Biodiversity and Conservation — BIOLOGY STD 12 Science — Question

Write the symptoms of haemophilia and sickle–cell anaemia in humans. Explain how the inheritance pattern of the two diseases differs from each other.

Differentiate between perisperm and endosperm by giving one example of each.

During an excavation assignment, scientists collected pollen grains of a plant preserved in deeper layers of soil. Analyse the properties of pollen grains which help in the fossilization.

If the meiocyte of a maize plant contains 20 chromosomes, write the number of chromosomes in the endosperm and embryo of the maize grain and give reasons in support of your answer.

In cattle, hornless (H) is dominant over horned (h) and black (B) is dominant over red (b). Consider that these two pairs of genes assort independently.

1. What proportion of the offspring from the cross, BbHh x bbhh, would be black and hornless?
2. From the cross Bbhh x Bbhh, how many will be:

1. Black and horned.
2. Red and horned.

Give the scientific name of the parasite that causes malignant malaria in humans. At what stage does this parasite enter the human body? Trace its life cycle in human body.

Define and design a test-cross###Explain the test cross by example.

Why is the length of a food chain in an ecosystem generally limited to 3-4 trophic levels? Explain with an example.

Write any five common antibiotics with their sources.