Class 7 Science Notes Unit # 3 Short Q/A
1. What is reproduction?
Ans: Reproduction is the process by which organisms produce more organisms like themselves. It is a basic characteristic of living things.
2. What are the male and female parts of a flower?
Ans: Carpels are the female parts of flowers. A carpel has a sticky stigma, a style and an over.
Stamens are the male parts of a flower. Each stamen has a filament, an anther and pollen grains.
3. Define sperm and egg.
Ans: A male gamete is called sperm. A female gamete is called an egg. Male and female cells fuse to form a zygote.
4. What is a zygote?
Ans: Zygote is the first cell of living organisms. Zygote developed into seed and seed grows into a new plant.
5. Differentiate between sexual and asexual reproduction.
Ans: Sexual Reproduction:
In sexual reproduction male cell (sperm) and female cell (egg) gametes take part to form a new cell called a zygote.
Asexual Reproduction: In asexual reproduction, gametes are not produced to form a new plant. Plants are grown by buds present on their stems and roots.
6. What is pollination?
Ans: The transfer of pollen grains from the anther of a flower to the stigma of the carpel is called pollination.
7. How many kinds of pollination?
Ans: There are two types of pollination:
- Self-pollination
- Cross-pollination
8. Define self-pollination.
Ans: The transfer of pollen grains from the anther to the stigma of the same flower or another flower of the same plant is called self-pollination
9. Define cross-pollination.
Ans: The transfer of the pollen grains to the stigma of a flower on another plant is called cross-pollination.
10. What are the pollinators?
Ans: The agents that carry pollen grains from the anthers of flowers to the stigmas are called pollinators.
11. What is meant by fertilization?
Ans: The process of fusion of sperm with the egg is called fertilization.
12. Which part of the seed develops into a first root?
Ans: Radicle is the part of the embryo that develops into the first root of the new plant.
13. Why is a lonely papaya tree hard to see with fruit?
Ans: The papaya plant has male and female parts on separate plants. The plant cannot bear fruit due to a lack of pollination. That’s why a lonely plant hardly produces fruit.
14. Explain the formation of seeds and fruits. Describe the structure of a seed.
Ans: After fertilization, an ovule becomes a seed. The embryo and its store of food are covered by a tough seed coat.
The most important part of a seed is its embryo. The embryo grows into a new plant. The embryo consists of the following parts.
Radicle:
This part of the embryo develops into the first root of the new plant.
Plumule:
This part of the embryo develops into the first shoot (stem) of the new plant.
Cotyledons:
This part of the embryo supplies food to the growing young plant.
15. Write a note on fruit.
Ans: The ripened ovary is called a fruit. The ovary wall forms the fruit wall, called the pericarp. Inside the ovary, ovules develop into seeds. The matured fruit may contain single or many seeds.
The pericarp has three layers in most fruits like peaches and mangoes. The outer layer is skin, the middle layer is fleshy and the inner layer is tough or hard. Some fruits have hard and dry pericarp, e.g. nuts.
16. Differentiate between self-pollination and cross-pollination.
Ans: self-pollination:
If the pollen from another falls on the stigma of the same flower, or on another flower of the same plant, this is called self-pollination.
Cross-pollination
If the pollen from the flower of one plant falls on the stigma of a flower of another plant, this is called cross-pollination.
17. Why is a butterfly attracted to a flower?
Ans: A butterfly is attracted to the flower due to its colours and fragrances. The colourful part of the flower is called the corolla.
18. Explain the possible direction for the transport of food in a plant.
Ans: Food (sugar) is transported by the phloem tissues. Phloem tissues run from leaves to every part of the plant. So, the food is transported in any direction within the plant. It may be upward and may be downward.
19. Stomata mostly occur in the lower epidermis of the leaf. How is it helpful for the plant?
Ans: Indeed, stomata are pores on leaves of green plants that allow and control the flow of liquid by transpiration. It also allows the passage of gases in and out of the plant during both respiration and photosynthesis. Air containing carbon dioxide enters the plant through these pores where it is used in photosynthesis and respiration
20. What is the role of chlorophyll in photosynthesis?
Ans: Photosynthesis is the process by which plants convert solar energy into starch to be used by plants. Chlorophyll plays a primary role in this process. Chlorophyll absorbs sunlight for photosynthesis.
