Tag: reproduction in humans

Questions Related to reproduction in humans

Fraternal twins in humans are produced when

biology reproduction in humans twins reproduction and modern technology post fertilization events

  1. Two sperms fertilize an ovum and the first two blastomeres separate from each other

  2. One sperm fertilizes an ovum and the first two blastomeres separate from each other

  3. Egg develop parthenogenetically and first two blastomeres separate from each other

  4. Two ova are fertilized simultaneously

Show answer
Correct Option: D
Explanation:

Fraternal twins are also called as 'dizygotic'. This means there is fertilization of two seperate eggs(ova) by two individual sperms simultaneously. They are implanted in the uterine wall at the same time. They usually develop in two separate amniotic sacs. They are also called as 'biovular' since two eggs form two zygotes.
So, the correct is answer is 'Two ova are fertilized simultaneously'.

What are identical twins?

biology reproduction in humans twins reproduction and modern technology post fertilization events

  1. Heterozygous

  2. Homozygous

  3. Monozygotic

  4. Dizygotic

Show answer
Correct Option: C
Explanation:

Image result for monozygotic identical twin
Twins are two offsprings produced by the same pregnancy. Twins can either be monozygotic (identical twin), meaning that they develop from one zygote that splits and forms two embryos, or dizygotic (fraternal twin), which are produced from two eggs. Thus, the correct answer is option C.

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

biology reproduction in humans twins reproduction and modern technology post fertilization events

  1. Dizygotic twins

  2. Monozygotic twin

  3. Fraternal twins

  4. Both A and C

Show answer
Correct Option: D
Explanation:

Dizygotic twins may occur if two or more oocytes are released in one cycle. If each is fertilized, dizygotic twins may result. Fertility drugs are a common cause for dizygotic twins, but other factors, like family history, maternal age or weight, can also lead to dizygotic twinning. Thus, the correct answer is option D.

Monozygotic twins develops from

biology reproduction in humans twins reproduction and modern technology post fertilization events

  1. Different zygotes

  2. Different ova

  3. Different sperms

  4. Same zygote

Show answer
Correct Option: D
Explanation:

  • There are two types of twins, Fraternal or dizygotic twins, and monozygotic twins.
  • When the zygote, during the cleavage, separates and forms two different cells and both of them grow individually as embryos, they form the monozygotic twins.
  • Monozygotic twins are of the same sex.
  • When 2 zygotes are fertilized by two different sperms they form the dizygotic twins.
  • They can be of different sex.

So, the correct option should be 'Same Zygote'.

Concordant type of twins are

biology reproduction in humans twins reproduction and modern technology post fertilization events

  1. Free martins

  2. Dizygotic twins

  3. Monozygotic twins

  4. Both B and C

Show answer
Correct Option: C
Explanation:
Monozygotic or identical twins are those twins which are formed by the splitting of one zygote into two embryos. They have almost the same characteristics both phenotypically and genotypically. Dizygotic or fraternal twins are formed when two different eggs are fertilized by two different sperms.
so, the correct option is ' Monozygotic twins'.

Structure connecting the fetus to placenta is ________________.

zoology reproduction in humans placenta pregnancy and birth fertilization and post fertilization in humans

  1. Umbilical cord

  2. Amnion

  3. Yolk sac

  4. Chorion

Show answer
Correct Option: A
Explanation:

Umbilical cord is a narrow, tube-like structure that connects the fetus to the placenta.Through this tube, nutrients and oxygen are supplied from the mother to the baby and waste products are removed from the baby.

Which of the following hormones is not a secretory product of human placenta?

zoology reproduction in humans placenta pregnancy and birth fertilization and post fertilization in humans

  1. Human Chorionic Gonadotropin

  2. Prolactin

  3. Estrogen

  4. Progesterone

Show answer
Correct Option: B
Explanation:

Prolactin is secreted by the anterior lobe of pituitary gland. After parturition, secretion and storage of milk in mammary glands is under the influence of this hormone.

Fetus gets nourishment and oxygen through _______________.

zoology reproduction in humans placenta pregnancy and birth fertilization and post fertilization in humans

  1. Allantois

  2. Placenta

  3. Yolk sac

  4. Chorion

Show answer
Correct Option: B
Explanation:

Placenta is an intimate connection between the fetus and uterine wall of the mother to exchange the materials. Food materials and oxygen pass from the mother's blood into the fetal blood and fetal excretory products diffuse into maternal blood through placenta.

In humans the shape of fully formed placenta is

zoology reproduction in humans placenta pregnancy and birth fertilization and post fertilization in humans

  1. Cuboidal

  2. Columnar

  3. Pyramidal

  4. Discoidal

Show answer
Correct Option: D
Explanation:

The human placenta is both metadiscoidal and monodiscoidal. Discoidal refers to the structure of the placenta and mono meaning there is only one disc. Metadiscoidal refers to the way the developing placenta becomes discoidal- the villi are scattered at first and then restricted to one disc, that means the placenta becomes mono-discoidal.

So, the correct answer is 'Discoidal'.

Mother's blood flows into the foetus through placenta

zoology reproduction in humans placenta pregnancy and birth fertilization and post fertilization in humans

  1. True

  2. False

Show answer
Correct Option: A
Explanation:
The placenta is a temporary association between the foetal and maternal tissues. It acts as a barrier between the foetus and mother and is contributed by both foetal and maternal tissue. Exchange of gases takes place through the placenta. The foetus obtains nutrients and oxygen from the mother's blood as the mother's blood can flow into the foetus through the placenta.
Hence, the statement given in the question is correct.
So, the correct answer is 'True'.