Class-7, Science, Chapter:- 1 Nutrition In Plants Notes, NCERT Solutions & Frequently Asked Questions
Science
Class:-7, Chapter:- 1
Nutrition In Plants
Notes, NCERT Solutions & Frequently Asked Questions
-- Notes --
⭐ Nutrition:- It is the mode of taking food by an Organisms & it's utilisation by body.
⭐ Nutrients:- The components of food such as carbohydrates, fats, vitamins & minerals are called nutrients & these give our nutrition to our body.
• All creatures consume food and use it to obtain energy for body growth and upkeep.
⭐ Autotrophic Nutrition:- The mode of nutrition in which make food from simple substances (water & carbon dioxide), at their own, is called autotrophic nutrition.
• Plants & animals that follows auttorophic nutrition are called autotrophs.
• Eg.- plants, some algae
⭐ Heterotrophic Nutrition:- The mode of nutrition in which one depends on other organisms/plants for their food, is called Heterotrophic nutrition.
• Plants or animals that follows Heterotrophic nutrition are called Heterotrophs.
• Eg.- Humans, Tigers, Lions etc.
⭐ Saprotrophic Nutrition:- The mode of nutrition in which organisms take in nutrients from dead & decaying matter is called Saprotrophic nutrition.
• Organisms following saprotrophic nutrition are called saprotrophs.
• Eg.- mushrooms, molds, and some fungi and bacteria etc.
• Fungi can also grow on pickles, leather clothes & other things if left in hot & humid environment for long time.
• Fungal spores are generally present in air. When they land on wet & warm things, they germinate & grow.
⭐ Cells:- Body of living organisms is made up of tiny structural & functional units called cells.
⭐ Cell Membrane:- The thin outer boundary in which cells are enclosed is called cell membrane.
⭐ Nucleus:- Most cells have a distinct, spherical structure in their centre which is called nucleus.
⭐ Cytoplasm:- The nucleus is surrounded by a jelly-like substance called cytoplasm.
⭐ Stomata:- There are several tiny spores present on the surface of leaves for gaseous exchange, called stomata.
• Stomata are surrounded by gaurd cells which controls the opening & closing of stomata.
⭐ Chlorophyll:- The leaves have a green pigment called chlorophyll which helps leaves to capture sunlight.
⭐ Photosynthesis:- It is the process of synthesis of food by green plants.
• It takes place in the leaves .
• It requires chlorophyll, sunlight, carbon dioxide and water.
• Carbon dioxide is taken in through stomata.
• Water and minerals are transported to the leaves from the roots through the stem.
• Chlorophyll helps the leaves use the energy from the sunlight to prepare food using the carbon dioxide, water and minerals.
• Oxygen is released in this process.
• Photosynthesis also takes place in green stems & branches.
• Presence of starch in leaves indicates the occurrence of photosynthesis.
⭐ Algae:- The slimy, green patches in water bodies are formed by the growth of an organism called algae.
• These also contain chlorophyll, which give them green colour & these can make their own food.
• Carbohydrates are used to make other food components such as proteins & fats.
• Proteins are made from nitrogen.
⭐ Parasites:- Organisms & plants that live on the body of other organisms/plants & take their nutrition from their body are called parasites.
• Eg.- Cascuta (amarbel), lice etc.
⭐ Insectivorous Plants:- Green plants that get their nutrition from both the environment & by eating small insects.
• Eg.- Pitcher plant, bladderwort, and Venus flytrap.
⭐ Symbiosis:- It is a type of nutrition in which two or more individuals work & live together to meet their nutritional needs.
• Eg.- Certain fungi live inside the roots of plants. The plant provide nutrients to fungus & in return fungus provide water & certain nutrients.
• Lichens are a complex life form that is a symbiotic partnership of two separate organisms, a fungus and an alga. The dominant partner is the fungus.
• The fungus provides a structure for the algae to live in, while the algae provides food for the fungus.
• Crops require a lot of nitrogen to make proteins but they can not use the nitrogen gas available in the atmosphere directly.
• Rhizobium bacteria live in the root nodules of leguminous plants. These bacteria take nitrogen gas from the atmosphere & convert it into water-soluble nitrogen compounds making it available to the leguminous plants for their growth.
