Class 7
Science
Ch 1 Nutrition in Plants
Q.1 What are nutrients? What are main nutrients?
Ans.
Nutrients:– Components of food which are necessary for our body are called nutrients.
These are carbohydrates,
proteins, fats, vitamins, minerals,Water, roughage etc.
Q.2 What do you mean by the nutrition?
Ans.
Nutrition:– The mode of
taking food and its utilising by the body by an organism is known as Nutrition.
Q.3 What do you mean by the mode of Autotrophic Nutrition?
Ans.
Autotrophic Nutrition:– The mode of
nutrition in which organisms make there food
themselves from simple substances is called autotrophic nutrition.
The animals which use the autotrophic modes of Nutrition are called autotrophs i.e. trees and plants are autotrophs.
(Autotrophic = Auto + trophic; auto = self; trophos = nourishment)
Q.4 What do you mean by the mode of Heterotrophic nutrition?
Ans.
Heterotrophic Nutrition:– The mode of nutrition in which organisms take their food from the other animates and products is called Heterotrophic Nutrition.
The animals which use the Heterotrophic modes of Nutrition are called Heterotrophs i.e. cat, dog, cow, crew, men etc are heterotrophs.
(Heterotrophs = Hetero + trophic; (Hetero = Others; trophos = nourishment)
Q.5 What do you mean by Heterotrophs and the Heterotrophic mode of nutrition?
Ans. Some plants do not have
chlorophyll so they cannot synthesise their food. They depens on the food produced by other animal and plants. i.e. like humans and animals.
Nutrition in which organisms depend upon other organisms for food to survive is called Heterotrophic mode of nutrition. Heterotrophic organisms are called Heterotrophs.
They take all the organic substances from the host to survive.
* Cuscuta (Amarbel) is a type of yellow tubular structures climbing around the stem and branches of a tree. It does not have chlorophyll so It takes readymade food from the plant on which it is climbing.
* The plant on which it climbs is called a
host. It snatches the valuable nutrients of host, so Cuscuta (Amarbel) is called a parasite.
* Mosquitoes, bed bugs, lice and leeches that suck our blood are also known as parasites.
Q.6 What do you mean by the insectivorous or carnivorous plants explain? Explain any one of insectivorous plant with diagram.
Ans. There are a few plants which can trap insects and digest them. Such insect-eating plants are called insectivorous plants. Such plants may be green or of some other colour.
Pitcher Plant :–> Pitcher Plant is insectivorous plant. It looked like a picture it is called Pitcher Plant. The leaf is the modified into a pitcher-like structure and is the modified part of the leaf and apex of the leaf forms a lid which can open and close the mouth of the pitcher.
Inside the pitcher there are many hair
in downward direction to entangled the insect. When an insect lands at the mouth of the pitcher, the lid closes and the insect slipped and gets trapped into the hair. The insect is digested by the digestive juices secreted in the pitcher.
Q.7 If the
pitcher plant is green and carries out photosynthesis, then why does it feed on insects?
Ans. Pitcher plants type plants grow in such parts of soil where soils are poor and under nutrient levels. These plants catch the insects to acquired nutrient from these sources.
These plants are insect eater plants so that they are called carnivorous plants.
Mushrooms seen fluffy
umbrella-like patches growing on rotting wood during the rainy season.
Let us find out what type of nutrients
they need to survive and from where
they get them.
Q.8 Mushrooms do not have mouths like animals, They are not like green plants as they lack chlorophyll and cannot make food by photosynthesis. How these Mushrooms acquire nutrients?
Ans. Saprotrophic Nutrition:–> These organisms are called fungi. They have a different mode of nutrition. They secrete digestive juices on the dead and decaying matter and convert it into a solution. Then they absorb the nutrients from it. This mode of nutrition in which organisms take in nutrients in solution form from dead and decaying matter is called saprotrophic nutrition.
Plants which use saprotrophic mode of nutrition are called saprotrophs. Fungi also grow on pickles, leather, clothes and other articles that are left in hot and humid weather for long time.
Q.9 Is a fungi useful or harmful to us?
Ans. Many fungi like yeast and mushrooms are useful, Some fungi are also used in medicines.
But some fungi cause diseases in plants, animals and humans. During the rainy season they spoil many things.
Q.10 Paheli is keen to know
whether her beautiful shoes, which she wore on special occasions, were spoiled by fungi during the rainy season. She wants to know how fungi appear
suddenly during the rainy season.
Ans. The fungal spores are generally
present in the air. When they land on
wet and warm things they germinate
and grow. That is why the fungi appear suddenly during the rainy season.
Now, we can figure out how we can protect our things from getting spoiled by fungi.
Q.11 What do you mean by the symbiotic relationship, explain with example ?
Ans. Symbiotic Relationship:–> Some organisms live together and share shelter and nutrients. This is called symbiotic relationship
symbiotic relationship.
