Class 12th Biology 2015 Set2 Delhi Board Paper Solution
Name the stage of human embryo at which it gets implanted. Explain the process of implantation.
The stage of the human embryo in which it gets implanted in the uterus is blastocyst.
The process of implantation can be explained as follows:
1. Fertilisation results in the formation of a diploid zygote.
2. As zygote moves through the uterus, mitotic divisions occur in the zygote that form 2, 4, 8, 16 daughter cells called blastomeres.
3. Embryo with 8 to 16 blastomeres is known as morula.
4. Morula undergoes further cleavage and develops into blastocyst; blastomeres of blastocyst get arranged into an outer layer called trophoblast and inner cells called inner cell mass.
5. Trophoblast layer of blastocyst gets attached to the endometrium while inner cell mass differentiate to form embryo.
6. After attachment, the uterine cells divide rapidly and causes the blastocyst to become embedded in the endometrium of the uterus. This leads to pregnancy.
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:- Describe the structure of a seminiferous tubule.
- Q:- What is oogenesis? Give a brief account of oogenesis.
- 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:- List the attributes that populations but not individuals possess.
- Q:- What is a bisexual flower? Collect five bisexual flowers from your neighborhood and with the help of your teacher find out their common and scientific names.
- Q:- In our society the women are often blamed for giving birth to daughters.
Can you explain why this is not correct? - Q:- Can you think and answer how a reporter enzyme can be used to monitor transformation of host cells by foreign DNA in addition to a selectable marker?
- 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:- Which is a better mode of reproduction sexual or asexual? Why?
- 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:- Is sex education necessary in schools? Why?
- Q:- What is pedigree analysis? Suggest how such an analysis, can be useful.
- Q:- Two heterozygous parents are crossed. If the two loci are linked what would be the distribution of phenotypic features in F1 generation for a dihybrid cross?