CLASS-8 SUBJECT -SCIENCE CHAPTER-8 CELL STRUCTURE AND FUNCTIONS

 EVENTS CONVENT HIGH SCHOOL

16/11/2021      CLASS - 8   SESSION 2021-22
SUBJECT :  SCIENCE

CHAPTER-8 CELL STRUCTURE AND FUNCTIONS
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Question 1.Indicate whether the following statements are True (T) or False (F).
(a) Unicellular organisms have a one-celled body.
(b) Muscle cells are branched.
(c) The basic living unit of an organism is an organ.
(d) Amoeba has an irregular shape.
Answer:
(a) True
(b) True
(c) False
(d) True

Question 2.Make a sketch of the human nerve cell. What function do nerve cells perform?
Answer:
Function of nerve cells: The function of the nerve cell is to receive and transfer messages, it helps to control and coordinate the working of different parts of the body.

Question 3.Write short notes on the following.
(a) Cytoplasm
(b) Nucleus of a cell
Answer:
(a) Cytoplasm: The jelly-like substance found between the nucleus and the cell membrane is called cytoplasm. It is made up of basic elements like C, H, O, N. Various other components or organelles, like mitochondria, Golgi bodies, ribosomes, etc., of cells are present in the cytoplasm.

(b) Nucleus of a cell: Nucleus of a cell is an important component of the living cell. It is located at the centre of the cell. It is separated from the cytoplasm by a membrane called nuclear membrane. It contains genetic material.

Question 4.Which part of the cell contains organelles?
Answer:
Cytoplasm

Question 5.Make sketches of animal and plant cells. State three differences between them.
Answer:

Plant cells	Animal cells
(i) The outermost covering is a cell wall and it is made of cellulose.	(i) The outermost covering of animal cell is the plasma membrane.
(ii) Plastids are present in plant cells.	(ii) Plastids are absent in animal cells.
(iii) Large vacuoles are present in plant cells.	(iii) No or very small vacuoles are present in animal cells.
(iv) It lacks centrosomes and lysosomes.	(iv) They have centrosomes or lysosomes.

Question 6.State the difference between eukaryotes and prokaryotes.
Solution:

Eukaryotes	Prokaryotes
(i) Eukaryotes possess membrane-bound organ­elles.	(i) Prokaryotes lack membrane-bound organelles.
(ii) Nucleus of the cell has nuclear membrane. Example: higher plants and animals.	(ii) Nucleus is not bounded by membrane. Example: bacteria and blue-green algae.

Question 7. Where are chromosomes found in a cell? State their function.
Answer:
Chromosomes are present in the nucleus. The functions of chromosomes is to carry genes on them and to transfer the character from parents to the next generation.

Question 8. ‘Cells are the basic structural units of living organisms.’ Explain.
Answer:
Different cells combine to form tissues and tissues combine to form organs. Similarly, organs combine to form body. Thus they are termed as the basic structural unit of every living organism.

Question 9. Explain why chloroplast are found only in plant cells?
Answer:
Chloroplasts are plastids required for the food making process, called photosynthesis, and thus they are only present in plant cells.

CLASS-7 Subject-Science Chapter-10 Respiration in animals and plants

 EVENTS CONVENT HIGH SCHOOL

16/11/2021      CLASS - 7   SESSION 2021-22
SUBJECT :  SCIENCE

CHAPTER-10 RESPIRATION IN ANIMALS AND PLANTS
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Q1. Why does an athlete breathe faster and deeper than usual after finishing the race?

Answer:
During the run, the demand of energy is high but the supply of oxygen to produce energy is limited. Therefore, anaerobic respiration takes places in the muscle cells to fulfill the demand of energy. After finishing the race, an athlete breathe faster and deeper than usual so that more oxygen is supplied to the cells.

Q2. List the similarities and differences between aerobic and anaerobic respiration.
Answer:
Similarity:
(i) In both aerobic and anaerobic respiration, food is broken down to release energy.
(ii) Both takes place inside cells.
(iii) Both produces byproducts.

Differences:

Aerobic Respiration	Anaerobic Respiration
(i) It takes place in the presence of oxygen.	(i) It takes place in the absence of oxygen.
(ii) Energy is released in higher amount.	(ii) Energy is released in lesser amount.
(iii) Carbon dioxide and water are produced as byproducts.	(iii) Carbon dioxide and water are produced as byproducts.
(iv) It is a slow process.	(iv) It is a fast process.
(v) Examples: Animals and plants cells.	(iv) Examples: Human cells, yeast, Bacteria etc.

Q3. Why do we often sneeze when we inhale a lot of dust-laden air?
Answer:
We often sneeze when we inhale a lot of dust-laden air to expel out these foreign particles. These particles get past the hair in the nasal cavity and irritate the lining of the cavity which results in sneezing.