21. What is the difference between autotrophs and heterotrophs?
Ans: Autotrophs:
Most plants have green leaves. They prepare food their own, these are called autotrophs. Heterotrophs:
Some plants can not make their own food due to a lack of chlorophyll. These are called heterotrophs.
22. What is the difference between parasites and saprotrophs?
Ans: Heterotrophs are of two types.
Parasites: Some plants get their food from some other living things. These are called parasites. Cuscuta (yellowish leafless threads) is an example of a parasite.
Saprotrophs: Some plants get their food from decaying dead parts of plants and animals and their wastes. Such plants are called saprotrophs. For example Monotropa.
23. What is meant by osmosis?
Ans: Movement of water molecules through a cell membrane, from a region of higher concentration of water to a region of lower concentration of water molecules, is called osmosis.
24. What is photosynthesis?
Ans: Photosynthesis is a process by which plants make their food. Chlorophyll is present in green leaves. It can absorb sunlight and convert it into chemical energy. This chemical energy is then used to combine CO2 (Carbon dioxide) and H2O (Water) to make food.
Carbon dioxide + Water (gives us) Oxygen + Glucose
25. What are insectivorous plants?
Ans: These are some plants that have modified leaves to trap the insects. These plants have chlorophyll and make their food. But these plants live in places where the soil is poor in nitrogen. They trap insects, kill them and digest them to get some nitrogen. Pitcher plant, Venus flytrap and Sundew are examples of insectivorous plants.
26. What is germination?
Ans: in suitable conditions seed starts to grow and forms a new plant. This process is called germination.
27. What is the difference between parasites and saprotrophs?
Ans: Heterotrophs are of two types.
Parasites: Some plants get their food from some other living things. These are called parasites. Cuscuta (yellowish leafless threads) is an example of a parasite.
Saprotrophs: Some plants get their food from decaying dead parts of plants and animals and their wastes. Such plants are called saprotrophs. For example Monotropa.
28. What is meant by osmosis?
Ans: Movement of water molecules through a cell membrane, from a region of higher concentration of water to a region of lower concentration of water molecules, is called osmosis.
29. What is photosynthesis?
Ans: Photosynthesis is a process by which plants make their food. Chlorophyll is present in green leaves. It can absorb sunlight and convert it into chemical energy. This chemical energy is then used to combine CO2 (Carbon dioxide) and H2O (Water) to make food.
Carbon dioxide + Water (gives us) Oxygen + Glucose
30. What are insectivorous plants?
Ans: These are some plants that have modified leaves to trap the insects. These plants have chlorophyll and make their food. But these plants live in places where the soil is poor in nitrogen. They trap insects, kill them and digest them to get some nitrogen. Pitcher plant, Venus flytrap and Sundew are examples of insectivorous plants.
31. What is germination?
Ans: in suitable conditions seed starts to grow and forms a new plant. This process is called germination.
If the pollen from another falls on the stigma of the same flower, or on another flower of the same plant, this is called self-pollination.
Cross-pollination
If the pollen from the flower of one plant falls on the stigma of a flower of another plant, this is called cross-pollination.
17. Why is a butterfly attracted to a flower?
Ans: A butterfly is attracted to the flower due to its colours and fragrances. The colourful part of the flower is called the corolla.
18. Explain the possible direction for the transport of food in a plant.
Ans: Food (sugar) is transported by the phloem tissues. Phloem tissues run from leaves to every part of the plant. So, the food is transported in any direction within the plant. It may be upward and may be downward.
19. Stomata mostly occur in the lower epidermis of the leaf. How is it helpful for the plant?
Ans: Indeed, stomata are pores on leaves of green plants that allow and control the flow of liquid by transpiration. It also allows the passage of gases in and out of the plant during both respiration and photosynthesis. Air containing carbon dioxide enters the plant through these pores where it is used in photosynthesis and respiration
20. What is the role of chlorophyll in photosynthesis?
Ans: Photosynthesis is the process by which plants convert solar energy into starch to be used by plants. Chlorophyll plays a primary role in this process. Chlorophyll absorbs sunlight for photosynthesis.
21. What is the difference between autotrophs and heterotrophs?
Ans: Autotrophs:
Most plants have green leaves. They prepare food their own, these are called autotrophs. Heterotrophs:
Some plants can not make their own food due to a lack of chlorophyll. These are called heterotrophs.
22. What is the difference between parasites and saprotrophs?
Ans: Heterotrophs are of two types.
