Velammal Vidyalaya Sr Sec School - Theni

(A CBSE - IIT/NEET Integrated Sr. Sec. School)

Class: VII Ch: Nutrition in plants Subject: Biology
Mind map:
Living and Non-Living Organisms
 Living organisms like human beings, plants and animals need food to
survive and exist.
 Living organisms reproduce, respond to the environment and also adapt.
 Living organisms respire and excrete as well
Cells
Cells are tiny units that help make up a living organism. Hence they are alsocalled
building blocks of an organism.
 A cell is constituted of three major parts :
 A thin outer layer called the cell membrane.
 A spherical structure located at the centre of the cell called a nucleus.
 A jelly-like substance that surrounds a nucleus called the cytoplasm.
Nutrition
Nutrition is the mode of taking food by an organism and its utilisation by thebody.
 Nutrition is very important as the nutrients from the food consumed enablesliving
organisms to build their bodies and grow.
 Nutrition helps to repair damaged parts and organs.
 Nutrition also provides energy for carrying out various functions.
Autotrophs and Heterotrophs
Organisms that make food themselves are called autotrophs.
 Plants are an example of autotrophs as they make their own food usingcarbon
dioxide, water and light energy.
Heterotrophs;
Organisms that rely on others and usually take in ready-made food made by the
autotrophs are called heterotrophs.
 Animals and human beings are an example of heterotrophs as they dependon
plants in many ways for their food.
Photosynthesis
Photosynthesis is the process of synthesis of food by green plants.
 This process usually takes place in the leaves of plants.
 The process requires chlorophyll (green coloured
pigment), sunlight, carbon dioxide and water.
Chlorophyll
 Chlorophyll is the pigment that is responsible for the synthesis of food in green
plants.
 This pigment green colour to its bearers and is abundantly found in leaves.
 Chlorophyll is locked inside the chloroplast.
Process of Photosynthesis
The process of photosynthesis takes place in the leaves, the “food factory” of theplants.
 Carbon dioxide is taken in through tiny pores on the leaves called stomata.
 Water and minerals that are required for the process are transported to theleaves
from the roots through the stem.
 Chlorophyll helps the leaves use the energy from the sunlight to preparefood
using the carbon dioxide, water and minerals.
  Oxygen is released as a byproduct of this process.
 The equation can be given as:
Nutrients Being Replenished in Soil
Nutrients
 Plants absorb mineral nutrients from the soil in order to make their ownfood
and for other important processes.
 Soils need to be enriched with nutrients such as nitrogen, phosphorus,
potassium etc regularly.
 Only then can we grow plants and keep them healthy.
 There are 17 most important nutrients for plants.
 6 are called macronutrients and rest are called micronutrients.
 Macronutrients are required in large quantities while micronutrients are
required in very small quantities.
Other Modes of NutritionSymbiotic
Relationship
Organisms that live together and share their shelter and nutrients are said to be ina
symbiotic relationship.
 Certain fungi live in the roots of trees.
 The tree provides nutrients to the fungus and, in return, receives help fromit to
take up water and nutrients from the soil.
 This association works well for both the fungi and the tree.
 Another most common example is of Rhizobium bacteria.
 They reside in the root nodules of leguminous plants.
 The bacteria provide a plant with nitrogen that they fix and in turn, they get shelter
and food from the plant.
Rhizobium
 Rhizobium is a type of bacteria that convert atmospheric nitrogen into asoluble
form that can be utilised by plants (nitrogen fixation).
 It usually resides in the roots of leguminous plants like peas, gram, moongetc and
is instrumental in providing these plants with a rich source of nitrogen.

Parasites;
A parasite is a heterotroph that completely depends on another organism forits
food.
 The organism to which the parasite latches onto is called the host.
 The host, in the process, is deprived of all nutrients for its own growth asthey are
consumed by the parasite.
 For example, Cuscuta (Amarbel) is a nongreen plant that takes readymadefood
from the plant on which it is growing.
Saprotrophs
Organisms which rely on dead and decaying matter for their food arecalled
Saprotrophs.
 This mode of nutrition is called saprotrophic nutrition.
 For example, Fungi.
 Fungi secrete digestive juices on the dead and decaying matter and convertit into a
 solution.
 Then they absorb the nutrients from it.
Insectivorous Plants
Plants that feed on insects are called Insectivorous plants.
 These plants are green and carry out photosynthesis.
 But they grow in nitrogen-deficient soils.
 So, in order to get nitrogen, they feed on insects.
 These insectivorous plants have their parts modified for attracting and
catching insects.
 For example, The pitcher plant, Venous flytrap.

