Class 6 General Science (G.Sc.) Notes: - Unit-3: Photosynthesis and Respiration in Plants: Solved Short Questions and Answers

General Science (G.Sc.) Class 6 Notes

Based on the Single National Curriculum, PK

(New Book/New Syllabus for 2023-2024 Exams and onward)

National Book Foundation
as
Federal Textbook Boards, Islamabad

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Q. "Write Short Answers"

Q(i).  Define upper and lower epidermis.

Ans: 

The upper layer of a leaf is called upper epidermis. 

The lower layer of a leaf is called lower epidermis.

Lower epidermis has many stomata

Q(ii). Define stomata?

Ans: Each leaf has an openings for exchange of oxygen, carbon dioxide, water vapours in atmosphere is called stomata.

Q(iii).  Define Mesophyll.

Ans: The lens at the end of the tube through which we observe an object is called eyepiece.

Q(iv). Why does leaf look green?

Ans: The leaf looks green because the green coluor of the chlorophyll shows through the clear epidermis. This chlorophyll helps to make food.

Q(v). When the guard cell absorb and release water what effect on stomata?

Ans: When the guard cell absorb water, they sell and the stomata opens. When the guard cells release water, the stomata closes.

Q(vi). Define photosynthesis?

Ans: Plants make their food by using carbon dioxide and water in the presence of sunlight and chlorophyll. This process is called photosynthesis. “Photo” means light and “synthesis” means to make.

Q(vii). Write the equation of synthesis?

Ans: Carbon dioxide + water sun light Glucose + oxygen.

Q(viii). Give importance of photosynthesis.

Ans: Glucose and oxygen are the product of photosynthesis. All living things use these two products in respiration to produce energy. This energy is used to perform different activities.

Q(ix). How light effect in the process of photosynthesis?

Ans: Plants trap light to make food by photosynthesis. Photosynthesis increase as the light intensity increases.

Q(x). How carbon dioxide effect in the process of photosynthesis?

Ans: Carbon dioxide which plants absorb from air is an essential component for photosynthesis. The rate of photosynthesis increases with increasing carbon dioxide. The level of carbon dioxide in air is about 0.03 to 0.04 percentage.

Q(xi). How temperature effect on the process of photosynthesis?

Ans: The higher the temperature, the faster the process of photosynthesis. Normally, plants grow well at 25 – 35 °C. Temperature below 0oC and above 40oC are not suitable for plant growth.

Q(xii). Define chlorophyll?

Ans: Chlorophyll is the green material in plants. That trap light for photosynthesis. It gives green colour to the leaves.

Q(xiii). Define Respiration?

Ans: Humans take oxygen from the air and release carbon dioxide is called respiration. Respiration is a continuous process.

Q(xiv). Give equation of respiration.

Ans: Glucose + oxygen ⟶ carbon dioxide + water + energy

Q(xv). Gasses exchange in leaves how many step?

Ans: Exchange of gasses in leaves takes place in two steps.

1- Photosynthesis 

2- Respiration

Q(xvi). How photosynthesis occur during daytime?

Ans: During photosynthesis plants produce glucose and oxygen. They use glucose and oxygen in respiration, while carbon dioxide and water produced. These products are used in photosynthesis.

Q(xvii). How photosynthesis happens during night time?

Ans: At night time, the process of photosynthesis stops but respiration is a continuous process plants take in oxygen from the air and give out carbon dioxide and water in respiration.

Q(xviii). Compare photosynthesis and respiration?

Ans: 

Photosynthesis	Respiration
Occurs in plants Food making process Traps energy to produce glucose	Occurs in living organisms Food using process Break glucose to release energy

Q(xix). Why we not sleep under trees in night time?

Ans: It is a advised not to sleep under a tree during night. Because high amount of carbon dioxide and less oxygen in the air.

Class 6 Science Notes, Class 6 Science unit-3 Notes, 

Class 6 G.Sc Notes

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