How do Organisms Reproduce? Science - How do Organisms Reproduce?

The normal body cell of an organism contains 28 pairs of chromosomes. The number of chromosomes present in its germ cell will be:

The offsprings formed by asexual reproduction method have greater similarity among themselves because :

1. Aexual reproduction involves only one parent.
2. Aexual reproduction involves two parents.
3. Aexual reproduction involves gametes.
4. Axual reproduction does not involve gametes.

The micro-organism which reproduces by multiple fission is the one which causes the disease known as:

In a flower, the parts that produce male and female gametes are respectively:

One of the following occurs in the reproductive system of flowering plants as well as that of humans. This is:

Fill in the following blanks with suitable words:
The menstrual cycle is controlled by _______.

Fill in the following blanks with suitable words:
The process of __________ ensures continuity of life on earth.

Fill in the following blanks with suitable words:
The name of the structure in the flower in which the male gamete is formed is ________.

Fill in the following blanks with suitable words:
Flowering plants reproduce by __________ method of reproduction.

Fill in the following blanks with suitable words:
The term used to refer to the transfer of pollen from the stamen of one flower to the carpel of another flower of the same species is _________.

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

Name the organs which produce ova (or egg cells) in human females.

What is the life support system of a fetus?

What are the reproductive organs in a flower?

Fertilisation in humans can occur only once in a month. Why?

What is made in:

1. Anther.
2. Ovary, of a flower?

How do the insects help in cross-pollination?

Describe the process of reproduction in Hydra with the help of labelled diagrams. What is the name of this process of reproduction?

What is meant by ‘unisexual flowers’ and ‘bisexual flowers’ ? Give two examples of each.

What is meant by contraception? What are the different methods of contraception?

State the advantages of sexual reproduction over asexual reproduction.

How can you grow money plant bv vegetative propagation?

Describe the grafting method for the artificial propagation of plants with the help of labelled diagrams.

Explain why, more complex multicellular organisms cannot give rise to new organisms through regeneration.

Explain how, new Bryophyllum plants can be produced from the leaves of the old plant ? Illustrate your answer with the help of a labelled diagram.

What is done in the contraception method known as:

1. Vasectomy.
2. Tubectomy?

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.

1. What is device X?
2. What are Y?
3. Name the device Z.
4. What is the general name of these methods of birth control (or preventing pregnancy)?
5. The use of which contraceptive device, X or Z, can protect the persons from sexually transmitted diseases?

When an insect sits on the flower of a plant then some particles A present in the top of little stalks in the flower attach to its body hair. When this insect now sits on the flower of another similar plant, then particles A attached to the hair of insect are put on the top of a flask-shaped organ at the centre of flower. The particle A grows a long tube b from the top of flask-shaped organ through which C moves down and reaches the bottom part of flask-shaped organ. Here C fuses with the nucleus of d contained in structure E. the fusion of C and D forms a new cell f which grows and develops into a seed of the plant.

1. What are particles A? What is the process of transferring A from one flower to another flower of similar plant by the insect known as?
2. What is the name of tube B?
3. What is C which moves down through the tube B?
4. Name D and E.
5. What is F?

In the surgical method of birth control available for males, the structures A in the reproductive system are cut and ligated (tied up) at both ends. This prevents the reproductive cells B from coming out from the organs C where they are made in the male body. Since B cannot come out from the male body, they cannot fuse with cell D in the body of a female and hence pregnancy is prevented.

1. What are structures A?
2. What are cells B?
3. Name the organs C.
4. What is cell D?
5. What is the name of this surgical procedure for birth control available to males?

A worm X found in freshwater and slow-moving streams has been accidently cut into three pieces. It was observed that in due course of time, each cut piece of the worm develops to become a complete worm by growing all the missing parts.

1. Name the worm X which can exhibit this phenomenon of making complete worm from its cut body parts.
2. Name another organism Y which possesses the same characteristic of growing fully from its cut body parts.
3. What is the name of this process in which a complete organism is formed from its cut body part.
4. State whether X and Y are unicellular and/or multicellular organisms.
5. Can a dog be produced completely form its cut body part (say, a cut tail) just like organisms X and Y? Why?