Class 12 Biology - Chapter Principles of Inheritance and Variation NCERT Solutions | How is sex determined in human beings?
How is sex determined in human beings?
Human beings exhibit male heterogamy. In humans, males (XY) produce two different types of gametes, X and Y. The human female (XX) produces only one type of gametes containing X chromosomes. The sex of the baby is determined by the type of male gamete that fuses with the female gamete. If the fertilizing sperm contains X chromosome, then the baby produced will be a girl and if the fertilizing sperm contains Y chromosome, then the baby produced will be a boy. Hence, it is a matter of chance that determines the sex of a baby. There is an equal probability of the fertilizing sperm haveup an X or Y chromosome. Thus, it is the genetic make up of the sperm that determines the sex of the baby.
More Questions From Class 12 Biology - Chapter Principles of Inheritance and Variation
- Q:- Explain the Law of Dominance using a monohybrid cross.
- Q:- A child has blood group O. If the father has blood group A and mother blood group B, work out the genotypes of the parents and the possible genotypes of the other offsprings.
- Q:- A diploid organism is heterozygous for 4 loci, how many types of gametes can be produced?
- Q:-
Explain the following terms with example
(a) Co-dominance
(b) Incomplete dominance - Q:- Define and design a test − cross?
- Q:- When a cross in made between tall plants with yellow seeds (Ttyy) and tall plant with green seed (Ttyy), what proportions of phenotype in the offspring could be expected to be (a) Tall and green. (b) Dwarf and green.
- Q:- Briefly mention the contribution of T.H. Morgan in genetics.
- Q:- Mention any two autosomal genetic disorders with their symptoms.
- Q:- What is point mutation? Give one example.
- Q:- Differentiate between the following −
(a) Dominance and Recessive
(b) Homozygous and Heterozygous
(c) Monohybrid and Dihybrid.
Popular Questions of Class 12 Biology
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- Q:-
Fill in the blanks:
(a) Humans reproduce __________. (asexually/sexually)
(b) Humans are__________. (oviparous/viviparous/ovoviviparous)
(c) Fertilization is __________ in humans. (external/internal)
(d) Male and female gametes are __________. (diploid/haploid)
(e) Zygote is __________. (diploid/haploid)
(f) The process of release of the ovum from a mature follicle is called__________.
(g) Ovulation is induced by a hormone called the __________.
(h) The fusion of male and female gametes is called _____________.
(i) Fertilisation takes place in _____________.
(j) Zygote divides to form _____________which is implanted in uterus.
(k) The structure which provides vascular connection between fetus and uterus is called ____________. - Q:- What do you think is the significance of reproductive health in a society?
- Q:- Group the following as nitrogenous bases and nucleosides:
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- Q:- Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics (use the internet).
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