Kerala SSLC Class 9 Solutions for biology – The Sign of Life (English Medium)
Page No. 8:
What is the role played by abiotic factors in sustaining life?
- Abiotic factors help support different life forms.
- Living organisms obtain matter and energy from different abiotic factors and use them for their various life activities.
Are the features of life similar in all organisms?
There are different principal processes which occur in all living organisms – respiration, growth, response to stimuli and reproduction.
However, the mechanism of these processes is different in different organisms.
How do the features of the cell become the important sign of life?
The two key important features of a cell – metabolism and reproduction – help in sustenance of life and maintain the continuity of life.
These features help the cell to survive and maintain its population over generations.
Thus, these features of the cell are important signs of life.
Page No. 9:
Do you know what is the source of energy in the biosphere?
Solar energy from the Sun is the source of energy in the biosphere.
Why can’t the animals absorb solar energy as plants do?
Animals do not contain pigments such as chlorophyll to absorb solar energy like plants.
Page No. 10:
Will photosynthesis take place if sunlight and chlorophyll alone are present?
No, photosynthesis will not take place in the absence of raw materials such as carbon dioxide and water if sunlight and chlorophyll alone are present.
What are the raw materials needed for photosynthesis? How do they reach the leaves?
Carbon dioxide and water are the raw materials needed for photosynthesis. Carbon dioxide from the atmosphere enters leaves through stomata present on the surface. Water is obtained from the soil. It is absorbed by the roots and transported to the leaves by xylem vessels.
Examine the figure and complete the flowchart given below.
Describe the position and the structure of chloroplast.
Chloroplasts are present in the cells of leaves and tender stems. They are membrane-bound cell organelles.
Each chloroplast is covered by a double membrane. The membrane encloses a colourless ground substance called stroma. Flat, sac-like structures called thylakoids are present in the stroma. Thylakoids are arranged in pile-like stacks of coins called grana.
Name the pigment present in the chloroplast. How does it help in the absorption of light?
Chlorophyll pigment is present in the chloroplast. There are different types of chlorophyll. The major ones are chlorophyll a and chlorophyll b.
Chlorophyll a takes part directly in photosynthesis, while chlorophyll b absorbs sunlight and transfers energy to chlorophyll a.
Explain the difference between photosynthesis and chemosynthesis.
Page No. 11:
Set up the experiment as shown in the figure.
Keep this experimental set up, one hour each under the following conditions.
- In a room with little light.
- Under direct sunlight in the yard.
Did you observe the same change in the test tube when the experimental setup was placed in the room and when placed under direct sunlight?
There is a difference in the amount of gas collected in the test tubes when the experimental setup was placed in the room and when it was placed under direct sunlight.
The amount of gas produced in the experimental setup which was placed in the room was lesser than that of gas produced in the experimental setup which was placed under direct sunlight.
Lift the test tube gently above water, light a match stick and hold it against the mouth of the test tube? What happens? What is the reason for this?
Which is the gas produced?
The match stick burns more vigorously when held against the mouth of the test tube. This is because the gas collected in the test tube supports combustion. Oxygen gas is produced as a by-product of photosynthesis.
Complete the table.
|Location||Type of reaction
|Products||Necessity of Light|
Page No. 12:
We take the food which is stored by plants. Make a list of the common plant products included in our food.
Common plant products included in our food:
- Oil extracted from oil seeds
Analyse the flowchart given below and prepare a note on how the food materials we use in daily life are produced.
- Photosynthesis is the key process in plants which helps to convert solar energy from the Sun to chemical energy.
- This chemical energy is used for the synthesis of glucose.
- Glucose is then converted to different biomolecules through various processes.
- Glucose converted to starch is stored in tubers.
- Glucose converted to proteins is stored in pulses.
- Glucose converted to lipids is stored in seeds and oilseeds.
- Glucose is also stored in the form of fructose in fruits and in the form of sucrose in sugarcane.