Lakhmir Singh & Manjit Kaur: How do Organisms Reproduce?, Solutions- 1

Page No - 141

Question 1:
Which life process ensures that a plant or animal species will not disappear from this earth ?
Solution :
Reproduction. 

Question 1:
Which life process ensures that a plant or animal species will not disappear from this earth ?
Ans: Reproduction. Reproduction is the biological process by which organisms produce new individuals; it ensures continuity of species on Earth.

Question 2:
What is the name of the reproductive process :
(a) which involves two parents ?
(b) which involves only one parent ?
Solution :
(a) Sexual reproduction.
(b) Asexual reproduction.

Question 2:
What is the name of the reproductive process :
(a) which involves two parents ?
(b) which involves only one parent ?
Ans:
(a) Sexual reproduction - This involves two parents and the fusion of male and female gametes.
(b) Asexual reproduction - This involves a single parent and does not use gametes.

Question 3:
State whether the following statement is true or false :
Spores produced by the bread mould plant are actually its seeds.
Solution :
False.

Question 3:
State whether the following statement is true or false :
Spores produced by the bread mould plant are actually its seeds.
Ans: False.
Explanation: Spores are single-celled reproductive units produced by fungi such as bread mould (Rhizopus). They are different from seeds, which are multicellular structures produced by flowering plants and contain an embryo and stored food.

Question 4:
Most of the plants reproduce by sexual method. Name two plants which can reproduce asexually.
Solution :
Ferns and mosses.

Question 4:
Most of the plants reproduce by sexual method. Name two plants which can reproduce asexually.
Ans: Ferns and mosses. Both these plants commonly produce spores and can reproduce without seeds or flowers.

Question 5:
Which type of reproduction :
(a) involves gametes ? .
(b) does not involve gametes ?
Solution :
(a) Sexual reproduction.
(b) Asexual reproduction.

Question 5:
Which type of reproduction :
(a) involves gametes ? .
(b) does not involve gametes ?
Ans:
(a) Sexual reproduction - involves male and female gametes.
(b) Asexual reproduction - does not involve gametes; a single parent produces offspring.

Question 6:
State whether human beings reproduce by sexual method or asexual method.
Solution :
Sexual method.

Question 6:
State whether human beings reproduce by sexual method or asexual method.
Ans: Sexual method. Human reproduction involves the fusion of male and female gametes (sperm and ovum) from two parents.

Question 7:
(a) Name two animals which reproduce sexually.
(b) Name two animals which reproduce asexually.
Solution :
(a) Dogs and cows.
(b) Amoeba and Hydra.

Question 7:
(a) Name two animals which reproduce sexually.
(b) Name two animals which reproduce asexually.
Ans:
(a) Dogs and cows - both reproduce by sexual reproduction involving two parents.
(b) Amoeba and Hydra - Amoeba reproduces by binary fission and Hydra commonly reproduces by budding (both are asexual methods).

Question 8:
Name one organism which reproduces by spore formation.'
Solution :
Bread mould (Rhizopus fungus).

Question 8:
Name one organism which reproduces by spore formation.'
Ans: Bread mould (Rhizopus). Rhizopus produces spores (sporangiospores) which help it to reproduce and spread.

Question 9:
Name the method by which Paramecium reproduces. Is this method sexual or asexual ?
Solution :
Binary fission; Asexual method.

Question 9:
Name the method by which Paramecium reproduces. Is this method sexual or asexual ?
Ans: Paramecium reproduces by binary fission, which is an asexual method. In binary fission the cell splits into two daughter cells, each developing into a new individual.

Question 10:
Name two plants :
(a) which can be grown from their broken stems.
(b) which can be grown from their leaves.
Solution :
(a) Bryophyllum and money plant.
(b) Bryophyllum and Begonia

Question 10:
Name two plants :
(a) which can be grown from their broken stems.
(b) which can be grown from their leaves.
Ans:
(a) Bryophyllum and money plant - both can grow from stem pieces or stem cuttings.
(b) Bryophyllum and Begonia - Bryophyllum produces plantlets on its leaf margins and Begonia can be grown from leaf cuttings.

Question 11:
Name the asexual method of reproduction in yeast.
Solution :
Budding.

Question 11:
Name the asexual method of reproduction in yeast.
Ans: Budding. In yeast a small outgrowth (bud) forms on the parent cell, grows and then detaches to become a new individual.

Question 12:
Name the asexual method of reproduction in (a) Hydra, and (b) Plasmodium.
Solution :
(a) Budding and regeneration. (b) Multiple fission.

