cells of multicellular organisms may not be in direct contact with the surrounding environment. Thus, simple diffusion will not meet the requirements of all the cells.
Q.2 What criteria do we use to decide whether something is alive?
Ans Movements of various types such as visible to the naked eye like growing, breathing etc. and invisible to the naked eye like molecular movements can be taken as an indication that something is alive.
Q.3 What are outside raw materials used for by an organism?
Ans An organism uses mainly food and oxygen as outside raw materials for following purposes.
1) To generate or derive the energy for performing various activities.
2) To perform maintenance processes i.e. building up new tissues and repair of old tissues.
Q.4 What processes would you consider essential for maintaining life?
Ans Life processes such as nutrition, respiration, excretion, transportation (of materials within the body) etc. are essential for maintaining life.
Q.5 What are the differences between autotrophic nutrition and heterotrophic nutrition?
Q.6 Where do plants get each of the raw materials required for photosynthesis?
Q.7 What is the role of the acid in our stomach?
Q.8 What is the function of digestive enzymes?
Q.9 How is the small intestine designed to absorb digested food?
Ans The inner lining of the small intestine has numerous finger-like projections called villi which increase the surface area for absorption. The villi are richly supplied with blood vessels which take the absorbed food to each and every cell of the body.
Q.10 What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Q.11 What are the different ways in which glucose is oxidised to provide energy in various organisms?
Q.12 How is oxygen and carbon dioxide transported in human beings?
Q.13 How are the lungs designed in human beings to maximise the area for exchange of gases?
Ans Lungs have a million of alveoli (balloon like structures), where the exchange of gases takes place. During inhalation, we lift our ribs and flatten our diaphragm, because of which, air is sucked into the lungs and fills the expanded alveoli. These expanded alveoli provide a large surface area for the exchange of gases. Further, the walls of alveoli have an extensive network of blood capillaries which makes the process of exchange of gases more efficient.
Q.14 What are the components of the transport system in human beings? What are the functions of these components?
Ans Components of the transport system in human beings – Heart, blood & blood vessels.
Heart – A pumping organ which pumps the oxygen rich blood to all parts of the body and the deoxygenated blood coming from the body to the lungs for oxygenation.
Blood – Blood consists of a fluid medium called plasma which transports food, CO2 and nitrogenous wastes in dissolved form. Oxygen is carried by the red blood cells. It also transports many other substances like salts etc.
Blood Vessels – Arteries carry blood (oxygenated) from heart to various parts of body and veins carry blood (deoxygenated) from different parts of the body to the heart. Capillaries help in exchange of material between blood and surrounding cells.
Q.15 Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
Q.16 What are the components of the transport system in highly organised plants?
Q.17 How are water and minerals transported in plants?
Q.18 How is food transported in plants?
Q.19 Describe the structure and functioning of nephrons.
Q.20 What are the methods used by plants to get rid of excretory products?
Q.21 How is the amount of urine produced regulated?
EXERCISES
Q.1 The kidneys in human beings are a part of the system for
(a) nutrition.
(b) respiration.
(c) excretion.
(d) transportation.
Ans (c) excretion
Q.2 The xylem in plants are responsible for
(a) transport of water.
(b) transport of food.
(c) transport of amino acids.
(d) transport of oxygen.
Ans (a) transport of water.
In the plants, xylem moves water and minerals obtained from the soil through roots to all other parts of the plant.
Q.3 The autotrophic mode of nutrition requires
(a) carbon dioxide and water.
(b) chlorophyll.
(c) sunlight.
(d) all of the above.
Ans (d) all of the above.
Q.4 The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
(a) cytoplasm.
(b) mitochondria.
(c) chloroplast.
(d) nucleus.
Ans (b) mitochondria
Q.5 How are fats digested in our bodies? Where does this process take place?
Q.6 What is the role of saliva in the digestion of food?
Q.7 What are the necessary conditions for autotrophic nutrition and what are its byproducts?
Q.8 What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.
Q.9 How are the alveoli designed to maximise the exchange of gases?
Ans Alveoli are the balloon like structures in the lungs into which smaller tubes of air passage terminate.Lungs have millions of alveoli, which provide surface for the exchange of gases. During inhalation, air is sucked into the lungs and fills the expanded alveoli. These expanded alveoli provide a large surface area for the exchange of gases (If the alveolar surface were spread out, it would cover about 80m2). Further, the walls of alveoli have an extensive network of blood capillaries which makes the process of exchange of gases more efficient.
Q.10 What would be the consequences of a deficiency of haemoglobin in our bodies?
Q.11 Describe double circulation in human beings. Why is it necessary?
Ans Double circulation in human beings means the blood goes through their heart twice during each cycle of passage through the body. Human heart has four chambers named left atrium, left ventricle, right atrium and right ventricle. Deoxygenated blood
Q.12 What are the differences between the transport of materials in xylem and phloem?
Q.13 Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.