Human Reproduction — BIOLOGY STD 12 Science — Question

Give reasons : Innate immunity is also known as non-specific immunity.

Rearrange the following in increasing order of evolution: Gnetales, Ferns, Zosterophyllum, Ginkgo.

What do you understand by phenotype and genotype? Explain by giving an exmple.

Why do high altitude areas have brighter sunlight and lower temperatures as compared to the plains?

Who proposed the famous double stranded helical structure of DNA?

Explain the following in context of cancer:
Benign tumour.

A cross was carried out between two pea plants showing the contrasting traits of heightof the plant. The result of the cross showed 50% of parental characters.

1. Work out the cross with the help of a Punnett square.
2. Name the type of the cross carried out.

A list of three flowering plants is given below. Which ones out of them are:

1. Monoecious
2. Bearing pistillate flowers?

List: Date palm, Cucurbits and Pea.

Describe the process of parturition in humans.

Is it true that if the dissolved oxygen level drops to zero the water will become septic? Given example which could lower the dissolved oxygen content of an aquatic body.