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Your guide: Miss AimanThinks the human body is the best-designed machine in the syllabus.
Nutrition is how organisms get and use nutrients. It helps them grow, stay healthy and repair their bodies.
Animals, including humans, cannot make their own food. They get it from other organisms. This is called heterotrophic nutrition.
Food is made of polymers: large molecules like carbohydrates, proteins and fats. They cannot pass through cell membranes, so digestion breaks them into small, soluble monomers such as sugars, amino acids and fatty acids.
1. Ingestion: taking in food and drinks through the mouth.
2. Digestion: breaking food into smaller parts the body can absorb.
3. Absorption: moving nutrients from the digested food into the blood or lymph.
4. Assimilation: using the absorbed nutrients in cells and tissues.
5. Egestion: removing undigested food and waste from the body.
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Nutrition is how organisms get and use nutrients. It helps them grow, stay healthy and repair their bodies.
Animals, including humans, cannot make their own food. They get it from other organisms. This is called heterotrophic nutrition.
Food is made of polymers: large molecules like carbohydrates, proteins and fats. They cannot pass through cell membranes, so digestion breaks them into small, soluble monomers such as sugars, amino acids and fatty acids.
1. Ingestion: taking in food and drinks through the mouth.
2. Digestion: breaking food into smaller parts the body can absorb.
3. Absorption: moving nutrients from the digested food into the blood or lymph.
4. Assimilation: using the absorbed nutrients in cells and tissues.
5. Egestion: removing undigested food and waste from the body.
Big food molecules are useless to a cell until they are broken small enough to cross its membrane. That is the whole point of digestion.
Q1. A boy eats an egg. Its protein ends up as new muscle. Name the steps in order.
Ingestion, digestion, absorption, assimilation. Undigested parts leave by egestion.
Q2. Is a human autotrophic or heterotrophic? Give the reason from your book.
Heterotrophic: we get our food from other organisms.
✗ Absorption and assimilation are the same thing.
✓ Absorption moves nutrients into blood or lymph; assimilation is cells using them.
✗ Cells can take in starch and proteins directly.
✓ Polymers cannot pass through cell membranes; they must be digested to monomers first.
✗ Humans make some of their own food, like plants.
✓ Humans cannot make their own food; our nutrition is heterotrophic.
1. Using absorbed nutrients in cells and tissues is called:
(c) p. 2, step 4.
2. Which is the correct order?
(a) p. 2: food must be taken in and digested before it can be absorbed and used.
3. Why must food polymers be digested?
(d) p. 2.
4. Organisms that obtain food by consuming other organisms show:
(b) p. 2 box.
5. Absorbed nutrients move into:
(b) p. 2, step 3.
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