Class 7 Science: Life Processes in Animals MCQs (NCERT)
105 practice questions on Life Processes in Animals, a chapter in the NCERT Class 7 Science textbook, organised into 3 topics. Every question includes a written explanation. Pick a topic below, or try the samples first.
Air passes from the nose and throat down to the lungs through a tube called the
Agill slit
Bfood pipe
Cspiracle
Dwindpipe
Show answer and explanation
Correct answer: D - windpipe
The windpipe is the air passage that leads from the throat down into the lungs. The food pipe carries swallowed food to the stomach, while spiracles and gill slits are the breathing structures of insects and fish and are not found in human beings.
Q2
hard
Assertion (A): A person's breathing rate rises during heavy exercise. Reason (R): Working muscles need more oxygen so that more energy can be released from food.
ABoth A and R are true, and R is the correct explanation of A
BBoth A and R are true, but R is not the correct explanation of A
CA is true, but R is false
DA is false, but R is true
Show answer and explanation
Correct answer: A - Both A and R are true, and R is the correct explanation of A
Both statements are true and the reason explains the assertion. Muscles doing hard work need extra energy, that energy comes from food broken down with oxygen, and the quickest way to bring in more oxygen is to breathe faster and more deeply.
Q3
easy
Why should food be chewed well before it is swallowed?
Ait changes the food into water
Bit stops the stomach from making any strong juice, so the lining of the stomach does not get hurt
Cit is broken into small pieces and mixed with saliva, so digestion becomes easier
Dit makes salty or spicy food taste milder, so that it is pleasant to swallow
Show answer and explanation
Correct answer: C - it is broken into small pieces and mixed with saliva, so digestion becomes easier
Chewing breaks food into small bits and mixes saliva into them, so the digestive juices can act on a far larger surface and the work goes faster. Chewing does not change how salty a food is, the stomach makes its juice in any case, and food is never turned into water.
Q4
medium
Earthworms are often seen crawling on the ground after very heavy rain. The most likely reason is that
Awater fills the spaces in the soil, so the worms cannot get enough air there
Bthe rain washes every worm out of its burrow
Cthey come out to dry their skin completely in the air, since a dry skin works best
Dthey come out in order to drink the rain water
Show answer and explanation
Correct answer: A - water fills the spaces in the soil, so the worms cannot get enough air there
Rain water fills the air spaces between the soil particles, leaving too little air around the burrow, so the worms move up to the surface. They take in water through the skin and need not drink it, and a worm whose skin dried out could not breathe at all.
Q5
easy
In human beings, the air drawn in through the nose finally reaches the
Asmall intestine
Bstomach
Clungs
Dheart
Show answer and explanation
Correct answer: C - lungs
Air travels from the nose down the windpipe and into the lungs, where the exchange of gases takes place. Food and not air goes to the stomach and the intestine, and the heart pumps blood rather than taking in air.
Q6
medium
Why does a cow swallow grass quickly and chew it properly only later?
Achewing grass while standing would make it too tired to walk
Bit can crop a lot of grass quickly in the open field and chew the stored grass at rest
Cit has no teeth at all in its mouth to chew grass with
Dit is unable to swallow any food that has already been chewed, so it swallows grass whole first
Show answer and explanation
Correct answer: B - it can crop a lot of grass quickly in the open field and chew the stored grass at rest
A grazing animal is safest when it can gather food fast and then move away, so it swallows grass almost unchewed and chews the stored cud later while resting. A cow does have grinding teeth, and it swallows the chewed cud a second time, so the other options contradict what a cow is seen to do.
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