Question 12:
Name the asexual method of reproduction in (a) Hydra, and (b) Plasmodium.
Ans:
(a) Hydra - Budding (and it can also regenerate lost parts).
(b) Plasmodium - Multiple fission (one cell divides into many daughter cells).

Question 13:
What is the name of asexual reproduction method in :
(i) Spirogyra, and (ii) Leishmania ?
Solution :
(i) Fragmentation.
(ii) Binary fission.

Question 13:
What is the name of asexual reproduction method in :
(i) Spirogyra, and (ii) Leishmania ?
Ans:
(i) Spirogyra - Fragmentation, where the filament breaks into pieces and each piece grows into a new filament.
(ii) Leishmania - Binary fission, where a cell divides into two similar daughter cells.

Question 14:
Name the artificial propagation mehod used for the propagation of (a) rose plants, and (b) apple trees.
Solution :
(a) Cutting.
(b) Grafting.

Question 14:
Name the artificial propagation mehod used for the propagation of (a) rose plants, and (b) apple trees.
Ans:
(a) Rose - Cutting: a piece of stem is rooted to form a new plant.
(b) Apple - Grafting: a desired variety is joined onto a rootstock to grow as one plant.

Question 15:
Which artificial propagation method is used for the production of jasmine plants ?
Solution :
Layering.

Question 15:
Which artificial propagation method is used for the production of jasmine plants ?
Ans: Layering. In layering a stem is bent to the ground and covered with soil so it forms roots and gives rise to a new plant.

Question 16:
Name the natural method by which strawberry plants are propagated.
Solution :
Layering.

Question 16:
Name the natural method by which strawberry plants are propagated.
Ans: Layering (by runners). Strawberry plants send out horizontal stems (runners) that form new plantlets at nodes which root and grow independently.

Question 17:
Name two plants which are propagated by layering method.
Solution :
Hibiscus and Bougainvillea.

Question 17:
Name two plants which are propagated by layering method.
Ans: Hibiscus and Bougainvillea. Both can produce roots from stems that are bent to the ground and then form new plants.

Question 18:
Name any two plants which are propagated by cuttings method.
Solution :
Rose and grapes.

Question 18:
Name any two plants which are propagated by cuttings method.
Ans: Rose and grapes. Stem cuttings of these plants can be rooted to produce new, true-to-type plants.

Question 19:
Write down the different methods of asexual reproduction.
Solution :
The different methods of asexual reproduction are:(i) Fission(ii) Budding.(iii) Spore formation.(iv) Regeneration.(v) Fragmentation.(vi) Vegetative propagation.

Question 19:
Write down the different methods of asexual reproduction.
Ans: The different methods of asexual reproduction are:
(i) Fission - a cell divides into two (e.g., Amoeba).
(ii) Budding - a new individual grows from a bud (e.g., Hydra, yeast).
(iii) Spore formation - spores are produced (e.g., fungi, ferns).
(iv) Regeneration - a whole organism grows from a part (e.g., Planaria, Hydra).
(v) Fragmentation - a filament breaks into pieces that grow into new individuals (e.g., Spirogyra).
(vi) Vegetative propagation - new plants grow from roots, stems or leaves (e.g., potato tubers, Bryophyllum).

Question 20:
Why are budding, fragmentation and regeneration, all considered to be asexual type of reproduction ?
Solution :
Because all these methods involves a single parent for the production of a new organism, without the involvement of gametes.

Question 20:
Why are budding, fragmentation and regeneration, all considered to be asexual type of reproduction ?
Ans: These methods are asexual because a single parent produces offspring without the fusion of gametes. The new individuals arise from part of the parent and are genetically similar to it.

Question 21:
Fill in the following blanks with suitable words :
(a) The process of.........ensures continuity of life on earth.
(b) Plasmodium reproduces by the process of........fission whereas Paramecium reproduces by the process
of..........fission.
(c) Rose plants and sugar cane crop are usually grown by the...........method.
(d) Vegetative reproduction of potato plants is done by using...........
(e) Strawberry plants are propagated by the natural...........method.
Solution :
(a) Reproduction.
(b) Multiple; Binary.
(c) Cutting.
(d) Tubers.
(e) Layering.

Question 21:
Fill in the following blanks with suitable words :
(a) The process of.........ensures continuity of life on earth.
(b) Plasmodium reproduces by the process of........fission whereas Paramecium reproduces by the process
of..........fission.
(c) Rose plants and sugar cane crop are usually grown by the...........method.
(d) Vegetative reproduction of potato plants is done by using...........
(e) Strawberry plants are propagated by the natural...........method.
Ans:
(a) Reproduction.
(b) Multiple; Binary.
(c) Cutting.
(d) Tubers.
(e) Layering.

