STD 7 Basic Science: Chapter 04 Through the Alimentary Canal - Questions and Answers / Teaching Manual


Study Notes for Class 7 Basic Science (English Medium) അന്നപഥത്തിലൂടെ | Text Books Solution Basic Science (English Medium) Chapter 04 Through the alimentary canal - Teaching Manual / Teachers Handbook

SCERT Solutions for STD VII Basic Science Chapterwise
ഈ അധ്യായത്തിന്റെ Teachers Handbook, Teaching Manual എന്നിവ ഡൗൺലോഡ് ചെയ്യാനുള്ള ലിങ്ക് ചോദ്യോത്തരങ്ങളുടെ അവസാനം നൽകിയിട്ടുണ്ട്.

Chapter 04: Through the Alimentary Canal - Questions and Answers
1. What is nutrition?
Answer: The process of intake and utilization of food by organisms is called nutrition.

2. Don’t you know which process is indicated in the picture?

Answer: photosynthesis
• What are the factors required for photosynthesis?
Answer: Sunlight, carbon dioxide, chlorophyll, water and minerals
• Which is the gas received by plants during photosynthesis?
Answer: Carbon dioxide
• Which is the gas given out?
Answer: Oxygen

3. What are autotrophs?
Answer: The organisms which synthesise their own food are called autotrophs.

4. What are called heterotrophs?
Answer: There are organisms that are unable to synthesize their own food and therefore depend on other organisms for food. They are called heterotrophs.

5. Observe the pictures given below.
• Classify the plants indicated in the pictures and note them down in the given table.
6. What may be the reason for the drying up of the branch on which Loranthus grows?
Answer: Loranthus is a partial parasite that grows on the branches of woody trees. Its leaves prepare their own food by absorbing minerals and water from the host plant. As a result, the host plant loses all the necessary minerals and water required for the growth of its body. It is the reason for the drying up of the branch on which Loranthus grows.

7. Write examples for external and internal parasites?
Answer: Louse and flea are examples of external parasites. The worm is an example of an internal parasite.

8. Photosynthesis takes place in insectivorous plants too. Then why do they catch insects?
Answer:  The insectivorous plants grow in soil that does not contain sufficient nitrogen minerals. It is to overcome this situation that such plants acquire the ability to catch insects. They obtain the required nitrogen through the digestion of the body of these insects.

9. What change does the food undergo inside the mouth? What role do lips, teeth and tongue play in this? Observe the changes on your own while having food and write down your observations.
Answer: When we eat, our teeth tear, cut, and grind food in preparation for swallowing. Thetonguehelpsto push food to the teeth. The lips help to keep the food from going out of the mouth. While grinding the food, it is well mixed with saliva which helps in softening food particles. 

10. Why does the tooth, which does not decay even when buried for long in the earth, decay easily inside the mouth?
Answer: Enamel is the outermost layer of teeth. It is the hardest material in the human body. It is not easy to destroy enamel. When food remains stuck to teeth, bacteria feed on them. Asa result, lactic acid is produced, which causes the destruction of enamel.

11. Listen to what Hima and Suresh Say.
Which habit should be practised for the health of teeth? Why?
Answer: Hima's habit should be practised for the health of teeth. Brushing at night is actually more important. Because at night there will be more food particles which will cause tooth decay.

12. What is known as milk teeth?
Answer: It is at the age of approximately six months that teeth start sprouting. These teeth are known as milk teeth.

13. What are permanent teeth?
Answer: The milk teeth start falling from the age of six. Permanent teeth are those which appear after that.

14. Write a short note on different types of teeth present in our body.
Answer:
i. Incisor
• Eight teeth in the front-four above and four below.
• Helps to bite and cut.
ii. Canine
• Four teeth near the incisors on both sides above and below.
• Helps to tear off foodstuff.
iii. Premolar
• Eight teeth next to canines on both sides above and below.
• Helps to chew and grind.
iv. Molar
• Twelve teeth next to premolars above and below.
• Helps to grind and crush.

15. Premolars and molars are generally called .............
Answer: Molar teeth

16. How many teeth are present in an adult human being?
Answer: 32

17. How is the shape of animals' teeth related to their food habit?
Answer: Carnivores have canine teeth which can tear off food. But herbivores have teeth help in cutting, chewing and grinding food.

