Science (English Medium) Class 12 - CBSE Question Bank Solutions for Biology

Which of the following hormones is not secreted by human placenta?

Eye lens is formed from ______.

Which extra-embryonic membrane in humans prevents desiccation of the embryo inside the uterus?

The first movements of the foetus and appearance of hair on its head are usually observed during which month of pregnancy?

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

Urine test during pregnancy determines the presence of ______.

In the event of pregnancy, the corpus luteum persists under the influence of ______.

In the development of the human body, the ectoderm is responsible for the formation of ______.

The early stage human embryo distinctly possesses ______.

Relaxin is the hormone secreted by the placenta.

Mark the odd one.

Which of the following statements are correct with respect to hormones secreted by the placenta?

1. The placenta secretes relaxin during the later stage of pregnancy.
2. The placenta secretes a high amount of FSH during pregnancy.
3. The placenta secretes relaxin during the initial stage of pregnancy.
4. The placenta secretes hCG and hPL during pregnancy.

The concentration of which of the following substances will decrease in the maternal blood as it flows from embryo to placenta through the umbilical cord?

The human foetus within the uterus

1. Oxygen
2. Amino Acids
3. Carbon dioxide
4. Urea

To answer the question, study the graphs below for Subjects 1 and 2 showing different levels of certain hormones.

Subject 2 has a higher level of hormone B, which is ______

Which of the following is not a function of the placenta?

Read the following and answer from given below:

Cleavage is the series of rapid mitotic divisions in the zygote and forms blastula. The 2, 4, 8, 16 daughter cells are called blastomeres. An embryo with 64 blastomeres is known as a blastocyst and has a blastocoel cavity. Blastocyst gets implanted in the uterine wall and leads to preganancy.

The solid mass of cells with 16 blastomeres is called ______

Read the following and answer from given below:

Cleavage is the series of rapid mitotic divisions in the zygote and forms blastula. The 2, 4, 8, 16 daughter cells are called blastomeres. An embryo with 64 blastomeres is known as a blastocyst and has a blastocoel cavity. Blastocyst gets implanted in the uterine wall and leads to pregnancy.

At which stage of embryonic development does trophectoderm develop?

Read the following and answer from given below:

Cleavage is the series of rapid mitotic divisions in the zygote and forms blastula. The 2, 4, 8, 16 daughter cells are called blastomeres. An embryo with 64 blastomeres is known as a blastocyst and has a blastocoel cavity. Blastocyst gets implanted in the uterine wall and leads to pregnancy.

The correct sequence of various structures formed during embryonic development is ______

Except endocrine function, what are the other functions of placenta.

Water logging and soil salinity are some of the problems that have come in the wake of the Green Revolution. Discuss their causes and adverse effects to the environment.