• In return, leguminous plants provide food and shelter to the bacteria as Rhizobium cannot prepare its food. They, thus have a symbiotic relationship.
• This association is very important for the farmers, as they do not need to add nitrogen fertilisers to the soil in which leguminous plants are grown.
Exercise Questions
1. Why do organisms take food?
Solution:- All organisms require energy for their life processes. Plants prepare their food and acquire nutrients from abiotic components like soil, air, water and sunlight. On the other hand, animals need to get food from either plants or other animals to obtain nutrients; hence, animals need to take food to acquire nutrients and energy.
2. Distinguish between a parasite and a saprophyte.
Solution:
3. How would you test the presence of starch in leaves?
Solution:- Take two potted plants of the same kind. Keep one in the dark for 72 hours and the other in the sunlight. Perform the iodine test with the leaves of both plants as given below. Now, leave the pot, which was earlier kept in the dark, undisturbed for 3–4 days and perform the iodine test again on its leaves.
Iodine test:- Put iodine solution on the leaf.
Observation:- Blue-black colour will be observed on the leaves of the plant kept in sunlight, which indicates the presence of starch.
Blue-black colour will not be observed on the leaves of plants kept in the darkroom. This indicates the absence of starch.
4. Give a brief description of the process of synthesis of food in green plants.
Solution:- Green plants use a process called photosynthesis to prepare their food. The process is as follows
- Water is taken from the roots of the plant, and it is transported to the leaves of the plant.
- Carbon dioxide from the air enters the leaves through pores called stomata. This diffuses the cell containing chlorophyll.
- Water molecule is broken down into Hydrogen and Oxygen with the help of sunlight.
- Hydrogen combines with Oxygen and Hydrogen to form carbohydrates.
- Photosynthesis is represented by the following equation.
5. Show with the help of a sketch that plants are the ultimate source of food.
Solution:-
6. Fill in the blanks.
(a) Green plants are called _________________ since they synthesise their own food.
(b) The food synthesised by plants is stored as _________________.
(c) In photosynthesis, solar energy is absorbed by the pigment called ___________.
(d) During photosynthesis, plants take in ______________________ and release __________________ gas.
Solution:- a) autotrophs b) starch c) chlorophyll d) carbon dioxide & oxygen
7. Name the following.
i) A parasitic plant with a yellow, slender and branched stem.
ii) A plant that is partially autotrophic.
iii) The pores through which leaves exchange gases.
Solution:- i) Cuscuta ii) Pitcher plant iii) Stomata
8. Tick the correct answer.
a) Cuscuta is an example of:
i) autotroph ii) parasite iii) saprotroph iv) host
b) The plant which traps and feeds on insects is:
i) Cuscuta ii) China rose iii) pitcher plant iv) rose
Solution:- a) (ii) Parasite b) (iii) pitcher plant
9. Match the items given in Column I with those in Column II.
Solution:-
10. Mark ‘T’ if the statement is true and ‘F’ if it is false.
(i) Carbon dioxide is released during photosynthesis. (T/F)
(ii) Plants which synthesise their food are called saprotrophs. (T/F)
(iii) The product of photosynthesis is not a protein. (T/F)
(iv) Solar energy is converted into chemical energy during photosynthesis. (T/F)
Solution:-
- False
- False
- True
- True
11. Choose the correct option from the following:
Which part of the plant takes in carbon dioxide from the air for photosynthesis?
(i) Root hair (ii) Stomata (iii) Leaf veins (iv) Petals
Solution:
The answer is (ii) Stomata
12. Choose the correct option from the following:
Plants take carbon dioxide from the atmosphere mainly through their:
(i) roots (ii) stem (iii) flowers (iv) leaves
Solution:
The answer is (iv) leaves
13. Why do farmers grow many fruits and vegetable crops inside large greenhouses? What are the advantages to the farmers?
Solution:
Fruits and vegetable crops are grown in large greenhouses because it protects crops from external climatic conditions and provides suitable temperature for the growth of crops.
Advantages to farmers while growing fruits and vegetable crops inside greenhouses are
- It protects crops from diseases and adverse climatic conditions.
- It protects crops from wind and rodents
- By Durgesh Pandey
Eklavya Coaching Institute
H-2/25, Gali No-23, Kunwar Singh Nagar, Nangloi, New Delhi-110041
Contact No.- 8376976688
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