Advertisements
Advertisements
प्रश्न
In humans, males are heterogametic and females are homogametic. Explain. Are there any examples where males are homogametic and females heterogametic?
Advertisements
उत्तर
The term homogametic and heterogametic refer to the organism depending upon whether all the gametes contain one type of sex chromosome (Homo = same) or two different types of sex chromosomes (Hetero = different) Humans show XX/XY type of sex determination i.e. Females contain 2 copies of X chromosome and males contain 1 X and 1 Y chromosome. Therefore, ova produced by females contain the same sex chromosome i.e. X. On the other hand, the sperms contain 2 different types of chromosomes i.e. 50% sperms have X and 50% have Y chromosome open from half the autosomes (Meiosis) Therefore, the sperms are different with respect to the composition of sex chromosome. In case of humans, females are considered to be homogametic while males are heterogametic. Yes, there are examples where males are homogametic and females are heterogametic. In some birds, the mode of sex determination is denoted by ZZ (males) and ZW (females).
APPEARS IN
संबंधित प्रश्न
Fill in the following blank with suitable word :
Genes always work in ................ .
Fill in the following blank with suitable word :
The...............chromosomes for a ............are XX whereas that for a ..............are XY.
If a normal human cell has 46 chromosomes, how many chromosomes will be there in a human (i) sperm cell, and (ii) zygote?
A normal cell of human body contains 23 pairs of chromosomes. The number of chromosomes in a sex cell (sperm or ovum) of a human being is most likely to be :
(a) 46
(b) 23
(c) 21
(d) 42
The two versions of a trait (character) which are brought in by the male and female gametes are situated on :
(a) copies of the same chromosome
(b) sex chromosomes
(c) two different chromosomes
(d) any chromosomes
In human males all the chromosomes are paired perfectly except one. This/these unpaired chromosomes is/are :
(i) large chromosome
(ii) small chromosome
(iii) Y chromosome
(iv) X chromosome
The person A has only B chromosomes in all its gametes. On the other hand, another person C has chromosome D in half of gametes and chromosome E in the other half of gametes. When chromosomes B and D combine during fertilisation, a female zygote results. On the other hand, combination of B and E chromosomes produces a male zygote.
(a) What are chromosomes (i) B (ii) D, and (iii) E?
(b) Out of B, D and E, which two chromosomes are of the same type?
(c) Which chromosome is smaller in size?
(d) What is the general name of chromosomes such as B and E?
(e) Out of the two persons A and C, which one is (i) male, and (ii) female?
Define the following:
Autosomes
Choose the correct answer:
Males have more chances of suffering from sex-linked disease because of ___________
Choose the correct answer:
A single recessive trait, able to express must be on _________
With the help of a chart, explain the method of sex determination in honeybees.
Give Technical Term:
The cell which determines the sex of a baby.
ZW-ZZ system of sex determination occurs in
Brief about female heterogamety.
There are five daughters and no son in a family. It is because
Which type of sex determination is observed in honey bee?
Diploid larvae which get royal jelly as food develops into ____________ and other develops into workers (sterile females).
Identify the organism in which ZZ-ZW type of sex determination is observed.
In XO type of sex determination ______.
A zygote which has an X-chromosome inherited from the father will develop into a ______.
Human offspring’s sex is determined ______
Which of the following statements is not true with respect to variation?
Select the statements that describe characteristics of genes
- genes are specific sequence of bases in a DNA molecule
- a gene does not code for proteins
- in individuals of a given species, a specific gene is located on a particular chromosome
- each chromosome has only one gene
Also describe as to, who determines the sex of an unborn child? Mention whether temperature has a role in sex determination.
Name the two types of gametes produced by men.
What is sex determination? Explain the mechanism of sex determination in the case of birds.
