Fill in the blanks:
(a) The main steps of nutrition in humans are __________, __________, __________, _________ and __________.
(b) The largest gland in the human body is __________.
(c) The stomach releases hydrochloric acid and ___________ juices which act on food.
(d) The inner wall of the small intestine has many finger-like outgrowths called _________.
(e) Amoeba digests its food in the ____________ .
a) ingestion, digestion, absorption, assimilation, egestion
These are the basic steps of holozoic nutrition.
1. Ingestion: Ingestion involves the consumption of food by an organism. Animals are variously adapted for ingestion of food of specific types, that intakes through the mouth into the gastrointestinal tract (GI); by eating or drinking processes. In single-celled organisms ingestion takes place by absorbing a substance through the cell membrane or through the surface of the skin.
2. Digestion: Digestion involves the breakdown of large complex organic food molecules (carbohydrates, proteins, lipids, nucleic acid etc.) into the simpler, smaller or soluble molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substance are absorbed by the small intestine into the blood stream.
3. Absorption: Absorption involves passing of digested food components through the wall of small intestine into the blood of lymph. These absorbed food molecules circulated to different cells of the body where they are being absorbed.
4. Assimilation: Assimilation involves the movement of digested food molecules into the different cells of the body where they are used. For example: glucose is used in respiration to provide energy to do the processes; and amino acids are used to build new proteins.
5. Egestion: Egestion involves the removal or elimination of undigested food materials from the alimentary canal as faeces.
On reaching the end of the small intestine the digested food products with the minerals and vitamins that are useful to the body, this should have been removed from the watery contents. These materials are then passed on to the large intestine for the forward processes.
(b) liver
Liver is the largest gland which is located in the upper right side of the abdominal cavity. The liver consists of two lobes: the right and the left lobe. The liver is an essential organ weighing body 1.6 kg that has many functions in the body, including making proteins and blood clotting, making of triglycerides and cholesterol, synthesis of glycogen and bile production.
(c) pepsinogen, prorennin etc.
Contraction and the expansion of muscles of the wall of the stomach brings about churning movement which helps in the mixing of food with the gastric juices which is a mixture of HCL, pepsinogen, prorennin, lipase and mucus etc.
(d) villi
Villi are small finger-like numerous microscopic projections found inside the inner walls of the small intestine. Villi absorb nutrients from the food we eat and then shuttle those nutrients into your bloodstream so that they can travel where they’re needed.
(e) food vacuole
A vacuole is a membrane-bound organelle and are kind of vesicle. Vacuoles are closed sacs, made of membranes with inorganic or organic molecules inside such as enzymes. They have irregular shape or size like the cell can change them as needed. They are present in eukaryotic cells and do many things.
Popular Questions of Class 7 Science
- Q:-
Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food - Q:-
Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down Across
(D) 1 : Thorough washing (A) 1 : Keeps warm
2 : Animal fibre 2 : Its leaves are eaten by silkworms
3 : Long thread like structure 3 : Hatches from egg of moth
- Q:-
Sketch the cross section of soil and label the various layers.
- Q:-
Here is a crossword puzzle: Good luck!
Across
3. Liquid waste products
4. Solid waste extracted in sewage treatment
6. A word related to hygiene
8. Waste matter discharged from human bodyDown
1. Used water
2. A pipe carrying sewage
5. Micro-organisms which causes cholera
7. A chemical to disinfect water - Q:-
Take three test-tubes. Fill æth of each with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2?
- Q:-
Sketch the reproductive parts of a flower.
- Q:-
Solve the following crossword puzzle with the clues given:
Across
2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.Down
1. In desert soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil. - Q:-
Describe how crystals of copper sulphate are prepared.
- Q:-
Match the items in Column I with those in Column II:
Column I Column II
(i) A home for living organisms (a) Large particles
(ii) Upper layer of the soil (b) All kinds of soil
(iii) Sandy soil (c) Dark in colour
(iv) Middle layer of the soil (d) Small particles and packed tight (v) Clayey soil (e) Lesser amount of humus - Q:-
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
Recently Viewed Questions of Class 7 Science
- Q:-
Salma takes 15 minutes from her house to reach her school on a bicycle. If the bicycle has a speed of 2 m/s, calculate the distance between her house and the school.
- Q:-
Fill in the blanks:
(i) The average weather taken over a long time is called ___________. (ii) A place receives very little rainfall and the temperature is high throughout the year, the climate of that place will be ___________ and ___________ .
(iii) The two regions of the earth with extreme climatic conditions are ___________ and __________. - Q:-
Can we survive only on raw, leafy vegetables/grass? Discuss.
- Q:-
Make sketches of the two stages in the life history of the silk moth which are directly related to the production of silk.
- Q:-
Explain the relationship between sanitation and disease.
- Q:-
Mark ‘T’ if the statement is true and ‘F’ if it is false:
(i) Nitric acid turn red litmus blue. (T/F)
(ii) Sodium hydroxide turns blue litmus red. (T/F)
(iii) Sodium hydroxide and hydrochloric acid neutralise each other and form salt and water. (T/F)
(iv) Indicator is a substance which shows different colours in acidic and basic solutions. (T/F)
(v) Tooth decay is caused by the presence of a base. (T/F) - Q:-
Describe the steps involved in getting clarified water from wastewater.
- Q:-
How would you test the presence of starch in leaves?
- Q:-
Explain how painting of an iron gate prevents it from rusting.
- Q:-
An electrician is carrying out some repairs in your house. He wants to replace a fuse by a piece of wire. Would you agree? Give reasons for your response.
- NCERT Chapter