Thursday, 30 June 2011

Chapter 12. Reproduction in Plants: CBSE NCERT Class VII (7th) Science

 Exercises : Solution | Questions & Answers

1.Question :  Fill in the blanks:
(a) Production of new individuals from the vegetative part of parent is called  reproduction.
(b) A flower may have either male or female reproductive parts. Such a flower is called unisexual flowers.
(c) The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as pollination.
(d) The fusion of male and female gametes is termed as  fertilisation.
(e) Seed dispersal takes place by means of  windwater and animals



2.Question:  Describe the different methods of asexual reproduction. Give examples.
Answer : In asexual reproduction new plants are without production of seeds or   spores.
The main  methods of   asexual reproduction  are :            
  1. Fragmentation :In ponds, or in other stagnant water bodies, the algae which looks like slimy green patches over the water surface, use asexual reproduction for its growth . When water and nutrients are available algae grow and multiply rapidly by fragmentation. An alga breaks up into two or more fragments. These fragments or pieces grow into new individuals. This process continues and they cover a large area in a short period of time.
  2. Budding : Tiny organisms like yeast which can be seen only under a microscope, grow and multiply every few hours if sufficient nutrients are made available to them. The yeast is a single-celled organism.The small bulb-like projection coming out from the yeast cell is called a bud. The bud gradually grows and gets detached from the parent cell and forms a new yeast cell. The new yeast cell grows, matures and produces more yeast cells. If this process continues, a large number of yeast cells are produced in a short time.
  3. Spore formation :The spores are asexual reproductive bodies. Each spore is covered by a hard protective coat to withstand unfavourable conditions such as high temperature and low humidity. So they can survive for a long time. Under favourable conditions, a spore germinates and develops into a new individual. Examples : Plants such as fungi, moss and ferns  also reproduce by means of spores.
  4. Vegetative propagation.: It is a type of asexual reproduction in which new plants are produced from
    roots, stems, leaves and buds. Since reproduction is through the vegetative parts of the plant, it is known as vegetative propagation.The plants like rose or champa can be propagated through Vegetative propagation.
3. Question: Explain what you understand by sexual reproduction.
Answer : In sexual reproduction, new plants are obtained from seeds.The flowers are the reproductive parts of a plant.The stamens are the male reproductive part and the pistil is the female reproductive part. A pistil consists of stigma, style and ovary. The ovary contains one or more ovules. The transfer of pollen from the anther to the stigma of a flower is called pollination.The female gamete or the egg is formed in an ovule . In sexual reproduction a male and a female gamete fuse to form a zygote.The process of fusion of male and female gametes (to form a zygote) is called fertilisation . The zygote develops into an embryo.After fertilisation, the ovary grows into a fruit and other parts of the flower fall off. The fruit is the ripened ovary. The seeds develop from the ovules. The seed contains an embryo enclosed in a protective seed coat.Seeds and fruits of plants are carried away by wind, water and animals and reproduced again on the grounds.

4. Question: State the main difference between asexual and sexual reproduction.
Answer : In asexual reproduction plants can give rise to new plants without seeds, whereas in sexual
reproduction, new plants are obtained from seeds.

5. Question: Sketch the reproductive parts of a flower.
Answer :

6.Question:  Explain the difference between self-pollination and cross-pollination.
Answer :
Pollination is of two types, self-pollination and cross-pollination. In self-pollination, pollen grains are transferred from the anther to the stigma of the same flower. In cross-pollination, pollen grains are transferred from the anther of one flower to the stigma of another flower of the same kind.
Self Pollination and Cross Pollination

