(a) What is chlorophyll ? What part does chlorophyll play in photosynthesis ?
(b) (i) Which simple food is prepared first in the process of photosynthesis ?
(ii) Name the food which gets stored in plant leaves.
(a) Chlorophyll is a green coloured pigment present in the leaves of plants. It helps in absorbing energy from sunlight during the process of photosynthesis.(b) (i) Glucose(ii) Starch.
(a) What criteria can be used to decide whether something is alive ?
(b) What is meant by life processes ? Name the basic life processes common to all living organisms which are essential for maintaining life.
(a) The criteria to decide whether something is alive is the movement.
(b) The basic functions performed by living organisms to maintain their life on this earth are called life processes. The basic life processes common to all living organisms are ? Nutrition and Respiration; Transport and Excretion; Control and Coordination; Growth; Movement and Reproduction.
(a) What are autotrophs ? Give one example of autotrophs.
(b) What are the conditions necessary for autotrophic nutrition ?
(a) Autotrophs are those organisms which can make their own food from carbon dioxide and water. Example: Green Plants.(b) The conditions necessary for autotrophic nutrition are sunlight, chlorophyll, carbon dioxide and water.
(a) What are heterotrophs ? Give one example of heterotrophs.
(b) What is the difference between autotrophic nutrition and heterotrophic nutrition ?
(a) Those organisms which cannot make their own food from inorganic substances like carbon dioxide and water, and depend on other organisms for their food are called heterotrophs. Example: All Animals.
It is that mode of nutrition in which an organism makes its own food from the simple inorganic materials like carbon dioxide and water present in the surroundings (with the help of sunlight energy) Example: Green Plants
It is that mode of nutrition in which an organism cannot make its own food from simple inorganic materials like carbon dioxide and water, and depends on other organisms for its food.Example: Animals.
(a) Define a nutrient. Name four important nutrients present in our food.
(b) What are the various types of heterotrophic nutrition ?
(a) A nutrient can be defined as a substance which an organism obtains from its surroundings and uses it as a source of energy or for the biosynthesis of its body constituents (like tissues and organs). The four important nutrients present in our food are: carbohydrates, fats, proteins and mineral salts.
(b) The various types of Heterotrophic nutrition are:
(i) Saprotrophic nutrition.
(ii) Parasitic nutrition.
(iii) Holozoic nutrition.
(a) Photosynthesis converts energy X into energy Y. What are X and Y ?
(b) State the various steps involved in the process of photosynthesis.
(a) X is sunlight energy and Y is chemical energy.
(b) The photosynthesis takes place in the following three steps;
(i) Absorption of sunlight energy by chlorophyll.
(ii) Conversion of light energy into chemical energy and splitting of water into hydrogen and oxygen by light energy.
(iii) Reduction of carbon dioxide by hydrogen to form carbohydrates like glucose by utilising the chemical energy
(a) How do plants obtain food ?
(b) Why do plants need nitrogen ? How do plants obtain nitrogen ?
(a) Plants obtain food by a process called photosynthesis.
(b) Plants need nitrogen to make proteins and other compounds. They take up nitrogen from the soil in the form of inorganic salts called nitrates (or nitrites), or in the form of organic compounds which are produced by bacteria from the atmospheric nitrogen.
Define (i) saprophytic nutrition (ii) parasitic nutrition, and (iii) holozoic nutrition. Give one example of each type.
(i) Saprophytic nutrition: It is that nutrition in which an organism obtains its food from dead organic matter of dead plants, dead animals and rotten bread. Example: Fungi and many bacteria obtain food by saprophytic nutrition.
(ii) Parasitic nutrition: It is that nutrition in which an organism derives its food from the body of another living organism (called its host) without killing it.Example: Plasmodium and round worms obtain food by parasitic nutrition.
