Question bank
LIFE PROCESSES
Q- What criteria do we use to decide whether something is alive?
If an organism shows the following characteristics, it means it is alive:
1. It is made up of cell /cells which has / have protoplasm.
2. It shows movement and locomotion.
3. It requires food for performing life activities.
4. It respires and utilizes the inhaled oxygen for oxidation of food.
5. It has the ability to receive the stimuli and gives appropriate responses.
6. It shows growth and development. ‘
7. It expels out metabolic wastes.
Q- What are outside raw materials used by an organism?
The important raw materials used by an organism are (i) oxygen for respiration and release of chemical energy, i.e., ATP, (ii) raw materials for nutrition for obtaining energy.
Q- What processes would you consider essential for maintaining life?
The processes essential for maintaining life are -- nutrition, respiration, transportation, excretion, control and coordination, movement and locomotion.
Q- What are the necessary conditions for autotrophic nutrition and what are its by-products?
Autotrophic nutrition (photosynthesis) occurs in the presence of sunlight and chlorophyll, and raw materials required for it are carbon dioxide (CO2) and water H2O.
Q- Why is diffusion insufficient to meet oxygen requirement of multicellular organisms humans?
In multicellular organisms like human beings only the cells of skin (surface layer) are exposed to surrounding environment. The rest of body cells of internal organs; are not in direct contact with the surrounding environment. Hence, exchange of gases by diffusion may not be possible in these cells. Thus, multicellular
organisms require specialized organs for breathing, exchange of gases and transport of gases to meet the oxygen requirement.
Q- Where do plants get each of the raw materials required for Photosynthesis?
The raw materials for photosynthesis are water and carbon dioxide. Plants get water from soil and carbon dioxide from atmosphere. Green Plants have chlorophyll in their chloroplasts and they receive solar energy from sun.
Q- Write the chemical equation involved in the process of photosynthesis?
The chemical equation involved in photosynthesis is-
6CO2 + 12H2O ⇢ C6H12O6 + 6O2 + 6H2O in presence of sunlight and chlorophyll.
Q- What is the role of saliva in the digestion of food?
Saliva performs the following functions:
(a) Moistens and softens the food.
(b) It contains enzyme salivary amylase which converts complex carbohydrates (starch) into simpler carbohydrates (maltose).
Q- What is the role of hydrochloric acid in our stomach?
Gastric HCl performs the following functions:
1. Provides acidic medium which is essential for the action of gastric enzyme pepsin.
2. It kills bacteria present in the food.
Q- How are fats digested in our bodies? Where does this process take place?
Fats are first acted upon by bile juice in duodenum (part of small intestine). They are then emulsified by bile juice. They are now acted upon by pancreatic lipase. Left over fat is converted into fatty acid by intestinal juice.
Fatty acid are absorbed by villi of small intestine. Thus, digestion of fat takes place in small intestine.
Q-What are the functions of digestive enzymes? ,‘
Digestive enzymes are secreted by digestive glands. They help in breaking down the complex food into simple absorbable form. Digestive enzymes finally convert Proteins into amino-acids, Complex carbohydrates into glucose and Fats into fatty acids and glycerol (simple carbohydrates).
Q- How is small intestine designed to absorb digested food?
Small intestine is extremely long. Its lining is very thin leading to rapid diffusion of substances. The surface area of intestine is greatly increased due to the presence of finger like projections called villi. Villi are highly supplied with blood capillaries and lymph capillaries.
Q- Who has longer small intestine — tiger or cow?
Cow has longer small intestine. The length of the small intestine differs in various animals depending on the food they eat. Herbivores (cow, goat, rabbit, etc) eating grass need a longer small intestine to allow the cellulose to be digested. Meat is easier to digest, hence carnivores like tiger, lion, etc have a shorter small intestine.
Q Why there is a controversy about whether virus are truely alive or not ?
Viruses do not show any visible or molecular movement in them until. they infect some cell. So, there is controversy whether they are alive or not.
Q Why are molecular movements needed for life ?
Molecular movements are required to provide various essential molecules throughout the body of an organism for repairing and maintaining their structure.
Q Why are life processes needed?
Life processes are needed to maintain functions of living organisms.
Q Which processes are called life processes ?
The processes which together perform the maintenance job in living organisms are called life processes.
Q Name the life processes needed to maintain life.
Life processes are (i) Nutrition (ii) Respiration (iii) Transportation (iv) Excretion
Q What exactly do life processes need to do ?
The life processes need to do :
(i) to provide food that provides energy and material required to sustain life. The process is called nutrition.
(ii) Respiration to supply oxygen to break down food (especially glucose) in the cells of organisms to release energy.
(iii) Transportation process for carrying food and oxygen from one place to another in the body. Also to transport wastes from body cells to excretory tissues.
(iv) Excretion process that removes the by-products produced during other life processes and carried to excretory tissues.
Q What are the raw materials for photosynthesis?
(CO2), water, sunlight, chlorophyll,
Q What is the Primary source of energy for all living beings ?
Sun.
Q Are their organisms that do not require water for photosynthesis?
The green sulphur bacteria use H2S (Hydrogen sulphide) instead of water.
