Which type of animals were the Dinosaurs having feathers?

$A$ very small population of a species faces a greater threat of extinction than a larger population. Provide a suitable genetic explanation.

$A$ child who inherits an $Y$-chromosome from her father will be a girl.

What is the probability percentage of a zygote developing into a male or female offspring in humans?

$(a)$ "Recent fossils are found closer to the earth's surface." Comment on the statement stating reason.
$(b)$ List two factors which could lead to the rise of new species.

An angiosperm plant having red coloured flowers when crossed with another having the same colour produced $40$ progenies,out of which $30$ plants were with red coloured flowers and $10$ plants were with white coloured flowers. Find out:
$(a)$ What is the possible genotype of parent plants?
$(b)$ Which trait is dominant and which is recessive?
$(c)$ What is this cross called and what is its phenotypic ratio?