* For example, in plants certain fungi live in the roots of trees. The tree provides nutrients to the fungus and, in return, receives help from it to take up water and nutrients from the soil. This association is very important for the tree.
* In organisms called lichens, lichens is an alga, a chlorophyll-containing partner and a fungus live together. The fungus provides shelter, water and minerals to the alga and, in return, the alga provides food which it prepares by photosynthesis.
Q.12 Have you seen farmers and gardeners using manure or fertilisers in the fields. Do you know why they are added to the soil?
Ans. We know that plants absorb mineral and nutrients from the soil. So, their amounts in the soil keep on declining. These nutrients need to be added from time to time to enrich the soil.
After finding out the nutrient requirement of plants we can use Fertilisers and manures to fulfill the needs of plant nutrients such as nitrogen, potassium, phosphorous, etc.
Q.13 Can a plant take nitrogen directly, if not how they got it?
Ans. Usually crops use a lot of nitrogen to make proteins. After the harvest, the soil becomes deficient in nitrogen.
Though nitrogen gas is available in
plenty in the air, but plants cannot use it directly as they can use carbon dioxide.
Q.14 Rhizobium and legumes plants have a symbiotic relationship.
Ans. Rhizobium and legumes plants have a symbiotic relationship. Legumes plants need nitrogen in a soluble form. The bacterium called Rhizobium lives in the roots of leguminous plants, It can take atmospheric nitrogen and convert it into a soluble form. But Rhizobium cannot make its own food. So it lives in the roots of leguminous plants (like gram, peas, moong, beans and other legumes).
Rhizobium provides nitrogen to plant and In return, the plants provide food and shelter to the bacteria. Most of the pulses (dals) are obtained from leguminous plants.
This association is of great significance for the farmers. They do not need to add nitrogen fertiliser to the soil in which leguminous plants are grown.
Only a few plants adopt other modes of nutrition like parasitic and saprotrophic.
Q.15 Are all animals can be categorised as heterotrophs? is carnivorous plant also heterotrophs?
Ans. Heterotrophs:–> Animals who derive nutrition from other organisms like plants and other animals.
All animals are categorised as heterotrophs since they depend on plants and other animals for food.
We can say that the insectivorous plants are partial heterotrophs?
Q.16 How the leaves or green parts of the plants synthesise their food?
Ans. During photosynthesis, chlorophyll containing cells of leaves in the presence of sunlight, use carbon dioxide and water to synthesise carbohydrates.
The process can be represented as an equation:
During the process, oxygen is released. The carbohydrates ultimately get converted into starch. The presence of starch in leaves indicates the occurrence of photosynthesis. The starch is also a carbohydrate.
Q.17 What are raw material of photosynthesis?
Ans. We know that chlorophyll,
sunlight, carbon dioxide and water are necessary to carry out the process of photosynthesis so These substances are known as raw materials for photosynthesis.
Q.18 What do you mean by the raw material of photosynthesis? from where they will get it?
Ans. Raw Materials for photosynthesis: Raw material of photosynthesis are chlorophyll, sunlight, water and carbon dioxide.
Chlorophyll is present in the leaves, Plant get sunlight from the Sun, gets water from the roots and carbon dioxide from the atmosphere through stomata.
Q.19 What is stomata?
Ans. Stomata: –> Tiny pores present on the lower surface of the leaves is called stomata. These pores are surrounded by ‘guard cells’.
Carbondioxide from air is taken
in through stomata.
Q.20 What is xylem what is its work?
Ans. Xylem:–> Water and minerals are transported
to the leaves by the vessels called xylem, which run
like pipes throughout the root, the stem, the branches and the leaves.
Q.21 What is cell? what are its main parts?
Ans. Cells:–> The bodies of living organisms are made of tiny units called cells. Cells are so tini that can be seen only under the microscope.
The cell is enclosed by a thin outer boundary, called the cell membrane.
Most cells have a distinct, centrally located
spherical structure called the nucleus.
The nucleus is surrounded by a jelly-like
substance called cytoplasm.
Q.22 What do you mean by the unicellular organism ? Give one example also.
Unicellular Organisms:–> Some organisms are made of only one cell unicellular organism i.e. amoeba.
Q.23 What are the products of photosynthesis?
Ans. Carbohydrates and oxygen are the products of photosynthesis?
Q.24 Is life is possible on the earth without photosynthesis?
Ans. Oxygen is essential for the survivalof all living organisms which is produced during photosynthesis. During the photosynthesis oxygen is released into the atmosphere.
We can see that In the absence of photosynthesis, life would be impossible on the earth.
Q.25 Besides leaves, photosynthesis also takes place in other green parts of the plant. what are they?
Ans. Besides leaves, in green stems and green branches, photosynthesis also takes place.
In the desert plants leaves have modified into the scale or spine-like leaves to reduce the loss of water by transpiration. These plants have green stems which carry out photosynthesis.
