Intext Questions Solved

Page 128

Question 1 : What is the importance of DNA copying in reproduction?

Answer : Correct copying of DNA during the process of reproduction ensures correct body design. Any change in it will produce changed DNA, i.e., the blue print, that will change the synthesis of proteins and in turn the body design, i.e., it will cause variation.

Question 2 : Why is variation beneficial to the species but not necessarily for the individual?

Answer : Variation is a change in the body design of an individual . It may not be beneficial to the individual but during extreme environmental cases, it may prove to be beneficial. It reproduces and develops new species of a variant type.

Page 133

Question 1 : How does binary fission differ from multiple fission?

Answer :

Binary Fission Multiple Fission
1. When a parent cell produces two daughter cells it is called binary fission. 1. When a parent cell produces more than two daughter cells it is called multiple fission.
2. The parent nucleus divides into two and goes to two daughter cells. 2. The parent nucleus divides into many daughter nuclei each surrounded by cytoplasm.
3. It is usually during favourable conditions. 3. It is usually during unfavourable condition in other protozoans.
4. No protective covering is formed. 4 A protective covering cyst if formed.
5. It takes in different patterns as in Amoeba and Leishmania. 5. No such patterns, e.g., Plasmodium.

Question 2 : How will an organism be benefitted if it reproduces through spores?

Answer :
1. Spores are produced in large numbers. So the population will increase soon on their growth.

2. Spores have a protective coat that helps them to resist unfavourable environmental conditions that are harmful to plant.

3. Spores are carried to long distances by wind. This helps in their distribution and growth.

Question 3 : Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?

Answer : Regeneration is a simple model of reproduction in simple organisms like Hydra, Planaria, etc. They have simple body design. Complex organisms have complicated body design, systems and organs that cannot be developed by simple process of regeneration . Moreover, variations are needed for living in niche that cannot be achieved by regeneration process.

Question 4 : Why is vegetative propagation practised for growing some types of plants?

Answer : Advantages of vegetative propagation:

  1. Plant parts (vegetative) of certain plants are used for the process of reproduction.
  2. It is natural process also can be practised artificially for agricultural purposes.
  3. Plants that have lost the ability to reproduce by seeds (sexual reproduction) can be reproduced by these methods.
  4. All plants are genetically similar to their parent and other plants produced by the same parent. Hence, they are clones. There is no variation in them/such plants. Therefore, the quality of the plant is maintained.

Question 5 : Why is DNA copying an essential part of the process of reproduction?

Answer : DNA copying is an essential part of the process of reproduction because it ensures the same blueprint of the body design is maintained.

Page 140

Question 1 : How is the process of pollination different from fertilisation?

Answer :

Pollination Fertilisation
1. It is the process of transfer of pollen grains from anthers of a flower to stigma of a flower. 1. It is the union of fusion of male and female gametes.
2. It is of two types:
i) Self-pollination
ii) Cross-polliination
2. It is of one type only.
3. It takes place by various pollinating agencies. 3. It takes place by natural/artificial means.
4. If successful then it results in fertilisation. 4. It results in seed and fruit formation.

Question 2 : What is the role of the seminal vesicles and the prostate gland?

Answer : Seminal vesicles : It produces a nutritive secretion needed for the sperms.

Prostate glands : It produces a fluid medium necessary for transport of the sperms.

Question 3 : What are the changes seen in girls and the time of puberty?

Answer : Following changes are seen in girls at the time of puberty:

i) Breast enlarge and skin around the nipple darkens.
ii) Mensuration starts with monthly vaginal bleeding.
iii) Hips how rounding or contours.

Question 4 : How does the embryo get nourishment inside the mother’s body.

Answer : Placenta supplies the nourishment to the embryo inside the mother’s body.

Question 5 : If a woman is using a copper-T, will it help her to keep away from sexually transmitted disease?

Answer : No, because sexually transmitted disease can be prevented only by using a covering called female condom/diaphragm.

Text Book Questions Solved.

Question 1 : Asexual reproduction takes place through budding in

a) Amoeba
b) Yeast
c) Plasmodium
d) Leishmania

Answer : (b) Yeast.

Question 2 : Which of the following is not a part of the female reproductive system in human beings?

a) Ovary
b) Uterus
c) Vas deferens
d) Fallopian tube

Answer : (c) Vas deferens

Question 3 : The anther contains

a) Sepals
b) Ovules
c) Carpel
d) Pollen grains.

Answer : d) Pollen grains.

Question 4 : What are the advantages of sexual reproduction over asexual reproduction?

Answer : Advantages of sexual reproduction:

  1. Sexual reproduction takes place in presence of male and female individuals/parent/gametes.
  2. The offspring produced are genetically variable. Such organisms are successful in environment. This promotes diversity and evolution. It plays important role in origin of new species.
  3. It provides chances of many variations.

Question 5 : What are the functions performed by the testis in human beings?

Answer : Functions of testis:

  1. To produce germs cells (sex cells/male gametes) – sperms.
  2. To produce testosterone (male sex hormone)

Question 6 : Why does menstruation occur?

Answer : Menstruation occurs to remove the dead egg/unfertilised egg, the thick and spongy lining formed on the uterine wall. It marks the end of the cycle and to restart the next phase of egg maturation and provide a second chance for fertilisation of egg.

Question 7 : Draw a labelled diagram of the longitudinal section of a flower.

Answer :

Question 8 : What are the different methods of contraception?

Answer : Different methods of contraception are:

a) Creating mechanical barriers in the body.
b) Changing hormonal balance in the body.
c) Implanting contraceptive devices in the body.
d) Removing or blocking the ducts of reproductive system.
e) Abstinence (Stopping from doing).

Question 9 : How are the modes for reproduction different in unicellular and multicellular organisms?

Answer :

Modes of reproduction in unicellular organisms Modes of reproduction in multicellular organisms
1. The mode of reproduction is simple and involves the division of the parent cell. 1. The mode of reproduction is complex and involves the production of specialised cells.
2. Simple modes of reproduction takes palce. 2. Complex mode of reproduction takes place.
3. No specialised system/ tissue/ cells are involved. No germ cells/ sex cells are formed. 2. Specialised system/tissue/cells are involved. Germ cells/sex cells are formed.
4. Fertilisation process is absent. 4. Fertilisation process is present.
5. No variation in the individuals take place. 5. Variation in the individuals produced take place.
6. Only one individual is involved. 6. Two individuals of opposite sex are involved.

Question 10 : How does reproduction help in providing stability to population of species?

Answer : Those individuals that reproduce by sexual mode they produce organisms/individuals  with new combinations of DNA.  These new combinations are the variants of the parental combination that have the ability to survive better in the changed environmental conditions. This provides the stability of the population of a species in a given time.

Question 11 : What could be the reasons for adopting contraceptive methods?

Answer : Reasons are:

i) To maintain personal – reproductive health.
ii) To avoid contact of sexually transmitted diseases (STD) such as AIDS.
iii) To avoid having children.
iv) To avoid unwanted pregnancies.