Question

During human gestation, rudiments of all organs develop

(A) in the first trimester.

(B) in the second trimester.

(C) in the third trimester.

(D) during the blastocyst stage.

Short answer

1. The option “in the first trimester” is true.

2. The option “in the second trimester” isfalse.

3. The option “in the third trimester” is false.

4. The option “during the blastocyst stage” is false.

Step-by-step solution

Human gestation

The gestation period in humans lasts for about nine months. During this period, the fetus develops inside the mother’s womb until the organs are formed, and development is complete. The gestation period starts immediately after conception and ends after the child is born.

Explanation of option ‘(A)’

During the first trimester, that is, during the first three months of gestation, the fetus acquires nutrition from the placenta. The placenta is a cord-like connection that connects the fetus and the mother. During this phase, the rudimentary organs like the nervous system, heart, and face develop.

Thus, during the first trimester, rudimentary structures develop.

Therefore, the given option is true.

Explanation of option ‘(B)’

During the second trimester, the fetus begins to grow in size. The rudimentary organs that were formed in the first trimester develop completely. The fetus can hear sounds from the external environment during this stage of development.

Thus, during the second trimester, organs develop entirely.

Therefore, the given option is false.

Explanation of option ‘(C)’

During the third trimester, the body of the fetus continues to grow in size and also increases in weight. The immature lungs also start to mature, and the fetus turns its head towards the vagina.

Thus, during the third trimester, the fetus grows in size and weight.

Therefore, the given option is false.

Explanation of option ‘(D)’

The blastocyst stage starts after three days post-fertilization. The fertilized ovum divides rapidly to give rise to multiple cells that form the blastocyst. The inner cells of the blastocyst form the embryo, and the outer cells form an external covering for the developing embryo.

Thus, during the blastocyst stage, the fertilized ovum produces the embryo.

Therefore, the given option is false.