18. What is called peristalsis?
Answer: Food reaches the stomach from the mouth through the oesophagus. It is the wave-like movement of the oesophagus which enables this. This is called peristalsis,

19. Write a short note on the digestion of food in the stomach?
Answer: Due to the movement of the stomach wall, food is rendered paste-like inside the stomach. The digestive enzymes produced by the stomach digests food chemically too.

20. Write a short note on the small intestine?
Answer: Small intestine is about six metres long. Digestion of food is completed here. The nutrients in the digested food are absorbed into the blood.

21. Write a short note on the large intestine?
Answer: Large intestine is the broader intestine following the small intestine and is about one and a half metres long. The absorption of water containing minerals and salts takes place here.

22. Look at the picture and label the parts marked in it.
Answer:
1) Mouth
2) Oesophagus
3) Stomach
4) Small intestine
5) Large intestine
6) Rectum

23. What are the adverse effects of alcoholism on the digestive system?
Answer:
• Liquor afflicts wounds on the soft layers of the stomach. This results in
ulcers.
• Excessive alcoholism causes liver cirrhosis.
• Liquor causes cancer in the mouth, oesophagus, liver and large intestine.

24. What are the different stages in the process of nutrition in amoeba? Complete the flowchart. (TextBook Page: 58)
25. Write a short note on the Stages in the process of nutrition?
Answer: The first stage in the process of nutrition is ingestion. Digestion is the process in which the organic factors present in the food are broken down into simple components that can be absorbed by the body. The process of the digested food being received into the body is absorption. Assimilation is the process in which absorbed components become part of the body. The byproducts of metabolic reactions which are not useful to the body are eliminated through the process called excretion.

26. Complete the flowchart, adding the stage of assimilation.
27. Look at the illustration:
i. Which are the components reaching blood?
Answer: Oxygen, carbon dioxide, urea, nutrients.
ii. Which among these are required for the body?
Answer: Oxygen and nutrients
iii. How are the unwanted substances eliminated?
Answer: Carbon dioxide is eliminated through respiration. Excess urea is filtered and expelled in the form of urine.

28. What is the function of the kidney?
Answer: Excess urea, water and Salts in the blood are filtered and expelled in the form of urine.

29. What are the causes of urinary infections?
Answer: Not passing urine when required, not drinking enough water, not
maintaining hygiene etc. will Cause urinary diseases.

30. What all are expelled from the body through sweat?
Answer: Excess water and Salts in the body are eliminated through sweat.

31. What is called dehydration?
Answer: The condition of excessive loss of water and salts from the body is called dehydration.

32. What is the advantage of sweating?
Answer: Sweating helps to regulate and maintain our body temperature.

33. Which gland produces sweat in our body?
Answer: Sweat is produced by sweat glands in the skin

34. What is the importance of carefully cleaning all body parts while bathing?
Answer: Sweat and other wastes are expelled through the minute pores of the skin. They accumulate on the skin. Hence the Skin has to be cleaned.

35. What are the methods plants adopt to eliminate wastes.
Answer:
• Waste materials are stored in the bark which later gets detached.
• Waste materials are expelled as exudates from them.

Let us Assess

1. Food is to be thoroughly chewed and ground while eating. Why?
(a) To feel the taste of food
(b) To give exercise to teeth
(c) To facilitate digestion
(d) To mix hydrochloric acid in food
Answer:
(c) To facilitate digestion

2. The levels of Oxygen and Carbon dioxide are maintained constant in the atmosphere
a. Due to respiration by animals
b. Due to photosynthesis by plants
c. Due to the processes of respiration
and photosynthesis
d. Due to a decrease in plant populations
Answer:
c. Due to the processes of respiration and photosynthesis

3. Complete the flow chart adding the different stages, related organs and functions of the process of nutrition.
Functions of the process of nutrition.
Ingestion- Intake of food
Digestion-organic factors present in the food are broken down into simple components that can be absorbed by the body.
Absorption- Nutrients in the food are absorbed into the blood.
Assimilation-absorbed components become part of the body.
Excretion- The byproducts of metabolic reactions which are not useful to the body are eliminated through the process called excretion.





👉Basic Science TextBook (pdf) - Click here 
TEACHING APTITUDE TEST (K-TET, C-TET,, etc.) ---> Click here