Life Processes in Animals Class 7 - Chapter 9 Curiosity

Q 1
Question
Complete the journey of food through the alimentary canal by filling up the boxes with appropriate parts —
Food → Mouth → [___] → Stomach → [___] → [___] → Anus
🔗 Concept:
9.1.1
Digestion in Human Beings
Mouth
Oesophagus
Stomach
Large Intestine
Small Intestine
Anus
Blank diagram for filling in alimentary canal parts
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Food → Mouth → Oesophagus (Food pipe) → Stomach → Small intestine → Large intestine → Anus
Explanation
After the mouth, food enters the oesophagus (food pipe) through which it reaches the stomach.
From the stomach, food moves to the small intestine where most digestion and absorption happens.
The large intestine absorbs water — undigested waste then passes out through the anus.
The alimentary canal is a continuous tube: Mouth → Oesophagus → Stomach → Small intestine → Large intestine → Anus.

Q 2
Question
Sahil placed some pieces of chapati in test tube A. Neha placed chewed chapati in test tube B, and Santushti took boiled and mashed potato in test tube C. All of them added a few drops of iodine solution to their test tubes — A, B, and C, respectively. What would be their observations? Give reasons.
🔗 Concept:
9.1.1
Stop 1 — The Mouth
A
B
C
Three test tubes with iodine test showing different colour results
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A: blue-black. B: no change (or very light blue-black). C: blue-black.
Explanation
Test tube A (chapati):
Turns blue-black. Chapati contains starch; iodine reacts with starch to give blue-black colour.
Test tube B (chewed chapati):
No change or very light blue-black. Saliva in the mouth broke down the starch into sugar during chewing — little or no starch remains to react with iodine.
Test tube C (boiled mashed potato):
Turns blue-black. Potato contains starch; iodine reacts with it to give blue-black colour.
Starch turns blue-black with iodine. Chewed chapati shows less starch because saliva converts starch into sugar in the mouth.

Q 3
Question
What is the role of the diaphragm in breathing?
(i) To filter the air
(ii) To produce sound
(iii) To help in inhalation and exhalation
(iv) To absorb oxygen
🔗 Concept:
9.2.1
Respiration in Humans
Air is drawn in
Air is forced out
Ribs move outwards
Ribs move back
Diaphragm moves downward
Diaphragm moves upward
Diaphragm movement during inhalation and exhalation
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Correct option: (iii) To help in inhalation and exhalation.
Explanation
The diaphragm is a dome-shaped muscle below the lungs.
During inhalation: it moves downward, increasing chest space so air enters the lungs.
During exhalation: it moves upward, reducing chest space and pushing air out of the lungs.
The diaphragm controls breathing by changing the space inside the chest.

Q 4
Question
Match the following:
Name of the part — Functions
(i) Nostrils — (a) fresh air from outside enters
(ii) Nasal passages — (b) exchange of gases occurs
(iii) Windpipe — (c) protects lungs
(iv) Alveoli — (d) tiny hair and mucus help to trap dust and dirt from the air we breathe
(v) Ribcage — (e) air reaches our lungs through this part
🔗 Concept:
9.2.1
How Do We Breathe?
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(i)→(a), (ii)→(d), (iii)→(e), (iv)→(b), (v)→(c)
Explanation
(i) Nostrils → (a) fresh air from outside enters through the nostrils.
(ii) Nasal passages → (d) tiny hair and mucus in nasal passages trap dust and dirt.
(iii) Windpipe → (e) air travels through the windpipe to reach the lungs.
(iv) Alveoli → (b) exchange of gases (O₂ in, CO₂ out) occurs in the alveoli.
(v) Ribcage → (c) the ribcage protects the lungs.
Each part of the respiratory system has a specific job in getting air to the lungs and keeping them safe.

Q 5
Question
Anil claims to his friend Sanvi that respiration and breathing are the same process. What question(s) can Sanvi ask him to make him understand that he is not correct?
🔗 Concept:
9.2.1
How Does Gas Exchange Happen?
Breathing (lungs, physical) vs Respiration (cells, chemical)
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Sanvi can ask: "Is breathing a physical or chemical process? Where does respiration happen?"
Explanation
Breathing is a
physical process
— moving air in and out of the lungs. It happens in the lungs.
Respiration is a
chemical process
— breaking down glucose using oxygen to release energy. It happens inside every cell of the body.
Sanvi can ask: "Can you hold your breath and still have respiration happening?" (Yes! Cells continue respiration briefly even when we hold our breath.)
Sanvi can ask: "Does breathing happen inside cells?" (No — breathing moves air to the lungs; respiration happens inside cells.)
Breathing = physical (air in/out, lungs). Respiration = chemical (glucose + O₂ → energy, inside cells). They are different processes.