Q What holozoic nutrition?
Feeding on solid food is known as holozoic nutrition.
Q What are enzymes ?
Enzymes are proteins which act as bio-catalysts and catalyse bio-chemical reactions.
Q Name the largest gland of the body?
Liver, which does not secrete any digestive enzyme.
Q Give two names of plant parasite.
Ann. Cuscuta and Loranthus.
Q Give two examples of animal parasites.
Astana and Tapeworm/Plasmodium.
Q Give two examples of Saprophytes.
Rhizopus and mushroom
Q. Differentiate between autotroph and heterotroph.
Autotrophs
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Heterotrophs
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1. They can make food from raw materials in presence of Sunlight.
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1. They cannot make their own food.
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2. They take in simple inorganic substances and change it into complex organic food
e.g all green plants.
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2 they take in complex food and break it into simple food.
e.g all animals and fungi and non green plants.
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Q. List the events that occur during photosynthesis.
Ans. During photosynthesis the following events occurs :
(i) Absorption of light energy by the chlorophyll pigment.
(ii) Conversion of light energy into chemical energy.
(iii) Splitting of water molecules into hydrogen and oxygen,
(iv) Reduction of carbon dioxide into carbohydrates.
Q. Do all events during photosynthesis take place one after the other immediately ? Give an example.
Ans. Not necessarily. For example, desert plants take up carbon dioxide at night and prepare an intermediate compound. This intermediate compound is acted upon by the energy absorbed during the day by the chlorophyll.
Q. Explain the structure of stomata and function of guard cells.
The outermost layer of cells i.e usually the epidermis is not continuous at some places e.g. on the surface of leaves or green herbaceous stems. The epidermis of the young shoot and leaves contains numerous minute pores called stomata. Each stomatal opening is surrounded by two semilunar cells known as the guard cells.
The term ‘stoma’ (plural-stomata) is applied to the stomatal opening plus the guard cells. The guard cells are living and contain chloroplasts. Their inner walls (wall towards opening) are thicker and outer walls thinner.
Function of Guard cells- The guard cells regulate the opening and closing of the stomatal pore. The guard cells swell when water flows into them causing the stomatal pore to open. Because inflow of water in guard cells causes the stretching and bulging of outer thin walls in converse shape. This drags thick walls apart leading to opening of the pore. When there is outflow of water from guard cells, the outer thin walls come to their original position resulting in closure of stomatal pore.
Q Write major functions of stomata present in the epldermis.
Major Functions of Stomata :
(i) Stomata are essential for exchange of gases between the plant and the atmosphere-oxygen and carbon dioxide.
(ii) Normally, plants eliminate excessive water in the form of vapour through stomatal openings. The process is called transpiration.
(iii) When there is shortage of water, stomatal openings get closed. Thus, reduce water lose. Stomatal openings also close down during night. Thus, stomata regulate water lose from plants i.e they regulate transpiration.
Q. Name the element that is essential in synthesis of proteins other than hydrogen and oxygen. How do plants obtain this element ?
(i) Nitrogen. .
(ii) Nitrogen is obtained by plants to take up it in the form of inorganic nitrates or nitrites. It may be taken up by plants as organic compounds which have been prepared by nitrogen fixing bacteria from atmosphere.
Q Write three modes of heterotrophic nutrition. Also give their examples.
The three modes of heterotrophic nutrition are:
(i) To break down of food material outside the body and then absorb it, For example, bread moulds, yeasts and mushroom.
(ii) To take in whole material and break it down in side the body. For example animals eating grass, fruits, insects, fish etc.
(iii) To derive nutrition from other plants or animals without killing them. For example, cuscuta (amar-bel), orchids, leeches, tape-worms etc,
Q. Animals depend on plants for food. Justify the above statement.
Plants have a property to fix solar energy into chemical energy by the process called photosynthesis. The chemical energy is locked in the food molecules which are taken up by the animals. This food is oxidised by the oxygen taken in from the atmosphere, also released by the plants, to give energy to the animals to do work and to grow. Thus heterotrophic organisms such as animals are dependant on plants, directly or indirectly.
Q. How does nutrition takes place in amoeba?
Engulflng of Food. Amoeba obtains its food by phagocytosis. Amoeba engulf its food by by forming pseudopodia. Two pseudopodia starts growing from opposite sides of food particles from amoeba.they completely encircles the food and their tips touch each other. The membrane of both the pseudopodia dissolves at the point of touching and the food is encaptured into the amoeba in food vacuole.
Digestion of food Inside food vacuole, complex substances are broken down into simpler ones. the digested simpler food is absorbed into food vacoule by cytoplasm.
Q How does nutrition takes place in paramaecium?
Paramaecium iss unicellular organism which has a definite shape (slipper-like).
Paramecium takes in food at a specific point (through oral groove to mouth to gullet). Food such as bacteria or very small organisms are move to the specific spot (ingestion point) by the movement of cilia which are present on all over the single-celled body.
From the gullet a food vacuole is formed which start circulating in the endoplasm. During circulation food is digested by enzymes. The digested food diffuses into the cytoplasm and undigested food is thrown out through anal pore.
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