These TS 7th Class Science Important Questions 13th Lesson Seed Dispersal will help the students to improve their time and approach.
TS 7th Class Science Important Questions 13th Lesson Seed Dispersal
Question 1.
Often we see the growth of plants in the cracks or crevices of walls and stones. How did seeds reach there?
Answer:
- Seeds are carried from one place to the other. This is called seed dispersal.
- Seed dispersal is done by wind, water, birds and animals.
- Birds carry the seeds with their beaks. Some of them fall while they eat them on the walls and stones.
- If the seeds enter into crevices or cracks of the walls and stones, with enough moisture they grow into plants.
Question 2.
What is seed dispersal ? What are the possible ways of seed dispersal?
Answer:
Seeds are carried from one place to another so that they get suitable conditions to grow. This is called dispersal of seeds. Dispersal of seeds is done by the following ways.
- Seed dispersal by wind
- Seed dispersal by water
- Seed dispersal by birds
- Seed dispersal by animals
- Seed dispersal by other ways
- Seed dispersal by bursting of fruits
Question 3.
Read the following.
A. Dandelion, maple, neem, lotus, achyranthus, grass plant seeds, balsam, bhendi, guava, tomato, wheat, pulses, thorn apple, cucumber.
Classify the above plant seeds of dispersal with the help of table given below.
| S. No | Way of dispersal | Plant seed |
| 1. | By wind | Dandelion, maple, grass plant seeds |
| 2. | By water | Lotus |
| 3. | By birds | Achyranthus, neem, thorn apple, cucumber |
| 4. | By animals | Guava, tomato, cucumber |
| 5. | By bursting | Balsam, bhendi |
| 6. | By other ways | Wheat, pulses |
Question 4.
Describe agents of the seed dispersal with suitable examples.
Answer:
Different agents of the seed dispersal:
a. Dispersal by wind: Seeds that are dispersed through air are usually light and are either very small or light with wings on them or some hairy structures on them. The seeds get carried away easily by wind. Eg : Caltropis, maple, cotton seeds
b. Dispersal by water: The seeds adapted to float on water are usually light. The outer covering of the seeds has empty spaces filled with air and some are fibrous with air spaces. These facilities help in seed dispersal. Eg : Coconut Seeds that are heavy usually fall to the bottom of water sources and get carried by the flow of water. Eg : Lotus seeds.
c. Dispersal by birds: Some seeds are sticky and get stuck to the beaks of birds and in course of flight they fall down at distant places. Some seeds have to pass through the guts of some birds before they germinate. Eg : Neern, cucumber, guava.
d. Dispersal by animals: Seeds are dispersed by animals in many ways. In case of fleshy fruits, the fruit is eaten by animals. Some dry fruits with specialiszed structures like hooks, thorns, hairy parts get stuck to the bodies of animals and get carried to distant places. Eg : Ahyranthus (uttareni), kanakambararn.
e. Dispersal by bursting of fruits: Some seeds grow in capsules which when touched burst and uncoil with a force in such a way that they scatter the seeds all around. Eg : Pea, mustard, bhendi.
f. Dispersal by other ways : It is funny to think that seeds also travel by aeroplanes and ships. Eg : Wheat, pulses, oats.
Question 5.
What is meant by dispersal of seeds?
(or)
Define seed dispersal.
Answer:
Seeds are carried from one place to another so that they get suitable conditions to grow. This is called dispersal of seeds.
Question 6.
What are the ways through which dispersal of seeds occur?
Answer:
Seeds are dispersed by wind, water, birds and animals.
Question 7.
What are the physical features of seeds that help in their dispersal?
Answer:
Seeds of different shapes, sizes and structures on them help in dispersal.
Question 8.
Imagine what would happen if all the mustard seeds are germinated?
Answer:
A mustard plant produces more than 10,000 seeds in its lifetime. If all the seeds germinate to grow into adult plants, think how many seeds would be produced. If this happens for a period of six years, the entire globe will be covered with mustard plants !
Question 9.
Teacher is teaching about fruits and seeds. While the topic is going on one of the students raised some questions on seed dispersal. What questions that student might have asked. Prepare them.
Answer:
The student might have asked the following questions.
- Why seeds are in different shapes?
- What is the importance of seeds?
- How seeds are dispersed?
- Which factors influence seed germination?
- Where do we find out major seed dispersal?
Question 10.
Usually students bring some fruits to eat in leisure time. What seeds are dispersed by your classmates during schooling hours. Write as per your thorough observations.
Answer:
It was observed that school going children bring seasonally available fruits. Left over fruit material along with seeds are dispersed by them in and around the school premises. It was observed that those dispersed seeds germinated and grown in those areas. Eg: Custard apple, sweet lemon, apple, sapota, orange etc.
Question 11.
Tabulate the information on the seeds like grass, poppy, bhendi, coconut, ground nut, almond. Try to collect different types of seeds like seeds with
hair, thorns, big, small, light, heavy etc.,
Answer:
Answer the questions.
1. Which seeds can be carried by air?
Answer:
Seeds of grass, poppy are carried by air.
2. Name the seeds that are round and heavy?
Answer:
Coconut seed is round and heavy.
3. Which seeds can float on water?
Answer:
Coconut seeds can float on water.
4. Which seeds contain hooks / thorns ? Why?
Answer:
No seed is thorny among the collected ones.
5. Are the hairy seeds light and flat ? Why?
Answer:
The seeds of mustard, poppy and pea are light and flat so that they can be carried away easily by wind.