Q 6
Question
Which of the following statements is correct and why?
Anu: We inhale air.
Shanu: We inhale oxygen.
Tanu: We inhale air rich in oxygen.
🔗 Concept:
9.2.1
What Do We Breathe Out?
Tanu's statement is the most accurate description
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Only Tanu is correct: "We inhale air rich in oxygen."
Explanation
Anu's statement
("We inhale air") is too vague. Air is a mixture of gases including oxygen, nitrogen, and others. Saying just "air" does not capture what is important about what we breathe in.
Shanu's statement
("We inhale oxygen") is wrong. We do not inhale pure oxygen — we inhale air, which contains about 21% oxygen along with nitrogen and other gases.
Tanu's statement
("We inhale air rich in oxygen") is correct and most precise. Air is approximately 21% oxygen — it is rich in oxygen, not pure oxygen.
We inhale air (a mixture), not pure oxygen. The air we breathe in is rich in oxygen (~21%). Tanu is the most accurate.

Q 7
Question
We often sneeze when we inhale a lot of dust-laden air. What can be possible explanations for this?
🔗 Concept:
9.2.1
How Do We Breathe?
Sneezing as a protective reflex against dust
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Sneezing is a protective reflex that removes dust and irritants from the nose.
Explanation
When we inhale dust-laden air, dust particles enter through the nostrils.
Tiny hair and mucus in the nasal passages trap most of the dust, but some particles can irritate the lining of the nasal passages.
This irritation triggers a sneezing reflex — sneezing forcefully expels air from the nose and mouth.
This removes the irritating dust particles and prevents them from going deeper into the respiratory system (windpipe and lungs).
Sneezing is the body's defence mechanism to clear dust and irritants from the nose before they reach the lungs.

Q 8
Question
Paridhi and Anusha of Grade 7 started running for their morning workout. After they completed their running, they counted their breaths per minute. Anusha was breathing faster than Paridhi. Provide at least two possible explanations for why Anusha was breathing faster than Paridhi.
🔗 Concept:
9.2.1
How Do We Breathe?
Paridhi and Anusha after running, with different breathing rates
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Two possible explanations: different fitness levels, or different running intensity.
Explanation
Explanation 1 — Fitness level:
Paridhi may be more physically fit than Anusha. A fitter person's body uses oxygen more efficiently — so they need less rapid breathing after exercise. Anusha, being less fit, needs to breathe faster to get enough oxygen.
Explanation 2 — Running intensity:
Anusha may have run faster or with more intensity. When muscles work harder, they need more oxygen to release energy through respiration. The body breathes faster to supply this extra oxygen.
Explanation 3 — Body size or health:
Anusha may have a larger body size or a respiratory condition that means her body needs to breathe more times per minute to get the same amount of oxygen as Paridhi.
After exercise, breathing rate increases to supply more oxygen for respiration. Fitter people or those who ran less intensely recover faster.

Q 9
Question
Yadu conducted an experiment to test his idea. He took two test tubes, A and B, and added a pinch of rice flour to the test tubes, half-filled with water and stirred them properly. To test tube B, he added a few drops of saliva. He left the two test tubes for 35–45 min. After that, he added iodine solution into both the test tubes. Experimental results are as shown in Fig. 9.15.
What do you think he wants to test?
🔗 Concept:
9.1.1
Stop 1 — The Mouth
Fig. 9.15: Experimental results showing test tube A blue-black, test tube B clear
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Yadu wants to test whether saliva can break down starch in rice flour into simpler sugars.
Explanation
Test tube A (rice flour + water, no saliva): iodine turned blue-black — starch is present.
Test tube B (rice flour + water + saliva): iodine showed no colour change — starch is no longer present.
This shows that saliva broke down the starch in rice flour into simpler sugars over 35–45 minutes.
The experiment demonstrates that saliva contains a digestive juice that breaks down starch — which is why starchy food tastes sweet when chewed for a long time.
Yadu is testing the digestive action of saliva on starch. The results confirm that saliva breaks starch into sugar.

Q 10
Question
Rakshita designed an experiment taking two clean test tubes, A and B and filled them with lime water as shown in the figure. In test tube A, the surrounding air that we inhale was passed on by sucking air from the pipe, and in test tube B, the exhaled air was blown through the pipe (Fig. 9.16). What do you think she is trying to investigate? How can she confirm her findings?
🔗 Concept:
9.2.1
What Do We Breathe Out?
Fig. 9.16: Rakshita's experimental setup comparing inhaled and exhaled air
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Rakshita is investigating whether exhaled air contains more carbon dioxide than inhaled air.
Explanation
Test tube A (inhaled air): lime water stays clear — inhaled air has very little carbon dioxide (~0.04%).
Test tube B (exhaled air): lime water turns milky — exhaled air contains more carbon dioxide (~4–5%).
Lime water turns milky when it reacts with carbon dioxide — this confirms the presence of CO₂ in exhaled air.
To confirm findings:
She can repeat the experiment multiple times to check for consistent results. She can also compare the time taken for lime water to turn milky in test tube B — faster clouding means more carbon dioxide.
Exhaled air has more CO₂ than inhaled air. Lime water turning milky is the confirmation test.