(iii) Holozoic nutrition: It is that nutrition in which an organism takes the complex organic food materials into its body by the process of ingestion; the ingested food is digested and then absorbed into the body cells of the organism.Example: Human beings obtain food by holozoic nutrition
Define (2) saprophyte, and (22) parasite. Name two saprophytes and two parasites.
(a) Saprophyte – Saprophytes are the organisms which obtain their food from dead plants (like rotten leaves), dead and decaying animal bodies, and other decaying organic matter (like rotten bread).Example: Fungi and some bacteria.
(b) Parasite: A parasite is an organism (plant or animal) which feeds on another living organism called its host.Example: Plasmodium and round worm.
(a) How does carbon dioxide from the air enter the leaves of a plant to be used in photosynthesis ?
(b) How does water from the soil reach the leaves of a plant to be used in photosynthesis ?
(a) The carbon dioxide gas enters the leaves of the plants through the stomata present on their surface.
(b) The water required by the plants for photosynthesis is absorbed by the roots of the plants from the soil through the process of osmosis. The absorbed water is then transported upward through the xylem vessels to the leaves where it reaches the photosynthetic cells and utilized in photosynthesis.
What substances are contained in gastric juice ? What are their functions ?
The gastric juice contains three substances; hydrochloric acid, the enzyme pepsin and mucus. Functions: (a) Hydrochloric acid: It makes the medium of gastric juice acidic so that the enzyme pepsin can digest the proteins properly and also kills any bacteria that might have entered the stomach with food.
(b) Pepsin: The enzyme pepsin digests the proteins present in the food and converts them into smaller molecules.
(c) Mucus: The mucus helps to protect the stomach wall from its own secretions of hydrochloric acid.
What substances are contained in pancreatic juice ? What are their functions ?
Pancreatic juice contains digestive enzymes ? Pancreatic Amylase, trypsin and lipase. Functions:
(a) Pancreatic amylase: The enzyme amylase breaks down the starch.
(b) Trypsin: trypsin digests the proteins.
(c) Lipase: Lipase breaks down the emulsified fats.
(a) What is the role of hydrochloric acid in our stomach ?
(b) What is the function of enzymes in the human digestive system ?
(a) Hydrochloric acid: It makes the medium of gastric juice acidic so that the enzyme pepsin can digest the proteins properly and also kills any bacteria that might have entered the stomach with food.
(b) Enzymes help in the breaking down of complex organic food materials into simpler forms.
(a) Which part of the body secretes bile ? Where is bile stored ? What is the function of bile ?
(b) What is trypsin ? What is its function ?
(a) Liver secretes bile which gets stored in the gall bladder. Bile performs two functions:
(i) Makes the acidic food coming from the stomach alkaline so that the pancreatic enzymes can act on it.
(ii) Bile salts breaks the fats present in the food into small globules making it easy for the enzymes to act and digest them.
(b) Trypsin: It is a pancreatic enzyme present in the pancreatic juice. Its function is to digest the proteins.
What are the functions of liver and pancreas in the human digestive system ?
Liver secretes bile which helps in the emulsification of fats. Pancreas secretes pancreatic juice which emulsifies starch, proteins and fats.
Match the organisms given in column I with the processes given in column II :
(a) Holozic nutrition
(b) Autotrophic nutrition
(c) Parasitic nutrition
(iv) Green Plant
(d) Saprophytic nutrition
(i) – (c)
(ii) – (a)
(iii) – (d)
(iv) – (b)
Name the following :
(a) The process in plants which converts light energy into chemical energy.
(b) Organisms that cannot prepare their own food.
(c) Organisms that can prepare their own food.
(d) The cell organelle where photosynthesis occurs.
(e) The cells which surround a stomatal pore.
(f) An enzyme secreted by gastric glands in stomach which acts on proteins.
(e) Guard cells.
Match the terms in column I with those in column II :
(b) Gastric Glands
(i) – (c)
(ii) – (d)
(iii) – (a)
(iv) – (b)