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Karnataka State Syllabus Class 8 Science Chapter 19 Nutrition and Respiration
KSEEB Class 8 Science Nutrition and Respiration Textbook Exercise Questions and Answers
I. Four alternatives are given to each of the following incomplete statements/questions. Choose the right answer.
Question 1.
The process of obtaining food and utilizing it in the body is …………………………
(a) respiration
(b) nutrition
(c) excretion
(d) reproduction
Answer:
(b) nutrition
Question 2.
One of these is a product of photosynthesis …………………………
(a) starch
(b) glucose
(c) maltose
(d) sucrose
Answer:
(a) starch
Question 3.
Insectivorous plants commonly grow in areas where soil is deficient in …………………………
(a) carbon
(b) nitrogen
(c) potassium
(d) phosphorus
Answer:
(b) nitrogen
Question 4.
A person applies hydrogen peroxide on his wound. This is to kill …………………………
(a) anaerobic bacteria
(b) aerobic bacteria
(c) fungi
(d) protozoa
Answer:
(c) fungi
Question 5.
Amylase converts starch to …………………………
(a) glucose
(b) sucrose
(c) lactose
(d) maltose
Answer:
(d) maltose
II. Answer the following:
Question 1.
What are life processes?
Answer:
The processes Such as respiration, nutrition, growth movement response to Stimuli excretion and reproduction called as life processes.
Question 2.
Explain the method of testing a leaf for starch.
Answer:
Collect a few leaves from a plant. Put them it in water for some time and then take out. Then dip them in a spirit and then in iodine solution. Observe that the leaf turns blue-black, showing the presence of starch.
Question 3.
Explain an experiment to demonstrate that oxygen is released during photosynthesis.
Beaker kept In cupboard – Beaker kept in sun
Answer:
Take two beakers filled with water. Add a few crystals of sodium bicarbonate to both. Place Hydriila plants in both beakers kept in sun and invert large funnels over them. Take two test tubes.
Place small pieces of steel wool into the bottom and fill the test tubes with water and invert them over the narrow ends of each, of the funnel. Place one of the beakers in a bright sunny area and the other in a dark cupboard for about 48 hours.
Take the test tube. Test the gas collected in the test by introducing splinters. The splinter burns brightly in the gas collected in the test tube which is kept outside, but not in the one kept in the cupboard.
Also, the steelwool in the test tube kept in sun turns brown due to oxidation. From this experiment, we can show that the gas released during photosynthesis is oxygen.
Question 4.
Differentiate between the two phases of photosynthesis.
Answer:
Light-dependent reaction
- Takes place in the presence of sunlight
- Takes place in the grana region of the chloroplast
- During this reaction, water is decomposed into hydroxyl and hydrogen ions by the help of light energy
- Oxygen is given out in this reaction
- light energy is converted into chemical energy and stored in the form of ATP
- known as photochemical reaction Light independent reaction
- takes place in the without using sunlight
- takes place in the stroma region of the chloroplast.
- in this reaction, C02 is reduced to starch utilizing the energy released during the light-dependent reaction.
- known as Calvin cycle
Question 5.
What are parasites? Give two examples.
Answer:
The organisms which obtain food from other organisms are called parasites. There are two types namely, semi parasites, and total parasites.
Semiparasite example:- Viscum
Total parasite example:- Cuscuta, intestinal worms like Tapeworm, roundworm, etc.
Question 6.
Amoeba cannot digest fats, why?
Answer:
Amoeba has no enzyme to digest fats, like lipase to convert fats into simple fats. Therefore amoeba cannot digest fats.
Question 7.
Explain the respiration in the cockroach.
Answer:
The tracheal system of cockroach includes stigmata, Trachea, and Tracheoles, stigmata are the respiratory openings in the cockroach. They are present on the lateral sides of the body. Trachea and Tracheoles Carry Oxygen From the diffused air to all parts of the body, cells take in oxygen and give out carbon dioxide to the tracheal Haemo lymph is involved in the gaseous exchange, The carbon dioxide has differed out through the spiracle openings.
Question 8.
Explain respiration in human beings.
Answer:
Air enters into the nasal cavity through the nostrils, Dust particles present in the air are prevented from entering the lungs. Air passes to the pharynx and then into the trachea, It has ‘C shaped rings which prevent it. From collapsing, Trachea is divided into bronchi and into bronchioles and a number of alveoli Blood circulating around the alveoli gives out CO2. This oxygenated bolls reaches the cells and gives oxygen to the cells and is used for oxidizing glucose, co, formed as a product is carried by the blood to the alveoli and exhaled in the same pathway.
Question 9.
Draw a diagram of the human digestive system and label the parts.
Answer:
KSEEB Class 8 Science Nutrition and Respiration Additional Questions and Answers
I. Answer the following:
Question 1.
What are autotrophs?
Answer:
The organisms which prepare their own food are called as autotrophs. Example: Green plants.
Question 2.
What is photosynthesis?
Answer:
The process by which green plants manufacture organic compounds by using CO2 and H2O in the presence of sunlight and chlorophyll is called photosynthesis
Question 3.
How did earth’s atmosphere become friendly to the organisms?
