Twins

Q.

How many eggs are released by a human ovary in a month? How many eggs do you think would have been released if the mother gave birth to identical twins? Would your answer change if the twins born were fraternal?

Q. How are twins formed?

Q. Assertion: In apomixis, plants of new genetic variation are produced.
Reason: In apomixis, reductional division takes place.

1. Both assertion and reason are true and reason is the correct explanation of assertion
2. Both assertion and reason are true but reason is not the correct explanation of assertion
3. Assertion is true but the reason is false
4. Both assertion and reason are false

Q.

How many eggs are released by a human ovary in a month? How many

eggs do you think would have been released if the mother gave birth to

identical twins? Would your answer change if the twins born were fraternal?

Q. Assertion: Twins may arise from a single egg or from two eggs.
Reason: One egg gives rise to identical twins by separation of blastomeres and two eggs produce non-identical twins

1. Both assertion and reason are true and the reason is the correct explanation of assertion.
   
2. Both assertion and reason are true but the reason is not the correct explanation of assertion.
3. Assertion is true but the reason is false.
   
4. Both assertion and reason are false.
   

Q.

Which of the following figures is associated with formation of fraternal twins?

1. ii and iii

2. ii and iv

3. i and iii

4. I and iv

Q. Which of the following prevents more than one sperm from penetrating a human oocyte?

1. Layer of cumulus oophorus
2. Development of fertilisation cone
3. Condensation of yolk of egg
4. Interaction of cortical chemicals with zona pellucida

Q.

what is the genetic nature of apomictics embryos

Q.

How many eggs are released by a human ovary in a month? How many

eggs do you think would have been released if the mother gave birth to

identical twins? Would your answer change if the twins born were fraternal?

Q. Identify the statements as true/false.
(xii) Fraternal twins are produced from two eggs.

Q. Given are diagrams showing the different stages in the process of fertilisation of an egg in human female reproductive tract.
Study the diagrams and answer the question.
Mention the chromosome number of the egg and zygote in humans.

Q.

give reason :dna fingerprinting cannot be used for distiguishing identical twins

Q. Identical twins are born when

1. One ovum crosses with one sperm
2. Two sperms crosses with one ovum
3. Two ova crosses with two sperms
4. None of the above

Q. If one of the two mono zygotic twin sibling had colour blindness what are the chance of other sibling being colour blind?

1. 25%
2. 50%
3. 100%
4. 75%

Q. Which of the following figures represent maternal twins?

1. 
2. 
3. 
4. 

Q.

Name a disorder inherited through $Y-$chromosomes.

Q. Foetus developing in the genital track without getting nourishment from the mother is a case of

1. Vivipary
2. Ovipary
3. Ovo-vivipary
4. None of the above

Q. Fraternal twins produced when

1. An egg is fertilized by two sperms
2. A divided egg has two set of chromosomes
3. Two eggs are fertilized simultaneously
4. A fertilized egg divided into two

Q. Give appropriate biological/technical terms for the following

The kind of twins formed from two fertilised eggs.

Q. Identify the statements as true/false.
(xi) Twins are the offsprings produced by the alternate pregnancies.

Q. Which are the two offspring developed in the same uterus but from fertilization of two different ova?

1. Dizygotic twins
2. Fraternal twins
3. Monozygotic twin
4. Both A and C

Q. Which of the following figures represent maternal twins?

1. 
2. 
3. 
4. 

Q. How dizygotic twins are formed?

Q. How many eggs and sperm are required to create identical twins in humans

Q.

Siblings share ____$\%$ of their genes while fraternal twins share ____$\%$ and identical twins share ____$\%$ of their genes (on average).

1. 50, 50, 50

2. 50, 50, 100

3. 100, 100, 100

4. 50, 50, 100