Class 12th Biology 2018 Set1 Delhi Board Paper Solution
Question 15
Explain the mechanism of ‘sex determination’ in birds. How does it differ from that of human beings?
Answer
In birds, sex determination is of ZW-ZZ type.
In this type of homogametic and haven ZZ sex chromosomes and females are heterogametic with ZW pair of sex chromosomes.
Parents : Male X Female
ZZ ZW
Gametes : (Z) (Z) (Z) (W)
Tr : Female Male
Where as in humans,the chromosomal mechanism of sex determination is XX-XY type. The human male is heterogametic and have XY sex chromosome and human female is homogarnetie with XX sex chromosomes.
Popular Questions of Class 12th biology
- Q:- What is spermatogenesis? Briefly describe the process of spermatogenesis.
- Q:- Why is reproduction essential for organisms? Answer
- Q:- Write a short note on
(a) Adaptations of desert plants and animals
(b) Adaptations of plants to water scarcity
(c) Behavioural adaptations in animals
(d) Importance of light to plants
(e) Effect of temperature or water scarcity and the adaptations of animals. - Q:- With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte.
- Q:- What is DNA fingerprinting? Mention its application.
- Q:- What is oogenesis? Give a brief account of oogenesis.
- Q:- Describe the structure of a seminiferous tubule.
- Q:- What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion.
- Q:- With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.
- Q:- Explain the Law of Dominance using a monohybrid cross.
Recently Viewed Questions of Class 12th biology
- Q:- Name the primary and secondary lymphoid organs.
- Q:- Name the parts of an angiosperm flower in which development of male and female gametophyte take place.
- Q:- Differentiate between a zoospore and a zygote.
- Q:- Do you think that friends can influence one to take alcohol/drugs? If yes, how may one protect himself/herself from such an influence?
- Q:- Explain (in one or two lines) the function of the followings:
(a) Promoter
(b) tRNA
(c) Exons - Q:- Identify each part in a flowering plant and write whether it is haploid (n) or diploid (2n).
(a) Ovary _______________
(b) Anther _______________
(c) Egg _________________
(d) Pollen__________________
(e) Male gamete _______________
(f ) Zygote ___________________ - Q:- How does the transmission of each of the following diseases take place?
(a) Amoebiasis
(b) Malaria
(c) Ascariasis
(d) Pneumonia - Q:- Can we call human evolution as adaptive radiation?
- Q:- Differentiate the following and give examples of each:
(a) Innate and acquired immunity
(b) Active and passive immunity - Q:- Describe the structure of a seminiferous tubule.