Answer:
At the time of origin of life, the earth had more of carbon dioxide. Gradually, algae and primitive plants started appearing. These algae and the other lower plants utilized this carbon dioxide to prepare food, and in turn, gave back oxygen to the atmosphere. Thus, the level of oxygen increased in Earth’s atmosphere which is also a reason for new kinds of life forms to emerge on earth.
Question 4.
Write the equation for the photochemical reaction.
Answer:
Question 5.
Draw a neat diagram to show a section of the leaf.
Answer:
Question 6.
What are insectivorous plants?
Answer:
Photosynthetic plants which grow in soil, which is poor in nitrogen content, try to obtain nitrogen by trapping and digesting insects and are called insectivorous plants.
Example: Drosera, Nepenthes
Question 7.
What are epiphytes?
Answer:
The photosynthetic plants which take shelter in the host tree are called epiphytes, example: orchids
Question 8.
What are saprophytes?
Answer:
The organisms which obtain food from dead and decaying organic matter by decomposing the same are called as saprophytes. Example: bacteria and fungi
Question 9.
Give examples for fungi.
Answer:
Bread mould and Agaricus, yeast etc.
Question 10.
How do fungi derive nutrition?
Answer:
Fungi absorb food from decaying organic materials with the help of structures called hyphe.
Question 11.
How do orchids absorb water?
Answer:
Orchids can absorb moisture from the atmosphere through the special aerial roots containing sponge valamen tissue.
Question 12.
What is the role of E- Coli bacteria in humans?
Answer:
E – Coli bacteria present in the intestine of man provide the vital
B – Complex vitamins.
Question 13.
What is meant by symbiosis?
Answer:
The mode of nutrition in which two organisms live together and are mutually benefitted is called mutualism or symbiosis.
Example: Lichens, are formed of alga and fungus. Fungus absorbs water which is utilized by alga for photosynthesis and food prepared by alga is utilized by fungus.
Question 14.
Mention the steps involved in Holozoic nutrition?
Answer:
The holozoic nutrition involves five steps namely ingestion, digestion, absorption, assimilation and egestion.
Question 15.
Define the following terms.
Answer:
- Ingestion: Process of taking the food is called ingestion.
- Digestion: Conversion of complex larger molecules into simple smaller molecules by the action of enzymes for easy
- absorption is called digestion. Absorption: Taking in of soluble digested nutrients into the blood is called absorption.
- Assimilation: The process of converting the digested food into protoplasm, ie, storing or utilizing in the cells is called assimilation.
- Egestion: Elimination of undigested food from the animal body is called egestion.
Question 16.
What are antennae and mention their function?
Answer:
The pair of feelers in the head region of cockroach is called antennae, they sens the food and push it into the mouth.
Question 17.
Mention the parts of the alimentary canal of humans.
Answer:
The alimentary canal includes the mouth, pharynx, oesophagus stomach, small intestine, large intestine, and anus.
Question 18.
What happens to food in the mouth?
Answer:
The ingested food is subjected to mechanical break down in the mouth. Food is chewed and churned with the help of teeth and tongue. Saliva makes food into a soft paste called a bolus. The enzyme amylase present in saliva converts starch into maltose.
Question 19.
Mention the acid present in the gastric juice. Mention its function.
Answer:
The gastric juice contains hydrochloric acid. It kills the microbes that enter the stomach through food and water.
Question 20.
Mention the enzymes present in gastric juice and mention their function.
Answer:
- Pepsin – Coverts proteins into polypeptides.
- Rennin – converts the soluble milk proteins into insoluble curds.
Question 21.
Name the juice produced by the liver and where is it stored?
Answer:
Bile juice is produced by the liver and it is stored in the gall bladder. Bile juice emulsifies fats.
Question 22.
Name the enzymes present in the pancreatic juice.
Answer:
Pancreatic juice contains enzymes.
- Amylase – converts starch into maltose
- Lipase – converts complex fats into simple fats
- Protease – breaks polypeptides into smaller peptides
Question 23.
Name the enzymes present in the intestinal juice.
Answer:
- Maltase – converts maltose into glucose.
- Sucrase – converts sucrose into glucose
- Lactase – converts lactose into glucose
- Peptidase – converts peptides into amino acids.
- Lipase – converts fats into fatty acids and glycerol.
Question 24.
What are villi?
Answer:
The finger-like projections of the small intestine which absorb the digested food are called villi.
Question 25.
What is respiration?
Answer:
Respiration is a process by which energy is liberated by oxidation of food.
Question 26.
Differentiate between aerobic and anaerobic respiration.
Answer:
Aerobic respiration:
- oxygen is used to break down organic compounds into CO2, and H2O
- a large amount of energy is liberated
- It occurs in higher forms of organisms.
- C6 H12 O6 + 6O2 → 6 CO2 + 6 H2O + Energy( 673 kcal)
Anaerobic respiration;
- Organic compounds are broken in the absence of oxygen, producing alcohol and C02
- Only a small amount of energy is liberated
- It occurs in lower forms of organisms
- C6 H12 O6 → 2 C2 H5 OH + 2 CO2 + Energy(56 k cal)