Question 22:
a) What is the basic difference between asexual reproduction and sexual reproduction ?
(b) Which of the following organisms reproduce by sexual method and which by asexual method ?
Amoeba, Cats, Humans, Hydra, Birds
Solution :
(a)
Asexual Reproduction
(i) The offspring arises from a single parent.
(ii) The production of new organism does not involve gametes
Example:- Amoeba, Yeast.
Sexual Reproduction
(i) The offspring arises from two parents of different sexes.
(ii) The production of new organisms involves the use of gametes.
Example:- Fish, Frogs, etc.
(b)
(i) Sexual Method: Cats, Humans, birds.
(ii) Asexual method: Amoeba, Hydra.

Question 22:
a) What is the basic difference between asexual reproduction and sexual reproduction ?
(b) Which of the following organisms reproduce by sexual method and which by asexual method ?
Amoeba, Cats, Humans, Hydra, Birds
Ans:
(a) Basic differences:
Asexual reproduction - Offspring arises from a single parent; gametes are not involved; offspring are usually genetically identical to the parent (examples: Amoeba, yeast).
Sexual reproduction - Offspring arise from two parents of different sexes; it involves fusion of gametes (examples: humans, cats, birds).
(b) Classification:
Sexual method: Cats, Humans, Birds.
Asexual method: Amoeba, Hydra.

Question 23:
(a) What is meant by regeneration ? Name two animals which can regenerate fully from their cut body
parts.
(b) Explain why, more complex multicellular organisms cannot give rise to new organisms through regeneration.
Solution :
(a) The process of getting back a full organism from its body parts is called regeneration. The two animals which can regenerate fully from the cut body parts are ? Planaria and Hydra.(b)In complex multicellular organisms, specialized cells makeup tissues; tissues makeup organs; organs makeup organs systems and finally organs systems makeup organisms. Since complex Multi cellular organisms have a high degree of organisation in their body, they cannot be reproduced from their cut body parts by the process of regeneration.

Question 23:
(a) What is meant by regeneration ? Name two animals which can regenerate fully from their cut body
parts.
(b) Explain why, more complex multicellular organisms cannot give rise to new organisms through regeneration.
Ans:
(a) Regeneration is the process by which an organism regrows lost or damaged body parts and, in some cases, a whole organism can be formed from a part. Examples of animals that can regenerate fully from cut parts are Planaria and Hydra.
(b) More complex multicellular organisms cannot usually give rise to new organisms by regeneration because their bodies have a high degree of specialised tissues and organs arranged into organ systems. A cut part lacks the full set of specialised structures and coordinated organisation needed to develop into a whole organism.

Question 24:
Explain vegetative propagation with the help of two examples. List two advantages of vegetative propagation.
Solution :
In vegetative propagation, new plants are obtained from the parts of old plants (stems, roots and leaves), without the help of reproductive organs. Example ? Bryophyllum plant reproduces from its leaves and money plant grows from its stem. Advantages of vegetative propagation:- (i) Plants grow faster by the process of vegetative propagation. (ii) They need less care.

Question 24:
Explain vegetative propagation with the help of two examples. List two advantages of vegetative propagation.
Ans: Vegetative propagation is a type of asexual reproduction in plants in which new plants arise from vegetative parts such as stems, roots or leaves, without seeds or flowers.
Examples:
- Bryophyllum - produces small plantlets on the margins of its leaves; these plantlets fall off and grow into new plants.
- Money plant - can be grown from stem cuttings that develop roots and form new plants.
Advantages:
1. Plants grow faster and start giving flowers or fruits sooner than from seeds.
2. The new plants are true-to-type (genetically identical) to the parent and usually need less care to establish.

Question 25:
(a) What is meant by the term 'artificial propagation of plants' ?
(b) Name three common methods which are used for the artificial propagation of plants.
(c) Name two plants which are usually propagated by artificial propagation methods. Name the method of artificial propagation used in each case.
Solution :
(a) The process of growing many plants from one plant by man-made methods is called artificial propagation of plants. (b) The methods used for artificial propagation of plants are:
(i) Cutting
(ii) Layering and
(iii) Grafting
(c)
(i) Rose grows by means of cutting.
(ii) Jasmine grows by layering

Question 25:
(a) What is meant by the term 'artificial propagation of plants' ?
(b) Name three common methods which are used for the artificial propagation of plants.
(c) Name two plants which are usually propagated by artificial propagation methods. Name the method of artificial propagation used in each case.
Ans:
(a) Artificial propagation of plants is the human-guided process of producing many plants from a single parent plant using special techniques.
(b) Common methods: Cutting, Layering and Grafting.
(c) Examples:
- Rose - Cutting.
- Jasmine - Layering.