NCERT Class 10: Science-Intext Solutions
Chapter 08-How do Organism Reproduce?-Intext Solutions
NCERT Book Page Number-128
Q.1. What is the importance of DNA copying in reproduction?
Ans. DNA contains information for the inheritance of characteristics from parents to next generation. DNA present in nucleus of cells are the information source for making protein. If information is different, different type of protein will be made that will lead to altered body design.
Q.2. Why is variation beneficial to the species but not necessarily for the individual ?
Ans. Variations are useful for the survival of species in changed environmental situations. If a population of reproducing organism were suited to a particular niche and if the niche is drastically altered the population could be wiped out. However, some variations are present some species will survive. Thus, variation is useful to species but not the individual.
NCERT Book Page Number-133
Q.1. How does binary fission differ from multiple fission ?
Ans. Binary fission : In this splitting of unicellular organism occurs into two daughter cells. Example : Amoeba.
Multiple fission : In this splitting of unicellular organism occurs into many daughter cells. Example : Malarial parasite Plasmodium.
Q.2. How will an organism be benefitted if it reproduce through spores ?
Ans. The spores are covered by thick walls that protect them until they come in contact with suitable moist surface and begin to grow.
Q.3. Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration ?
Ans. The reason is that complex organisms are not further merely random collection of cells. Specialized cells are organised in them as tissues which are organised into organs. These organs have to be placed at definite positions in the body. So, regeneration is not possible in multicellular organisms.
Q.4. Why is vegetative propagation practised for growing some types of plants ?
Ans. (i) Plants raised by vegetative propagation can bear flower and fruits earlier than those pro¬duced from seeds.
(ii) Such methods also make possible the propagation of plants such as banana, orange, rose and jasmine that have lost the capacity to produce seeds.
(iii) All plants produced by this method are genetically similar enough to the parent plant to have its all characteristics.
Q.5. Why is DNA coping essential part of the process of reproduction?
Ans. DNA contains information for the inheritance of features from parents to next generation. DNA present in nucleus of cells are the information source for making protein. If information is different, different type of protein will be made that will lead to altered body design.
NCERT Book Page Number-140
Q.1. How is the process of pollination different from fertilisation?
Ans. Differences between pollination and fertilisation.
Pollination : Pollination refers to the process of transfer of pollen grains from anther to stigma of flower.
Fertilisation : Fertilisation refers to fusion of male and female gamete to form a zygote.
Q.2. What is the role of the seminal vesicles and the prostate gland ?
Ans. The secretions from seminal vesicles and the prostate gland lubricate the sperms and provide a fluid medium for easy transport of sperms. Their secretion also provides nutrients in the form of fructose, calcium, and some enzymes.
Q.3. What are the changes seen in girls at the time of puberty ?
Ans. During puberty
breast size begins to increase
girls begin to menstruate at around this time.
growth of pubic hair occurs.
the oil glands and sweat glands become more active in the skin and result in the appear¬ance of pimples.
Q.4. How does the embryo get nourisment inside the mother’s body ?
Ans. After fertilisation the lining of uterus thickens and is richly supplied with blood to nourish the growing embryo. The embryo gets nutrition from the mother’s blood with the help of a special tissue called placenta. It is embedded in the uterine wall. Placenta contains villi on the embryo’s side of the tissue and blood spaces on mother’s side surrounding the villi. This provides a large surface from mother to the embryo and waste products from embryo to mother.
Q.5. If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases ?
Ans. Copper-T cannot protect the woman from acquiring sexually transmitted disease. It will protect her from only unwanted pregnancy.