What are the good practices?
Gather information from books, newspapers, or conversations with elders.
Prepare a report and present it in class.
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Key Points
Good oral hygiene prevents tooth decay, bad breath, and gum disease.
Good Practices
Brush teeth twice a day — morning and before bed.
Clean the tongue with a tongue cleaner every day.
Rinse mouth with water after every meal to remove food particles.
Avoid too much sugar — bacteria in the mouth convert sugar to acid, which damages teeth.
Elders traditionally used neem twigs (datun) — neem has natural antibacterial properties.
Visit a dentist regularly for check-ups.
Clean teeth, clean tongue, and rinsing after meals are the three most important daily habits for oral hygiene.

Find out different ways to.
Suggest some food items that help maintain good digestive health.
Make a report and present it in class.
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Key Points
A healthy digestive system needs fibre, water, and regular meal timings.
Good Practices
Eat fibre-rich foods — fruits, vegetables, whole grains (like jowar, bajra, ragi).
Drink enough water — helps the large intestine absorb water and pass stool easily.
Eat meals at proper timings — irregular eating disturbs digestive rhythm.
Avoid overeating — the stomach needs space to churn food properly.
Eat fermented foods like curd and buttermilk — they contain gut-friendly bacteria.
Chew food properly — mechanical digestion in the mouth eases the work of the stomach.
Fibre, water, fermented foods, and mindful eating are the pillars of a healthy digestive system.

Using coloured clay prepare a.
Label all parts using black paper strips.
Display it in class.
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Key Points
Label all 7 parts of the alimentary canal plus liver and pancreas.
Parts to Include and Suggested Colours
Mouth
— red clay. Starting point of digestion.
Oesophagus (food pipe)
— pink clay, narrow tube from mouth to stomach.
Stomach
— orange clay, J-shaped pouch.
Small intestine
— yellow clay, coiled tube about 6 metres long.
Large intestine
— brown clay, wider but shorter frame around the small intestine.
Liver
— dark red clay, largest gland, sits above the stomach.
Pancreas
— green clay, sits behind the stomach.
Rectum and Anus
— brown clay, final outlet.
Use black paper strip labels and arrows to show the direction food travels from mouth to anus.

What is air quality and?
Find out the effect of air quality on the respiratory systems of people working in various fields — farmers, factory workers, or street vendors.
Prepare a report on your findings.
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Key Points
AQI (Air Quality Index) measures how polluted the air is — higher AQI means worse air and greater health risk.
Key Facts
AQI scale:
0–50 = Good, 51–100 = Satisfactory, 101–200 = Moderate, 201–300 = Poor, 301+ = Very poor / hazardous.
Farmers:
Exposed to pesticide sprays and dust during harvesting — can cause coughing, asthma, and lung damage over time.
Factory workers:
Inhale chemical fumes, smoke, and fine particles — long-term exposure causes occupational lung diseases.
Street vendors:
Constantly breathe vehicle exhaust and road dust — high risk of respiratory infections and reduced lung function.
Wearing masks, taking breaks in fresh air, and using air purifiers help reduce risk.
Poor air quality damages the respiratory system over time — people working outdoors or near pollution sources face the highest risk.

Read about the box-breathing technique (Fig. 9.17: Breathe in 4 sec → Hold 4 sec → Breathe out 4 sec → Hold 4 sec).
What are its benefits? Research and present your findings.
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Key Points
Box breathing is a slow, controlled breathing technique that calms the body and improves focus.
How It Works and Its Benefits
The 4-step cycle:
Inhale for 4 seconds → Hold for 4 seconds → Exhale for 4 seconds → Hold for 4 seconds. Repeat.
Calms the nervous system:
Slow breathing reduces the heart rate and tells the body it is safe — reduces stress and anxiety.
Improves lung capacity:
Deep, controlled breathing uses more of the lungs' volume than normal shallow breathing.
Improves focus and concentration:
Used by athletes, soldiers, and students before exams to stay calm and alert.
Related traditions:
Similar to pranayama — rhythmic breath control has been practised in India for centuries for the same benefits.
Box breathing improves respiratory health, reduces stress, and sharpens concentration — all from 4 slow, controlled breaths.

Both birds and mammals have, but birds can fly at high altitudes where oxygen levels are low.
How might their respiratory system be adapted to help them survive in such conditions?
Research and present your findings.
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Key Points
Birds have a highly efficient respiratory system that extracts more oxygen per breath than mammals can.
Key Adaptations
Air sacs:
Birds have a system of air sacs (like extra chambers) connected to the lungs. These store air and push it through the lungs in one continuous flow.
One-way airflow:
In mammals, air goes in and out the same way — so used air mixes with fresh air. In birds, fresh air flows through the lungs in one direction only — giving more oxygen per breath.
More efficient gas exchange:
Because fresh air is always flowing through, birds extract more oxygen even when it is thin at high altitudes.
Example:
Bar-headed geese fly over the Himalayas at altitudes where oxygen is very low — their efficient respiratory system makes this possible.
Birds extract oxygen more efficiently than mammals because fresh air flows through their lungs continuously — this is how they fly at high altitudes with little oxygen.
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