(i) Ramesh is right in this matter as early or child marriage can endanger the life of girl.
(ii) 18 years
(iii) The reproductive organs of girls below 18 years are not fully prepared for pregnancy. Also, early pregnancy may have serious harmful effects on the health of the young mother.

(a) A develops into the embryo.
B develops into the endosperm.
(b) 1. The endosperm development starts from the primary endosperm cell containing the primary endosperm nucleus.
2. In the most common type of endosperm development, the primary endosperm nucleus undergoes successive free nuclear divisions to give rise to a number of free nuclei; at this stage, it is called free nuclear endosperm.
3. Subsequently wall formation takes place from the periphery and proceeds towards the centre and the endosperm becomes cellular.
4. This type of endosperm development is seen in coconut; the water of the tender coconut represents the free nuclear endosperm with thousands of nuclei in it and the white kernel around it represents the cellular endosperm.
5. In albuminous seeds, some amount of endosperm persists in the mature seed, as the developing' embryo does not consume it fully, e.g. wheat/maize.
6. In exalbuminous seeds, the endosperm is completely consumed by the developing embryo before seed maturation, e.g. groundnut and pea.

An embryo sac is called monosporic because it develops from one of the four megaspores formed from the division of megaspore mother cell.

Since the testes are very sensitive to temperature, if they do not descend into the scrotum prior to adolescence, then they will stop producing sperms that will lead to infertility in males, a condition known as cryptorchidism.

A - FSH and oestrogen, B - LH and C - Progesterone

The papaya trees are all of the same species. Some trees bear bisexual flowers, both male and female parts are present. But the flowers of other trees are unisexual; they bear only either male or female part. So the trees that bear only male flowers cannot produce fruit.

In our society, Women are blamed for giving birth to daughters. This is wrong because sex of the baby is determined by the sperm that can have either X or Y-chromosomes.
Since Women have only one type of chromosome (X) in all the ova. 
If the sperm having X-chromosome fertilises the ovum (X), the resulting zygote (XX) will become a female. 
If the sperm having Y-chromosome fertilises the ovum (X), the resulting zygote (XY) will become a male.

(a) GIFT is an assisted reproduction which helps in the transfer of an ovum collected from a donor into the fallopian tube of another female who cannot produce ova but can provide suitable environment for fertilization and further development of embryo in the oviducts.
(b) CU-T and CU-7 are the intrauterine contraceptive devices used as means of birth control. When introduced into the female reproductive tract, the copper ions start releasing. These ions reduce sperm motility and their fertilizing capacity. The hormones released make the uterus unsuitable for implantation and the cervix hostile to the sperms.

(i) Rates of sexually transmitted diseases/infections have increased as people are getting less precautious. They are not using any kind of precautions like condoms in order to prevent spread of STDs.
(ii) Sexually transmitted diseases/infections are mainly caused by various bacteria, viruses and some yeasts.
(iii) Symptoms that one experiences to suspect sexually transmitted infection include
(a) Burning/itching in vaginal areas.
(b) Unusual discharge from the penis.
(c) Pain in pelvic/ abdominal region.
(OR)
(ii) STDs/STIs can be prevented by the following two ways
(a) Avoiding sex with unknown/multiple partners.
(b) Using condoms during intercourse.

(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
Explanation:
Family planning helps in maintaining reproductive health.

(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation:
Geitonogamy is a type of pollination in which pollen grains of one flower are transferred to the stigma of another flower belonging to either the same plant or genetically similar plant. It usually occurs in plants which show monoecious condition (unisexual male and female flowers borne on the same plant. Thus, geitonogamy is functionally cross pollination as it involves pollinating agent to carry out pollination, but genetically it is similar to autogamy (self-pollination) since the pollen grains come from the genetically same plant.