English Medium कक्षा १० - CBSE Question Bank Solutions for Science

In the surgical method of birth control available for human females, the structures P in the reproductive system are cut and ligated (tied up) properly at both ends. This prevents the reproductive cell Q released by an organ R from entering the structures P so that Q is not available to fuse with another reproductive cell S coming from the male reproductive system. In this way, pregnancy is prevented.
(a) What are structures P?
(b) What is cell Q?
(c) Name the organ R.
(d) What is the reproductive cell S?
(e) What is the name of this surgical method of birth control available to females?

The human males use a device X made of a very thin rubber sheet as a covering on the male organ to prevent pregnancy. This device traps the gametes Y in it. In order to prevent pregnancy, the human females use a device Z which is a circle of rubber with a metal spring around it. The device Z is put inside the vagina to cover the cervix. It stops Y from going into the uterus.
(a) What is device X?
(b) What are Y?
(c) Name the device Z.
(d) What is the general name of these methods of birth control (or preventing pregnancy)?
(e) The use of which contraceptive device, X or Z, can protect the persons from sexually transmitted diseases?

A woman uses pills A as a method of birth control (or preventing pregnancy). The pills A stop the ovaries from releasing ovum into oviducts. Another woman uses pills B as a method of birth control. The pills B kill the sperms and prevent pregnancy.
(a) What do the pills A contain?
(b) What is the common name of pills A?
(c) What do the pills B contain?
(d) What is the common name of pills B?
(e) What is the general name of these methods of birth control?

A woman uses a device X made of a common metal for preventing pregnancy. This device works by preventing the implantation of fertilised egg cell (or embryo) in the female organ Y.
(a) What are the two names of device X?
(b) Name the organ Y.
(c) Can this method of contraception protect a woman from acquiring a STD?

A, B and C are three common STDs. A and C are caused by bacteria whereas B is caused by a virus D. The virus D reduces the immunity of the infected person to such a low level that the person can die of even very mild diseases.
(a) What could A and C be?
(b) What is B?
(c) Name the virus D?
(d) How can A, B and C be caused?
(e) Out of A, B and C, which one does not have a definite cure as yet?

 List four ways of preventing pregnancy. State two advantages of using such preventive methods.

What are Sexually Transitted Diseases (STD)? List two viral and two bacterial STDs. 

What is contraception ? List three reasons for adopting contraceptive methods. 

What is contraception? List four different methods. State four reasons for adopting contraceptive methods.

The period of pregnancy is called ______ 

Which of the following method of contraception protects from acquiring sexually transmitted diseases?

There is a greater possibility for the evolution of a new species in organisms which reproduce by ______

Would a Planaria cut vertically into two halves regenerate into two individuals? Complete Figure D and E by indicating the regenerated regions. 

A	B	C	D	E

From the internet, gather information about the chromosome numbers of five animals and five plants. Correlate the number with the size of organism and answer the following questions.

1. Do larger organisms have more number of chromosomes/cells?
2. Can organism with fewer chromosomes reproduce more easily than organisms with more number of chromosomes?
3. More the number of chromosomes/cells greater is the DNA content. Justify.

In tobacco plant, the male gametes have twenty four chromosomes.

What is the number of chromosomes in the female gamete?

What is the number of chromosomes in the zygote?