Q4. Take three test-tubes. Fill each of them with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2 ?
Answer:
Test-tube A will have the highest concentration of CO2 because snail will take in oxygen and gives out CO2.
In test-tubes B and C, the CO2 will be utilized by the water plant for synthesizing food and hence there will be less concentration of CO2 in these.

Q5. Tick the correct answer:
(a) In cockroaches, air enters the body through
(i) lungs
(ii) gills
(iii) spiracles
(iv) skin
Answer: (iii) spiracles
(b) During heavy exercise, we get cramps in the legs due to the accumulation of
(i) carbon dioxide
(ii) lactic acid
(iii) alcohol
(iv) water
Answer: (ii) lactic acid
(c) Normal range of breathing rate per minute in an average adult person at rest is:
(i) 9 – 12
(ii) 15 – 18
(iii) 21 – 24
(iv) 30 – 33
Answer: (ii) 15 – 18
(d) During exhalation, the ribs
(i) move outwards
(ii) move downwards
(iii) move upwards
(iv) do not move at all
Answer: (ii) move downwards

Q6. Match the items in Column I with those in Column II:

Column I	Column II
(a) Yeast	(i) Earthworm
(b) Diaphragm	(ii) Gills
(c) Skin	(iii) Alcohol
(d) Leaves	(iv) Chest cavity
(e) Fish	(v) Stomata
(f) Frog	(vi) Lungs and skin
–	(vii) Tracheae

Answer:

Column I	Column II
(a) Yeast	(iii) Alcohol
(b) Diaphragm	(iv) Chest cavity
(c) Skin	(i) Earthworm
(d) Leaves	(v) Stomata
(e) Fish	(ii) Gills
(f) Frog	(vi) Lungs and skin

Q7. Mark T if the statement is true and F if it is false:
(i) During heavy exercise the breathing rate of a person slows down. (T/ F)
(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/ F)
(iii) Frogs breathe through their skins as well as their lungs. (T/ F)
(iv) The fishes have lungs for respiration. (T/ F)
(v) The size of the chest cavity increases during inhalation. (T/ F)
Answer:
(i) F
(ii) F
(iii) T
(iv) F
(v) T

CLASS-7 SUBJECT-SOCIAL SCIENCE (CIVIC) CHAPTER-7 MARKET AROUND US

  EVENTS CONVENT HIGH SCHOOL

11/11/2021      CLASS- 7   SESSION 2021-22
SUBJECT :  SOCIAL SCIENCE (CIVIC)

CHAPTER-7 mARKET AROUND US
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I. VERY SHORT ANSWER TYPE QUESTIONS:-

1. Why is a weekly market called so?
Answer: A weekly market is called so because it is held a specific day of the week.

2. Why is there a competition among the shops in the weekly market? [V. Imp.]
Answer: In the weekly market there are many shops that sell the same goods. This creates competition among them.

3. Who is Scunner? What does he do?
Answer: Sameer is a small trader in the weekly market. He buys clothes from a large trader and sells them in six different markets in a week.

4. Give some examples of roadside stalls.
Answer: Vegetable hawker, fruit vendor, mechanic.

5. How are shops in the neighbourhood useful?
Answer: These types of shops are close to our home and we can go there any time. As the buyer and seller know each other these shops also provide goods on credit.

6. Where are the goods produced?
Answer: Goods are produced in factories, on farms, and in homes.

7. Why do we not buy directly from the producer?    [V. Imp.]
Answer: It is because the producer is not interested in selling goods in small quantities. 9*

II. SHORT ANSWER TYPE QUESTIONS:-

1. Write in brief about shopping complexes and malls.
Answer: Shopping complexes and malls are usually found in urban areas. These are large multi-storeyed air-conditioned buildings with shops on different floors. These shops sell both branded and non-branded goods. Fewer people visit malls because they sell costly items. Only well-to-do people can afford to buy these items.

2. What is the job of a wholesale trader?  [V. Imp.]
Answer: A wholesale trader buys goods from the producer in large quantities. He then sells them to other traders, say small traders. These small traders sell different items to the final consumer. Thus, the wholesale trader establishes link between the producer and the consumer. It is through these links of traders that goods reach faraway places.

3. How are shop owners in a weekly market and those in a shopping complex very different people?  [V. Imp.]
Answer: Both are undoubtedly different people.
(a) The shop owners in a weekly market are small traders who run their shop with little money. On the other hand, the shop owners of a shopping complex are big parties. They have a lot of money to spend on their shops.

(b) What these two types of shop owners earn is also not equal. The weekly market trader earns little compared to the profit of a regular shop owner in a shopping complex.

4. Write a brief note on ‘Aftab—the wholesaler in the city’.
Answer: Aftab is a wholesaler of vegetables. His work usually starts at around 2 o’clock in the early morning. This is the time when vegetables reach the market or mandi and with them start the activities. The vegetables come in trucks, matadors, etc. and soon the process of auctions begins. Aftab participates in this auction and decides what he will buy. He buys vegetables in bulk. After that, he sells them to hawkers and shopkeepers who usually come to him around six in the morning.