7. Question:  How does the process of fertilisation take place in flowers?
Answer : The flowers are the reproductive parts of a plant.The stamens are the male reproductive part and the pistil is the female reproductive part. A pistil consists of stigma, style and ovary. The ovary contains one or more ovules. The transfer of pollen from the anther to the stigma of a flower is called pollination.The female gamete or the egg is formed in an ovule The process of fusion of male and female gametes (to form a zygote) in flowers is called fertilisation . The zygote develops into an embryo.After fertilisation, the ovary grows into a fruit and other parts of the flower fall off. The fruit is the ripened ovary. The seeds develop from the ovules. The seed contains an embryo enclosed in a protective seed coat.Seeds and fruits of plants are carried away by wind, water and animals and reproduced again on the grounds.
8. Question: Describe the various ways by which seeds are dispersed.
Answer : Seed are dispersed by wind, water and animals.
Winged seeds such as those of drumstick and maple, light seeds of grasses or hairy seeds of aak (Madar) and hairy fruit of sunflower, get blown off with the wind to far away places. Some seeds are dispersed by water. These fruits or seeds usually develop floating ability in the form of spongy or fibrous outer coat as in coconut. Some seeds are dispersed by animals, especially spiny seeds with hooks which get attached to the bodies of animals and are carried to distant places. Examples are Xanthium  and Urena.Some seeds are dispersed when the fruits burst with sudden jerks. The seeds are scattered far from the parent plant.This happens in the case of castor and balsam.

9. Question: Match items in Column I with those in Column II:
Column I                       Column II
(a) Bud                         (i) Maple
(b) Eyes                       (ii) Spirogyra
(c) Fragmentation         (iii) Yeast
(d) Wings                     (iv) Bread mould
(e) Spores                    (v) Potato
                                    (vi) Rose
Answer :

Column I                     Column II

(a) Bud                       (iii) Yeast
(b) Eyes                     (v) Potato
(c) Fragmentation.      (ii) Spirogyra
(d) Wings                   (i) Maple
(e) Spores                 (iv) Bread mould
              

10.Question :  Tick (\/) the correct answer:
(a) The reproductive part of a plant is the
(i) leaf (ii) stem (iii) root (iv) flower
Answer :  The reproductive part of a plant is the --- (iv) flower

(b) The process of fusion of the male and the female gametes is called
(i) fertilisation (ii) pollination (iii) reproduction (iv) seed formation
Answer : The process of fusion of the male and the female gametes is called -- (i) fertilisation

(c)  Mature ovary forms the
(i) seed  (ii) stamen  (iii) pistil  (iv) fruit
Answer :  Mature ovary forms the - (iv) fruit

(d) A spore producing plant is
(i) rose   (ii) bread mould    (iii) potato    (iv) ginger
Answer : A spore producing plant is --- (ii) bread mould

(e) Bryophyllum can reproduce by its
(i) stem   (ii) leaves   (iii) roots   (iv) flower
Answer : Bryophyllum can reproduce by its --(ii) leaves

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Extended Learning—Activities and Projects
1. Make your own cactus garden by collecting pieces cut from different kinds of cacti. Grow the variety in one single flat container or in separate pots.

2. Visit a fruit market and collect as many local fruits as possible. If many fruits are not available, you can collect tomatoes and cucumbers (these are fruits, though we use them as vegetables). Make drawings of the different fruits. Split the fruits and examine the seeds within. Look for any special characteristics in the fruits and their seeds. If possible visit the website:
www.saps.plantsci.cam.ac.uk/fscfruit/dispersal.pdf
You can visit a library also to learn about this.

3. Think of ten different fruit-bearing plants. Remember that many vegetables are also fruits of the plants. Discuss with your teacher, parents, farmers, fruit growers and agricultural experts (if available nearby) and find out the manner of their dispersal. Present your data in the form of a table as shown below:
..............  ..................
4. Suppose there is one member of a particular kind of organism in a culture dish, which doubles itself in one hour through asexual reproduction. Work out the number of members of that kind of organism which will be present in the culture dish after ten hours. Such a colony of individuals arising from one parent is called a “clone”.
You can read more on the following website:
www.edumedia-sciences.com/a437_l2-blog-call.html
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Chapter 12. Reproduction in Plants: CBSE NCERT  Class VII (7th) Science

7 comments:

  1. Good, now there is no need to buy costly guides.
    this is the best online guide.
    -Shubham Modi

    ReplyDelete
  2. How is bread mould a plant??? And why does it produce spores???

    ReplyDelete
    Replies
    1. spores are tiny cells protected by a thick wall, which helps them to survive under unfavorable conditions. The fact that spores are small and light makes it easy to float in air. When it lands on an area where it gets right amount of food, warmth and moisture, it grows into a new indidvisual. Eg- mushrooms, mould, Fungi; plants such as moss, fern.

      Delete
  3. dis z superb....
    no need of guides...

    ReplyDelete
  4. good but check out ur spellings :p

    ReplyDelete