Question

30.
31.
What is placenta? Give the significance of pincenta.
How is the equal genetic contributation of ouale and female parents ensured in the progeny"
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Answer 1

Explanation:

2)Equal genetic contribution of male and female parents in the progeny is ensured by the equal inheritance of chromosome from each parent. Human possesses 23 pairs of chromosomes, of which 22 pairs are autosomes and 1 pair is the sex chromosomes. The two sex chromosomes in human are X and Y. Females have 2 X chromosomes and males have a X and Y chromosome. During the process of fertilization, a haploid sperm fuses with a haploid ovum to produce a diploid zygote. Zygote receives equal amount of genetic material from each parent and thus, retains the diploid nature on fertilization.

Answer 2

Answer:

The placenta is a temporary organ that connects the developing fetus via the umbilical cord to the uterine wall to allow nutrient uptake, thermo-regulation, waste elimination, and gas exchange via the mother's blood supply; to fight against internal infection; and to produce hormones which support pregnancy. Placentas are a defining characteristic of placental mammals, but are also found in marsupials and some non-mammals with varying levels of development.

Explanation:

Equal genetic contribution of male and female parents in the progeny is ensured by the equal inheritance of chromosome from each parent. ... Females have 2 X chromosomes and males have a X and Y chromosome. During the process of fertilization, a haploid sperm fuses with a haploid ovum to produce a diploid zygote.