Parasites: Some plants get their food from some other living things. These are called parasites. Cuscuta (yellowish leafless threads) is an example of a parasite.
Saprotrophs: Some plants get their food from decaying dead parts of plants and animals and their wastes. Such plants are called saprotrophs. For example Monotropa.
23. What is meant by osmosis?
Ans: Movement of water molecules through a cell membrane, from a region of higher concentration of water to a region of lower concentration of water molecules, is called osmosis.
24. What is photosynthesis?
Ans: Photosynthesis is a process by which plants make their food. Chlorophyll is present in green leaves. It can absorb sunlight and convert it into chemical energy. This chemical energy is then used to combine CO2 (Carbon dioxide) and H2O (Water) to make food.
Carbon dioxide + Water (gives us) Oxygen + Glucose
25. What are insectivorous plants?
Ans: These are some plants that have modified leaves to trap the insects. These plants have chlorophyll and make their food. But these plants live in places where the soil is poor in nitrogen. They trap insects, kill them and digest them to get some nitrogen. Pitcher plant, Venus flytrap and Sundew are examples of insectivorous plants.
26. What is germination?
Ans: in suitable conditions seed starts to grow and forms a new plant. This process is called germination.
27. What is the difference between parasites and saprotrophs?
Ans: Heterotrophs are of two types.
Parasites: Some plants get their food from some other living things. These are called parasites. Cuscuta (yellowish leafless threads) is an example of a parasite.
Saprotrophs: Some plants get their food from decaying dead parts of plants and animals and their wastes. Such plants are called saprotrophs. For example Monotropa.
28. What is meant by osmosis?
Ans: Movement of water molecules through a cell membrane, from a region of higher concentration of water to a region of lower concentration of water molecules, is called osmosis.
29. What is photosynthesis?
Ans: Photosynthesis is a process by which plants make their food. Chlorophyll is present in green leaves. It can absorb sunlight and convert it into chemical energy. This chemical energy is then used to combine CO2 (Carbon dioxide) and H2O (Water) to make food.
Carbon dioxide + Water (gives us) Oxygen + Glucose
30. What are insectivorous plants?
Ans: These are some plants that have modified leaves to trap the insects. These plants have chlorophyll and make their food. But these plants live in places where the soil is poor in nitrogen. They trap insects, kill them and digest them to get some nitrogen. Pitcher plant, Venus flytrap and Sundew are examples of insectivorous plants.
31. What is germination?
Ans: in suitable conditions seed starts to grow and forms a new plant. This process is called germination.
Encircle the correct answer in the following.
1. The movement of water molecules through a selectively permeable membrane from an area of higher concentration to an area of lower concentration is called.
(a)conduction (b)Diffusion (c)Evaporation (d)Osmosis
2. Fruit is formed from:
(a)Ovary (b) Ovule (c) Stem (d)Leaves
3. Endosperm is present in:
(a)Anther (b)Xylem (c)Stigma (d)Seed
4. Which is not part of an embryo?
(a)Pedicle (b)Plumule (c)Radicle (d)Cotyledon
5. Which statement is true for insectivorous plants?
(a) Chlorophyll is not present (b) Unable to make glucose
(c) Capture insects through roots (d) Utilize their nitrogenous needs from insects
6. Which part of the plant is called the food factory?
(a)Fruit (b)Leave (c)Root (d)Stem
7. Water moves to the upper parts of the plants through the xylem by a pull, this pull is due to the process of …………
(a)Transpiration (b)Osmosis (c)Transportation (d)Diffusion
8. The process by which water enters from the soil into the roots of the plants is called:
(a)Movement (b)diffusion (c)Transpiration (d)Transportation
9. When iodine solution is applied to starch, it turns…………….
(a)Red (b)Blue (c)Green (d)Grey
10. The network of thread-like structures in rhizopus is called………………
(a) Xylem (b) seeds (c) Hyphae (d)Threads
11. Ginger is an example of underground………………….
(a)Root (b)Root hair (c)Fibers (d)Stem
12. It is advised not to sleep under a tree during the night because of a high amount of:
(a) Oxygen (b) Carbon dioxide (c)Water vapour (d)Leaves falling
13. A flowering plant has systems.
(a)2 (b)3 (c)4 (d)5
14. It is not part of the female part of a flower.
(a)Ovary (b) Style (c) Stigma (d) filament
15. The root of the plant is formed by:
(a)Plumule (b)Tegmen (c)Cotyledons (d)Radicle