6. How are fibrous seeds ? Are they light or heavy?
Answer:
Fibrous seeds like Tadi and coconut are heavy. Cotton seed is light.
7. Are there Tadi seeds in your list ? Which characteristics do you find in them?
Answer:
Tadi seed is collected. It’s shell is hard and covered by fibres.
Question 12.
Observe the animals in your surroundings. Fill in the following table.
Tabulate the information you collected on animals which contribute in seed dispersal.
Answer:
Question 13.
Write the collected information on dispersal of seeds done by man.
(or)
Form group of four or five students and try to collect information about seeds dispersed by man.
Answer:
The seeds dispersed by man are coconut, tomato, rice, cucumber, sugar cane, mango, guava, orange, lemon, sweet lemon, grapes, oats, pear, apple, banana, pomegranate, vegetables etc.
Question 14.
Collect different kinds of fruits which are available in your surroundings.
Open them and count how many seeds they have. Try to collect information about seeds and enrich the following table.
Answer:
Some fruits are collected. They were opened and the number of seeds in all the varieties of fruits are counted. The information is tabulated as given below.
Question 15.
Draw neat labelled diagrams of transverse sections of any three fruits.
Answer:
Question 16.
Why should seeds be dispersed in large number? Write the supportive answer?
Answer:
- All the seeds of a fruit should be able to germinate to produce plants.
- But this does not happen. Moreover, if all the seeds are germinated in the less available area, competition will arise. Finally no seed can grow easily. Hence they should be dispersed. Seed dispersal is essential for survival of plants.
Choose the correct answer:
Conceptual Understanding
Question 1.
The ovules are developed into …….. after fertilization.
A) fruit
B) seeds
C) ovary
D) seed coat
Answer:
B) seeds
Question 2.
The seed dispersal depends on …….
A) weight
B) shape
C) structure
D) all
Answer:
D) all
Question 3.
The seed of orchids are dispersed by
A) air
B) water
C) animals
D) man
Answer:
A) air
Question 4.
The seeds with fibres are dispersed by ( )
A) air
B) water
C) animals
D) man
Answer:
B) water
Question 5.
The seeds with parachute structures ( )
A) Caltropis
B) Coconut
C) Tadi
D) Mango
Answer:
A) Caltropis
Question 6.
The seeds dispersed by birds ( )
A) Mango
B) Neem
C) Black berry
D) Sweet potato
Answer:
B) Neem
Question 7.
The collected nuts are hidden by ( )
A) fox
B) squirrel
C) elephant
D) deer
Answer:
B) squirrel
Question 8.
The native plant which was dispersed throughout the world ( )
A) Tomato
B) Guava
C) Pear
D) Sugar cane
Answer:
D) Sugar cane
Question 9.
The factor which is not helpful for seed dispersal ( )
A) Air
B) Water
C) Temperature
D) Salinity
Answer:
D) Salinity
Question 10.
The factor for seed dispersal in mustard ( )
A) Air
B) Water
C) Birds
D) Rain
Answer:
C) Birds
II. Asking Questions and Making Hypothesis
Question 11.
If seeds have fallen in the same area, what would be the result?
A) Competition arises among the seeds for their germination
B) All the seeds grow intactly
C) Seeds die immediately
D) Seeds never germinate
Answer:
A) Competition arises among the seeds for their germination
Question 12.
Some seeds are get dispersed through animal excreta. How does it happen and what would be the possible way to happen like this?
A) eaten fruits become more strong
B) eaten seeds become more furgid
C) eaten seeds uninjured in the stomach
D) eaten seeds injured in the stomach.
Answer:
C) eaten seeds uninjured in the stomach
Question 13.
All seeds don’t germinate. It means ( )
A) some seeds never germinate
B) some seeds germinate but – die
C) some seeds germinate but plants die before maturation
D) All the above
Answer:
D) All the above
III. Experimentation and Field investigation
Question 14.
Seeds dispersed by wind in our surroundings. ( )
A) Maple
B) Lotus
C) Coconut
D) Rice
Answer:
A) Maple
Question 15.
The seeds are not dispersed by bursting of fruits. ( )
A) Peach
B) Bhendi
C) Kanakambaram
D) Balsam
Answer:
C) Kanakambaram
Question 16.
Which animal was observed for dispersal of seeds of cauliflower.
A) Donkey
B) Buffalo
C) Birds
D) Man
Answer:
D) Man
V. Communication through Drawing and Model Making
Question 17.
The given seed belongs to milk weed plant. Its dispersal is done by ( )
A) air
B) water
C) animals
D) man
Answer:
A) air
Question 18.
In the figure “bhendi”, what type of dispersal occurs? ( )
A) Dispersal by hot winds
B) Dispersal by soaking in the sand
C) Dispersal by bursting of fruit
D) Dispersal by water
Answer:
C) Dispersal by bursting of fruit
VI. Appreciation and Aesthetic Sense and Values and Application to Daily Life and Concern to Bio Diversity
Question 19.
Why plants produce a large number of seeds? ( )
A) Becuase all seeds germinate
B) Because all seeds are not germinated
C) Because no seed can ever germinate
D) All seeds are eaten up
Answer:
B) Because all seeds are not germinated
Question 20.
Seed dispersal is done not only through nature and organisms but also through machinery. What are they? ( )
A) Seeds travel by aeroplane on export and import
B) Seeds travel by ships on export and import
C) Seeds travel by vehicles on export and import
D) All the above
Answer:
D) All the above
Question 21.
Why should seeds be dispersed? ( )
A) For better place
B) For changing life of plants
C) For survival of plants
D) All the above
Answer:
D) All the above