CLASS - 7 SCIENCE (Medium- eng)

 


Chapter 1-Nutrients in Plants

NOTES


1. Components of Food – Carbohydrates, Proteins, Fats, Vitamins, Minerals.

2. Nutrients – Carbohydrates, Proteins, Fats, Vitamins, and Minerals are essential for our body, and they are called nutrients.

3. All living organisms need food.

Plants – Can make their own food.

Humans and other animals – Directly or indirectly depend on plants.

4. Nutrition – The process by which living organisms take in food and use it is called nutrition.

Autotrophic Nutrition – The method of nutrition in which organisms make their own food is called autotrophic nutrition. Therefore, such plants are called autotrophs.

Heterotrophic Nutrition – Animals and most other organisms take food synthesized by plants; they are called heterotrophs.

5. Photosynthesis Process – Leaves have tiny pores called stomata, through which carbon dioxide from the air enters. These pores are surrounded by cells.
  • Leaves contain a green pigment called chlorophyll.
  • Photosynthesis: The process by which plants make their food using chlorophyll, sunlight, carbon dioxide (CO₂), and water is called photosynthesis.

6. Algae – Green non-flowering (moss-like plants) can be seen growing on wet walls, ponds, and stagnant water bodies. These generally form due to the growth of certain organisms called algae.


7. Parasites – Some plants like Amarbel (Dodder) have chlorophyll and get their food from the plants on which they grow. The plant from which they derive food is called a host plant.
  • Parasitic plants – These plants depend on others for their nutrition and are called parasitic plants.

8. Carnivorous Plants – Some plants catch and consume insects to fulfill their nitrogen requirements.   Example: Venus flytrap and Sundew plant.

9. Saprophytic Nutrition – The process by which organisms obtain nutrition from dead and decaying organic matter is called saprophytic nutrition.
  • Organisms that use saprophytic nutrition are called saprophytes.

10. Symbiotic Relationships – Some organisms live together and share shelter and nutrients. This is called a symbiotic relationship.

11. Rhizobium – These bacteria convert atmospheric nitrogen into usable compounds. They cannot make their own food but help plants by supplying nitrogen.

                                                   EXERCISE

Question 1: Why do organisms take food?
Answer: All organisms need to take food to get energy for the growth, development and maintenance                   of their bodies.

Question 2: Distinguish between a parasite and a saprotroph.
Answer:

  • Parasites are organisms that live on or inside other living organisms and derive nutrients from them (e.g., Amarbel).
  • Saprophytes feed on dead and decaying organic matter (e.g., fungi, bacteria).

Question 3: How would you test for the presence of starch in a leaf?
Answer:

1. We can test the presence of starch by dropping iodine solution on the leave

2. When iodine solution comes into contact with starch, a deep blue color appears.

Question 4: Give a brief description of the process of synthesis of food in green plants. 
 Answer:

  1. In plants, food synthesis occurs through the process of photosynthesis.

  2. During photosynthesis, the chlorophyll-containing cells of the leaf synthesize carbohydrates from carbon dioxide and water in the presence of sunlight.

Question 5: Show with the help of a sketch that plants are the ultimate source of food. 

Answer:

vidya point

Question 6: Fill in the blanks:
a) Green plants are called _______since they synthesise.
b) The food synthesized by plants is stored as ________starch.
c) In photosynthesis solar energy is absorbed by the pigment called__________.
d) During photosynthesis plants take in________ and release_________ gas. 

Answer: a)- autotrophs, b)- starch, c)- Chlophyll, d)- carbon dioxide, oxygen.

Question 7: Name the following:
a) A parasitic plant with yellow, slender and tubular stem.
b)A plant that has both autotrophic and heterotrophic mode of nutrition. 
c)The pores through which leaves exchange gases.

Answer: a)- Cuscuta,  b)- Pitcher plant, Venus flytap,  c)- Stomata.

Question 8: Tick the correct answer: 

a)Amarbel is an exmaple of: 

1. autotroph,  2. parasite,  3. saprotroph,  4.host

b) The plant which traps and feeds on insects is: 

1. Cuscuta, 2. china rose, 3. pitcher plant, 4. rose

Answer: a)-2 Parasite,   b)- 3. Pitcher plant.

Question 9: Match the items in column A with those in column B:

COLUMN- A                                                    COLUMN- B 

Chlorophyll                                                         Bacteria

Nitrogen                                                              Heterotrophs

Amarbel                                                               Pitcher plant

Animals                                                               Leaf

Insects                                                                 Parasite

Answer:   

COLUMN- A                                                      COLUMN- B

Chlorophyll                                                            Leaf

Nitrogen                                                                 Bacteria

Amarbel                                                                 Parasite

Animals                                                                 Heterotrophs

Insects                                                                    Pitcher plant

Question 10: Mark T if the statement is true and F if it is flase:

a) Carbon dioxide is released during photosynthesis. (T/F)
b) Plants which synthesize their own food are called saprotrophs.(T/F)
c) The product of photosynthesis is not a protein. (T/F)
d) Solar energy is converted into chemical energy during photosynthesis.(T/F)

Answer: a)- False, b)- False, c)- True, d)- True.

Question 11: Choose the correct option from the following:

Which part of the plant takes in carbon dioxide from the air for photosynthesis?

a) Root hair
b) Stomata
c) Leaf veins
d) Petals
Answer: b) Stomata

Question 12: Choose the correct option from the following:

Plant take carbon dioxide from the atmosphere mainly through their: 
a) Root
b) Stem
c) Flowers
d) Leaves
Answer: d) Leaves

Question 13: Why do farmers grow many fruits and vegetables crops inside large green houses? What are the advantages to the farmers?

Answer: Greenhouses protect plants from external adverse conditions and provide the right temperature which most suitable for the plant growth. It also protects plants from diseases and adverse conditions. 

Greenhouse harvesting is booming now a days because:

  • This saves time and resources to grow plants. 
  • The plants are protected from sudden weather change by the greenhouse. 
  • Growing plants are protected from access rain fall, hail stones or stormy conditions. 
  • Plants are more productive as compared to traditional methods. 
  • It keep rats, birds and other harmful insects from plants. 


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