What do you understand by fertility and mortality? How are these influenced by biological and socio-ecological factors? (Answer in 250 words)

- What do you understand by fertility and mortality? How are these influenced by biological and socio-ecological factors? (Answer in 250 words)
Introduction
Fertility is realised reproductive performance, mortality the incidence of death in a population. Both are shaped by biological capacity and by the social and ecological conditions that decide how far capacity is used.
Body
1. The concepts and their measures: fertility is measured by the crude birth rate, age-specific fertility rates, total fertility rate and net reproduction rate, and is distinguished from fecundity, the biological capacity. Mortality is measured by the crude death rate, age-specific rates, infant and under-five mortality, maternal mortality ratio and life expectancy. India's total fertility rate is now around 2.0, below replacement, with infant mortality near 28 per thousand, both approximate.
2. Biological influences: age at menarche and menopause set the reproductive span; ovulatory function, nutritional status, lactational amenorrhoea lengthening birth intervals, fetal loss and subfecundity all limit realised fertility. On mortality, birth weight, genetic disorders such as sickle cell disease in central India, immune competence, sex differentials in survival and senescence operate directly.
3. Socio-ecological influences: age at marriage, universality of marriage, widow remarriage, contraceptive use, son preference and female education, the strongest single predictor, govern fertility. Mortality responds to nutrition, sanitation, disease ecology such as malaria in the forested tribal belt, altitude and hypoxia depressing birth weight, health service access and conflict. Kerala against Bihar is the standing Indian contrast.
4. How they interact: social factors work through biological channels, education delaying marriage and shortening exposure, breastfeeding norms extending birth intervals, and falling infant mortality reducing desired family size.
Conclusion
Biology sets the outer limits; social and ecological conditions decide where within those limits a population sits. The demographic transition is that second set of conditions changing.