Symbiotic Relationship –
Sometimes organisms live together to share shelter and food with each other.
These are said to have a symbiotic relationship.
Examples of organisms living in a symbiotic relationship:
 Some fungi live in the roots of the trees. These fungi take food from the trees and in
return help the trees in absorbing water and nutrients from the soil.
 Sometimes an organism that contains chlorophyll such as algae lives in association
with a fungus (together called as Lichens). The algae provide food and nutrition to
the fungus while the fungus provides water, minerals and shelter to the algae

BOOK BACK EXERCISE

1. Why do organisms take

food?Ans:
 All living organisms require food to survive. It gives them energy to perform
variousactivities.
 All activities such as playing, running, walking, studying, etc. require energy. The
various components present in our food such as carbohydrates, proteins, fats,
vitamins,and minerals provide energy to our body.
 These are also important for growth and development of the body.

2. Distinguish between a parasite and a

saprotroph.Ans:
PARASITE SAPROTROPH
The organism that grows on the body of The organism that obtains nutrients from the
another organism and derives nutrients from dead or decaying organic matter is called
it is known as a parasite. saprotroph.
Examples: cuscuta and orchids Examples: fungi and some bacteria
3. How would you test the presence of starch in leaves?

 Experiment to test the presence of starch in leaves:

Take two healthy green potted plants of the same
type.
 Keep one potted plant in a dark room for one or two
daysin order to remove all the starch from the leaves.
 Keep the other plant in sunlight. Now, take one leaf from each potted plant and
put afew drops of iodine solution on them. Then note down the observation.
 No blue black colour will be observed on the leaves of the plant kept in the dark
room.This indicates the absence of starch.
 Blue black colour will be observed on the leaves of the plant kept in sunlight.
Thisindicates the presence of starch.

4. Give a brief description of the process of synthesis of food in green

plants.
Ans:
 Photosynthesis is defined as the process in
which the chlorophyll-containing plant cells
synthesise food in the form of carbohydrates,
using
carbon dioxide and water in the
presenceof solar energy.
 Sources of raw materials required
forphotosynthesis:

o Water is taken in from the roots of the plant and is transported to the
leaves.
o Carbon dioxide from the air enters the
leaves through the tiny pores called stomata and diffuses to the cells
containingchlorophyll.
o Solar energy is used to break water into hydrogen and oxygen. This
hydrogen iscombined with carbon dioxide to form food for the plants, which
is ultimately used by the animals as well.
Thus, photosynthesis can be represented by the following equation.

Carbon dioxide + water Sunlight carbohydrates+

oxygen.chlorophyll
3. Show with the help of a sketch that plants are
theultimate source of food.

Ans: Photosynthesis

4. Fill in the blanks:

Ans:
(a) Green plants are called autotrophs since they synthesise their own food.
(b) The food synthesised by the plants is stored as starch.
(c) In photosynthesis solar energy is captured by the pigment called chlorophyll.
(d) During photosynthesis, plants take in carbon dioxide and release oxygen.
3. Name the following:
Ans:
(i) A parasitic plant with yellow, slender and branched stem. - Cuscuta
(ii) A plant that is partially autotrophic. - Pitcher plant
(iii) The pores through which leaves exchange gases. - Stomata
4. Tick the correct answer:
Ans:
(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
5. Match the items given in Column I with those in Column II:
Ans:
Column I Column II
Chlorophyll Leaf
Nitrogen Bacteria
Amarbel Parasite
Animals Heterotrophs
Insects Pitcher plant
6. Mark ‘T’ if the statement is true and ‘F’ if it is false:
Ans:
(i) Carbon dioxide is released during photosynthesis. (F)
(ii) Plants which synthesise their food themselves are called saprotrophs. (F)
(iii) The product of photosynthesis is not a protein. (T)
(iv) Solar energy is converted into chemical energy during photosynthesis. (T)
7. 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
8. 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
9. Why do farmers grow many fruits and vegetable crops inside large green
houses?What are the advantages to the farmers?
Ans:
 Green house provide favourable conditions for these crops.
 Farmers get many advantages like the crops grow well. It also protects it from
highblowing wind, and rodents.