Q.26 Leaves are generally green but some leaves are red or brown in colour, are they perform photosynthesis?
Ans. Leaves are generally greens due to the presence of chlorophyll.
The leaves other than green also have
chlorophyll. The large amount of red, brown and other pigments mask the green colour. Photosynthesis takes place in these leaves also.
Q.27 We often see slimy, green patches
in ponds or in other stagnant water
bodies. What are these called? Can they synthesise their food?
Ans. We often see slimy, green patches in ponds or in other stagnant water bodies. These are generally formed by the growth of organisms called algae.
Allgae contain chlorophyll which gives them the green colour. Due to the chlorophyll algae can also prepare their own food by photosynthesis.
Q.28 What do you mean by the carbohydrates?
Ans. The
compounds made up of carbon, hydrogen and oxygen is called carbohydrates.The starch is also a carbohydrate.
In the leaves the carbohydrates ultimately get converted into starch. The presence of starch in leaves indicates the occurrence of photosynthesis.
Q.29 What do you mean by the nitrogenous compounds or nitrogenous substances?
Ans. The compounds or substances of the Nitrogen are called Nitrogenous Compounds or Nitrogenous Substances.
is compound aur substances.
Proteins are Nitrogenous Substances
which contain nitrogen. Plants also can synthesise proteins and fats.
Q.30 From where do the plants obtain nitrogen? Why did the farmers add the fertilizers in the field?
Ans. Nitrogen is a substance which is present in gaseous form in the air.
Plants cannot absorb this nitrogen directly.
Soil has certain nitrobacter bacterias that convert gaseous nitrogen into a usable form of nitrogen and release it into the soil. These soluble forms of nitrogen are absorbed by the
plants along with water.
Farmers add fertilisers rich in nitrogen to the soil to fulfil their requirements of nitrogen of the plants along with the other constituents.
Exercise
Class 7
Science
Ch. 1 Nutrition in Plants
Exercise
Q.1. Why do organisms need to take food?
Ans. Food is needed by all organisms for many purposes:
(a) The food is required in growth.
(b) Food provides energy for various works such as running, walking or raising our arm.
(c) Food is also needed to replacement or repairing the damaged parts of body.
(d) Food provides us resistance to fight against diseases and protects us from infections.
Q. 2. Distinguish between a parasite and a saprotroph
Ans.
Difference between Parasites and Saprotrophs:
Parasites Saprotrophs
A parasite derives its nutrients from the living organism and it deprives the host of valuable nutrients. For example, Mosquito.
Saprotroph organisms take in nutrients from dead and decaying matter. For example, Fungi.
Q.3. How would you test the presence of starch in leaves?
Ans. The presence of starch in leaves can be tested by Iodine test.
Process :–> Remove chlorophyll from leaf by boiling it in alcohol. Now, put 2 drops of iodine solution, on this leaf. if its colour change to blue-black. This indicates that the starch is present in the leaf.
Q.4. Give a brief description of the process of synthesis of food in green plants.
Ans. The green plants have chlorophyll in the leaves. The leaves use CO2 and water to make food in .
Q.5. Show with the help of a sketch that the plants are the ultimate source of food.
Ans.
Q.6. Fill in the blanks:
(a) Green plants are called ________________ since they synthesise their own food.
(b) The food synthesised by the plants is stored as ________________ .
(c) In photosynthesis solar energy is captured by the pigment called ________________
(d) During photosynthesis plants take in ________________ and release ________________ .
Ans.
(a) autotrophs
(b) starch
(c) chlorophyll
(d) carbon dioxide, oxygen
Q.7. Name the following:
(i) A parasitic plant with yellow, slender and tubular stem.
Ans.
(i) cuscuta
Q. (ii) A plant that has both autotrophic and heterotrophic mode of nutrition.
Ans.
(ii) Insectivorous plant
Q. (iii) The pores through which leaves exchange gases.
Ans.
(iii) Stomata
Q.8. Tick the correct answer:
(a) Amarbel is an example of:
(i) Autotroph
(ii) Parasite
(iii) Saprotroph
(iv) Host
Ans.
(a) (ii) Parasite
(b) The plant which traps and feeds on insects is:
(a) Cuscuta
(ii) China rose
(iii) Pitcher plant
(iu) Rose
Ans. (b) (iii) Pitcher plant
Q.9. Match the items given in Column I with those in Column II:
Ans.
Column 1 Column 2
Chlorophyll Leaf
Nitrogen Bacteria
Amarbel Arasite
Animal Heterotrophs
Insect. Pitcher plant
Q.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 themselves 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)
Ans.
(a) F
(ii) F
(iii) T
(iu) T
Q.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) Sepals
Ans.
(ii) Stomata
Q.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
Ans. (iv) Leaves
1 Comments
Sir yeh mujhe 3rd question samajh mein nai aaya
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