Class 12 Biology

Few problems along with their solutions from this chapter are given follows:

Q. Increased IMR and decreased MMR in a population will

(a) cause rapid increase in growth rate

(b) result in decline in growth rate

(c) not cause significant change in growth rate

(d) result in an explosive population/exp

Ans. (c) not cause significant change in growth rate

IMR (Infant Mortality Rate) and MMR (Maternal Mortality Rate) both are responsible for affecting the growth rate inversely. It means decline in IMR as well as MMR will result in high population growth and vice-versa.

Here, if IMR is increased then it will result in decline in growth rate while decreased MMR will cause an increase in growth rate.

Therefore, in the above situation, both cases act oppositely due to which there will be no significant change in growth rate.

Q. The present population growth rate in India is alarming. Suggest ways to check it.

Ans. The alarming population growth rate in India might lead to an absolute scarcity of even the basic requirements, i.e., food, shelter and clothing, in spite of significant progress made in those areas.

Following are some important ways to check the population growth in India:

(i) By promoting use of birth control measures to motivate smaller families,

(ii) By providing incentives to couples with small families.

(iii) By educating people about consequences of uncontrolled population growth.

Q. Briefly explain IVF and ET, What are the conditions in which these methods are advised?

Ans. IVF stands for in-vitro fertilisation. In this technique, sperm from the male (or donor) and ovum from the female (or donor) are taken out. Ovum is then fertilized in the laboratory set up under simulated conditions.

ET refers to embryo transfer. It is the next procedure after IVF. The zygote formed is collected and introduced into the uterus of a host or surrogate mother at an appropriate time (secretory phase). Embryo up to 8 blastomeres stage is transferred in the fallopian tube whereas an embryo with more than 8 blastomeres is transferred to the uterus.

These methods are employed in a case where the medical treatment and psychotherapy may have failed in helping the couple in conception. These methods require very high degree of precision and can only be carried out by highly specialized doctors.

Class 12 Biology NCERT Exemplar Problems:

The NCERT Exemplar problems are considered to be the most applicative kind of problems which help to enhance a student’s critical thinking and problem solving ability. These problems are designed to increase the application skills of the students.

Students must solve all the NCERT Exemplar Problems to assess their understanding about the various concepts of the subject and analyse their strong and weak areas.

Main topics discussed in Class 12 Biology, Chapter 4- Reproductive Health, are:

• Reproductive health – problems and strategies
• Population explosion and birth control
• Medical termination of pregnancy
• Sexually transmitted diseases
• Infertility.