This MCQ module is based on: Life Processes in Animals
TOPIC 34 OF 46
Life Processes in Animals
🎓 Class 7
Science
CBSE
Theory
Ch 9 — Life Processes in Animals
⏱ ~8 min
🌐 Language: [gtranslate]
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Chapter 9 Summary
All animals must eat and breathe to stay alive. Nutrition in animals follows five steps: ingestion, digestion, absorption, assimilation and egestion. In humans, food travels through the alimentary canal from mouth to anus, with the help of saliva, gastric juice, bile and pancreatic juice. The shape of an animal's teeth matches its food — chisel-like incisors and flat molars in herbivores, sharp canines in carnivores, and a mix in omnivores like us. Ruminants chew their cud after re-bringing it up to the mouth, while single-celled Amoeba engulfs food using pseudopodia. Respiration has two parts: breathing (movement of air into and out of the body) and cellular respiration (release of energy from glucose using oxygen). Aerobic respiration releases more energy than anaerobic respiration. Different animals use different organs for gas exchange — lungs, gills, spiracles or moist skin — but the purpose is always the same: oxygen in, carbon dioxide out.
Key Terms
NutritionTaking in and using food for energy, growth and repair.
IngestionTaking food into the body.
DigestionBreaking food into simple, absorbable molecules.
AbsorptionMovement of digested food into the blood.
AssimilationUse of absorbed food by body cells.
EgestionRemoval of undigested waste.
SalivaJuice in the mouth; contains salivary amylase.
Gastric juiceStomach juice with HCl, mucus and pepsin.
BileLiver juice that emulsifies fats.
VilliFinger-like projections in small intestine for absorption.
RuminantFour-stomach grass-eater that chews the cud.
RegurgitationBringing food back to the mouth for re-chewing.
PseudopodiaFalse feet of Amoeba, used for moving and eating.
Food vacuoleTiny bag inside Amoeba where food is digested.
BreathingPhysical movement of air in and out of lungs.
Cellular respirationRelease of energy from glucose inside cells.
Aerobic respirationRespiration with oxygen; releases much energy.
Anaerobic respirationRespiration without oxygen; releases little energy.
Lactic acidProduct of anaerobic respiration in muscles.
DiaphragmDome-shaped muscle below the lungs.
AlveoliTiny air sacs in lungs where gas exchange happens.
GillsRespiratory organs of fish.
SpiraclesBreathing holes on an insect's body.
Trachea (windpipe)Tube carrying air from throat to lungs.
NCERT Exercises — Solutions
Q1
Name the five stages of nutrition in animals and give one sentence describing each.
(i) Ingestion — taking food into the body through the mouth.
(ii) Digestion — breaking food into simple, small molecules using teeth and digestive juices.
(iii) Absorption — digested food passing through the intestinal wall into the blood.
(iv) Assimilation — body cells using the absorbed nutrients for energy, growth and repair.
(v) Egestion — removal of undigested waste from the body through the anus.
(ii) Digestion — breaking food into simple, small molecules using teeth and digestive juices.
(iii) Absorption — digested food passing through the intestinal wall into the blood.
(iv) Assimilation — body cells using the absorbed nutrients for energy, growth and repair.
(v) Egestion — removal of undigested waste from the body through the anus.
Q2
Fill in the blanks:
(a) The enzyme in saliva that breaks down starch is called ______.
(b) Bile is made in the ______ and stored in the ______.
(c) The finger-like projections on the inner wall of the small intestine are called ______.
(d) The four chambers of a cow's stomach are rumen, reticulum, ______ and ______.
(a) salivary amylase. (b) liver; gall bladder. (c) villi. (d) omasum; abomasum.
Q3
Differentiate between herbivores and carnivores on the basis of their teeth. Give one example of each.
| Feature | Herbivore | Carnivore |
|---|---|---|
| Incisors | Flat, chisel-like for cutting grass | Small and sharp |
| Canines | Very small or absent | Long, pointed, strong |
| Molars | Broad, flat for grinding | Sharp, jagged for tearing meat |
| Example | Cow, goat | Lion, tiger |
Q4
Describe how Amoeba takes in food. Draw a simple diagram in your notebook.
When a food particle comes close, Amoeba pushes out temporary finger-like extensions of its body called pseudopodia from two sides. The pseudopodia surround the food particle completely and then fuse, trapping the food inside a tiny bag called a food vacuole. Digestive juices inside the vacuole break the food down. The useful nutrients spread into the cell. The remaining waste is thrown out when a spot on the cell surface opens briefly. This type of feeding is called holozoic nutrition.
Q5
Why is the process of digestion in ruminants considered different from that in humans?
