Exercises of how organises reproduce of 0 notes
Answers
Q1. What is the importance of DNA copying in reproduction?Ans. DNA copying is an important phenomenon of reproduction through which the organisms pass on their characteristics to their offspring. It maintains the characteristics in different generations of the species. It also produces variations which are useful for the survival of species for long time.
Q2. Why is variation beneficial to the species but not necessary for the individual?Ans. Accumulation of variations after several generations results in new set of traits required for survival. As they show results after many generations so they are not important for individual.
Q3. How does binary fission differ from multiple fission?Ans. Binauy Fission: An organism is divided into two individuals. Mitotic division takes place resulting in two identical individuals or daughter cells. e.g., Amoeba. Multiple Fission: Mitotic division takes place. The nucleus a ii diumrepeatedly to form a number of equal sized and similar individuals, e.g.,
Q4. How will an organism be benefited if it reproduces through spores?Ans. During adverse circumstances spore remain coated are means po tideve over layer. This helps an organism survive adverse conditions. Spores are means to tide over bad phases.
Q7. Why is DNA copying an essential part of the process of reproduction?Ans. DNA copying is needed because information stored in DNA is used to e make protein. Synthesis of different proteins will lead to altered body design. Thus, reproduction at its most basic level involves making copies of the blueprints of body design.
Q8. How is the process of pollination different from fertilization?Ans. Pollination is the transfer of pollen grains from the anther of a stamen to the stigma of a carpel. These are transferred by agents such as insects, birds, wind or water. Fertilization is defined as the fusion of a mele gamete (sperm) with a female gamete (ovary) to form a zygote by sexual reproduction.
Q9. What is the role of seminal vesicles and prostate gland?Ans. Seminal vesicles are a pair of thin-walled muscular and elongated sacs which secrete a fluid for nourishment of sperms. Prostate glands also produce a fluid which is released in the urethra along with secretion of seminal vesicle. It affects the vaginal pH so that sperms move smoothly inside the vagina.
Q10. What are the changes seen in girls at the time of puberty?Ans. At the time of puberty, breast size begins to increase, with darkening of the skin of the nipples. Also, girls begin to menstruate at around this time.
QUESTIONS FROM NCERT TEXTBOOK
Q1. Asexilal reprodnction takes place through budding in (a) amoeba (b) yeast. (c) plasnrodium. (d) leishrnaniia.Ans. (b) yeast
Q2. Which of the following is not a part of the temule reproductive system in human begins? (a) Ovary (b) Uterus (c) Vas deferens (d) Fallopian tubeAns. (c) Vas deferens
Q3. The anther cantains (a) sepals (b) ovules (c) carpel (d) pollen grainsAns. (d) pollen grains
Q4. What are the advantage of sexual reproduction acre asexual reproduction?Ans. In asexual reproduction, the offspring is almost identical to the parent because they have the same gene as their parent. Thus, variation is not present. Sexual reproduction involves fusion of male and female gametes. The offspring exhibits diversity of characters because they receive some genes from the mother and some from the father. The mixing of genes in different combinations, results in genetic variations. This variation leads to the continuous evolution of various species to produce various organisms.
Q5. What are the functions performed by testis in human beings?Ans. The function of testis is to produce sperms and male sex hormone called testosterone.
Q6. Why data menstruation occur?Ans. Menstruation occurs in females when the egg produced inside the cervix is not fertilized. Since the egg does not fuse with the male gamete, so the thick and soft lining of uterus having a lot of blood capillaries in it are not required. This unfertilized egg dies within a day and the lining breaks down shedding blood along with other tissues. This comes out of the vagina in the form of bleeding.
Q8. What are the different methods of contraception?Ans. Contraception is the method to avoid pregnancy. Various methods of contraception are as follows: Physical Barrier Methods: Use of condoms, diaphragms, cervical caps can be used. These prevent the entry of sperms into the female genital tract by acting as a barrier between them. Chemical Methods: Oral pills can be used which change the hormonal balance and stop release of egg. Vaginal pills kill the sperms. Surgical Methods: This includes vasectomy (sperm duct is removed) in males and tubectomy (removal of small portion of fallopian tube) in females.
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