No Two Individuals Are Absolutely Alike in a Population. Why? - Science


No two individuals are absolutely alike in a population. Why?



No two individuals are absolutely alike in a population due to variations taking place during the process of DNA copying.

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2013-2014 (March) All India Set 3

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Which mode of reproduction gives rise to variation?

Give the importance of variation in survival of species.

Complete the following table to get the differences between asexual and sexual reproduction:

Characteristics Asexual Reproduction Sexual Reproduction
Number of parents involved ........................... ..............................
Type of cells involved Somatic cells Germ cells
Type of cell division ............................ Meiosis and mitosis

What is meant by sexual reproduction?

Name two main processes of sexual reproduction

Describe the process of fertilization in human beings.

Choose the most appropriate answer.

Internal fertilization occurs

Choose the most appropriate answer.

The number of nuclei present in a zygote is

Indicate whether the following statements are True (T) or False (F).

Oviparous animals give birth to young ones. ( )

Indicate whether the following statement is True (T) or False (F).

Each sperm is a single cell. ( )

Indicate whether the following statement is True (T) or False (F).
A new human individual develops from a cell called gamete. ( )

Indicate whether the following statement is True (T) or False (F).

A zygote is formed as a result of fertilization. ( )

Indicate whether the following statement is True (T) or False (F).
An embryo is made up of a single cell. ( )

Give two differences between a zygote and a foetus.

In which female reproductive organ does the embryo get embedded?

Advantages of  sexual reproduction.

What is the name of sex cells (other than gametes)?

Name the organ which produces female sex cells.

Fill in the following blank with suitable word :

The cells involved in sexual reproduction are called .............

In which sort of reproduction are gametes involved?

What is formed when two gametes fuse?

State the advantages of sexual reproduction over asexual reproduction.

Distinguish between a gamete and a zygote.

The figure given alongside shows the human male reproductive organs. Which structures make sperms and seminal fluid?
(a) V makes sperms and X makes seminal fluid
(b) W makes sperms and Y makes seminal fluid
(c) X makes sperms and W makes seminal fluid
(d) Y makes sperms and V makes seminal fluid

One of the following process does not lead to the formation of clones. This is :
(a) fission
(b) fertilisation
(c) fragmentation
(d) tissue culture

Put a tick mark (✓) against the correct alternative in the following statement:

Amoeba is most commonly reproduced by:

Distinguish between the following pair of terms:

Budding and Regeneration.

Define the term Fetilization.

Define the term Puberty.

What is the function of uterus?

Multiple choice question. Tick (✓) the correct choice:

Which of the following glands is responsible for bringing about changes during adolescence in boys and girls?

  1. pituitary
  2. adrenal
  3. thyroid
  4. testis

Differentiate between the following:

Sperm and Ovum

Define the term Puberty.

Define the term Metamorphosis.

Mention the common method of reproduction in Amoeba.

Describe the various stages in the life cycle of a butterfly.

Sketch and label the diagram showing self- and cross-pollination.

In the sexual mode of reproduction, greater diversities are generated.

Answer in one sentence.

Enlist the external genital organs in the female.

Explain the histological structure of testis.

Answer the following question.

Explain the histological structure of ovary in human.

Answer the following question.

Which is the function of male accessory glands?

Answer the following question.

Explain the following parts of male reproductive system along with labelled diagram showing these parts- Testis, vasa deferentia, epididymis, seminal vesicle, prostate gland and penis.

What is atresia with respect to ovary in human females?

Give an account of external genitalia in human females.

Describe the histology of testis with help of labelled diagram.

Identify the labels from the given diagram.

Write an account of the seminal vesicle and bulbourethral gland in the male reproductive system.

Which are the components of pollination?

Animals which give birth to young ones directly are named as ______.

What are the different stages of sexual reproduction?

Which organs/glands produce eggs and sperms?

In an ovule, meiosis occurs in ______

Due to presence of which of the following chemical component, pollen grains can remain well preserved in fossil?

Testosterone is produced by ____________.

Which of the following is the male accessory gland?

Identify the INCORRECT statement.

Match column -1 with column - II and select the correct option.

  Column - I   Column - II
1. Seminal vesicles a. Membranous urethra
2. Scrotum b. Thermoregulatory
3. Tunica vaginalis c. Fibro muscular pouches
4. Cowper's gland d. Peritoneal covering

______ is the first stage of sexual reproduction.

The zygote divides repeatedly into a group of cells, which develops into different tissues and organs constituting a full body. This structure is known as ______.

Animals in which an embryo develops outside the body are called ______ animals.

______ lay thousands and sometimes millions of small, soft eggs in water.

The eggshell protects the ______ from the outer environment.

Name the two ways by which fertilisation in animals takes place.

What is external fertilisation?

Explain the two types of fertilization.

Explain the formation of the embryo.

Which is a better mode of reproduction, sexual or asexual? Why?


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