Ruminants like cows and buffaloes eat grass, which is mainly cellulose — something their own digestive juices cannot break. So they have four stomach chambers (rumen, reticulum, omasum, abomasum) instead of one. Grass is first stored in the rumen, where bacteria partly digest the cellulose. Small balls (cud) are then brought back to the mouth for a second, slow chewing — a process called regurgitation. After re-swallowing, the food passes through the other chambers for complete digestion. Humans have a single stomach, cannot digest cellulose, and do not chew food twice.
Q6
Distinguish between breathing and respiration.
| Breathing | Cellular respiration |
|---|---|
| A physical process — air moves in and out of lungs | A chemical process — glucose is broken down inside cells |
| Happens in the lungs (or gills/skin/tracheae) | Happens in every living cell of the body |
| Does not directly release energy | Releases the energy stored in food |
| Needs special organs | Needs no organ — every cell does it |
Q7
Write the word equation for aerobic and anaerobic respiration. Why does anaerobic respiration give less energy?
Aerobic (with oxygen): Glucose + Oxygen → Carbon dioxide + Water + a lot of energy.
Anaerobic (without oxygen): Glucose → Lactic acid + a little energy (in muscles). In yeast: Glucose → Alcohol + CO₂ + a little energy.
Anaerobic respiration breaks glucose only partly — the end product (lactic acid or alcohol) still contains plenty of stored energy. Aerobic respiration breaks glucose completely all the way to CO₂ and water, so it releases much more energy.
Anaerobic (without oxygen): Glucose → Lactic acid + a little energy (in muscles). In yeast: Glucose → Alcohol + CO₂ + a little energy.
Anaerobic respiration breaks glucose only partly — the end product (lactic acid or alcohol) still contains plenty of stored energy. Aerobic respiration breaks glucose completely all the way to CO₂ and water, so it releases much more energy.
Q8
Draw a labelled diagram of the human respiratory system showing nostrils, trachea, lungs and diaphragm. (Describe the key parts if you cannot draw here.)
Air enters through the nostrils, passes down the trachea (windpipe), which splits into two bronchi. Each bronchus enters a lung and branches into finer tubes ending in millions of tiny air sacs called alveoli. Below the lungs lies the diaphragm, a dome-shaped muscle. When you breathe in, the diaphragm flattens and the ribs lift — the chest expands, and air rushes into the lungs. When you breathe out, the diaphragm curves up again and pushes air out. (Refer to Fig. 9.8 in Part 3.)
Q9
Match the animal with its respiratory organ:
(i) Fish (ii) Cockroach (iii) Earthworm (iv) Frog (v) Human
(a) Skin (b) Spiracles & tracheae (c) Gills (d) Lungs (e) Lungs + moist skin
(i) Fish → (c) Gills. (ii) Cockroach → (b) Spiracles & tracheae. (iii) Earthworm → (a) Skin. (iv) Frog → (e) Lungs + moist skin. (v) Human → (d) Lungs.
Q10
A student holds his breath for as long as possible. Explain step-by-step what happens inside the body that finally forces him to breathe again.
Step 1: During breath-holding, no fresh air enters the lungs. The cells keep using oxygen from the blood, so the oxygen level slowly drops.
Step 2: At the same time, cells keep producing carbon dioxide, which cannot leave — so CO₂ in the blood rises.
Step 3: A small area in the brain (the respiratory centre) senses the rise in CO₂ (more than the drop in O₂).
Step 4: The brain sends a strong signal to the diaphragm and rib muscles, forcing a breath.
This is why most people cannot hold their breath beyond about 30–60 seconds — the brain's safety signal always takes over.
Step 2: At the same time, cells keep producing carbon dioxide, which cannot leave — so CO₂ in the blood rises.
Step 3: A small area in the brain (the respiratory centre) senses the rise in CO₂ (more than the drop in O₂).
Step 4: The brain sends a strong signal to the diaphragm and rib muscles, forcing a breath.
This is why most people cannot hold their breath beyond about 30–60 seconds — the brain's safety signal always takes over.
Q11
Why does bread rise when yeast is added to the dough? Which type of respiration is responsible?
Yeast performs anaerobic respiration (without oxygen): Glucose → Alcohol + Carbon dioxide + small energy. The CO₂ gas released forms tiny bubbles that get trapped in the sticky dough. As bubbles grow, the dough swells — this is why bread "rises". During baking, the alcohol evaporates and the bubbles expand further, giving bread its soft, airy texture.
Q12
Give one reason for each of the following:
(a) We should chew food slowly.
(b) Insects stay small in size.
(c) The stomach's inner wall has a thick layer of mucus.
(d) Frogs must live close to water.
(a) Chewing slowly breaks food into smaller pieces and mixes it with saliva, which starts digestion and helps the stomach work easily.
(b) Insects rely on tracheal tubes to carry air directly to cells. Diffusion can only supply oxygen over short distances, so insects cannot grow very large.
(c) Mucus protects the stomach wall from the strong hydrochloric acid and pepsin that could otherwise digest the wall itself.
(d) Frogs breathe partly through moist skin. If the skin dries up, gas exchange stops — so frogs need damp surroundings to survive.
(b) Insects rely on tracheal tubes to carry air directly to cells. Diffusion can only supply oxygen over short distances, so insects cannot grow very large.
(c) Mucus protects the stomach wall from the strong hydrochloric acid and pepsin that could otherwise digest the wall itself.
(d) Frogs breathe partly through moist skin. If the skin dries up, gas exchange stops — so frogs need damp surroundings to survive.
Frequently Asked Questions — Life Processes in Animals — Chapter 9 Exercises
What does the topic 'Life Processes in Animals — Chapter 9 Exercises' cover in Class 7 Science?
The topic 'Life Processes in Animals — Chapter 9 Exercises' is part of NCERT Class 7 Science Chapter 9 — Life Processes in Animals. It covers the key ideas of nutrition, digestion, respiration, animals, NCERT exercises, explained through everyday examples, labelled diagrams and hands-on activities drawn from the NCERT Curiosity textbook. Students learn not just definitions but also the reasoning behind each concept so they can answer competency-based questions and assertion–reason items. The lesson helps Class 7 students build a strong base for higher classes by linking each idea to real observations at home, school and in nature, and by preparing them for CBSE school assessments and Olympiads.
Why is 'Life Processes in Animals — Chapter 9 Exercises' important for Class 7 NCERT Science?
'Life Processes in Animals — Chapter 9 Exercises' is important because it builds core scientific thinking that Class 7 students will use throughout middle and secondary school. NCERT Chapter 9 — Life Processes in Animals — introduces nutrition and related ideas that appear again in Class 8, 9 and 10 Science. Mastering this subtopic helps students read labels and safety signs, understand news about science and technology, and perform better in CBSE school exams. The chapter also encourages curiosity and evidence-based thinking — skills that support the National Education Policy (NEP) 2020 focus on conceptual understanding and competency-based learning.
What are the key concepts students should remember from Life Processes in Animals — Chapter 9 Exercises?
The key concepts in 'Life Processes in Animals — Chapter 9 Exercises' for Class 7 Science are: nutrition, digestion, respiration, animals, NCERT exercises. Students should be able to define each term in their own words, give at least one everyday example, and explain how the concept connects to other chapters in NCERT Class 7 Science. For example, linking the idea to daily life — in the kitchen, classroom or outdoors — makes revision easier. Writing short notes, drawing labelled diagrams and solving the NCERT in-text and exercise questions for Chapter 9 will help students retain these concepts for unit tests and the annual CBSE examination.
How is Life Processes in Animals — Chapter 9 Exercises taught using activities in NCERT Curiosity Class 7?
NCERT Curiosity Class 7 Science teaches 'Life Processes in Animals — Chapter 9 Exercises' using an inquiry-based approach with Predict–Observe–Explain activities. Students are asked to make a guess first, then perform a simple experiment with safe, easily available materials, and finally explain what they observed. This matches the NEP 2020 focus on learning by doing. For Chapter 9 — Life Processes in Animals — the textbook includes hands-on tasks, labelled diagrams and questions that build Bloom's Taxonomy skills from Remember (L1) to Create (L6). Teachers use these activities, along with competency-based questions (CBQs) and assertion–reason items, to check real understanding rather than rote memorisation.
How should Class 7 students prepare for the Chapter 9 exercises?
To prepare for the Chapter 9 — Life Processes in Animals — exercises in NCERT Class 7 Science, students should first revise the theory in Parts 1–3 and make a short list of definitions and diagrams for nutrition, digestion, respiration, animals, NCERT exercises. Next, attempt each exercise question on their own before checking the solution. Pay extra attention to MCQs, assertion–reason questions and short-answer items, as these appear in CBSE competency-based tests. Practising with the NCERT Curiosity textbook, the exemplar questions, and the MyAiSchool practice bank helps Class 7 students score better in unit tests and the annual examination.
How does 'Life Processes in Animals — Chapter 9 Exercises' connect to other chapters of Class 7 Science?
'Life Processes in Animals — Chapter 9 Exercises' connects to many other chapters in NCERT Class 7 Science Curiosity. The ideas of nutrition appear again when students study related topics like heat, light, changes, life processes and Earth-Sun-Moon. For example, understanding this subtopic helps in building mental models for later chapters and for Class 8, 9 and 10 Science. Teachers often use cross-chapter questions in CBSE examinations to test whether students can apply what they learned in Chapter 9 — Life Processes in Animals — to new situations. This integrated approach matches the NEP 2020 and NCF 2023 focus on holistic, competency-based learning.
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