Human Reproduction — BIOLOGY STD 12 Science — Question

Explain the following terms with examples: Incomplete dominance.

Transplantation to save certain patients often fails due to rejection by the patient. What is transplantation? Which type of immune response is responsible for such rejections?

1. Identify the polarity from a to a', in the above diagram and mention how many more amino acids are expected to be added to this polypeptide chain.
2. Mention the DNA sequence coding for serine and the anticodon of tRNA for the same amino acid.
3. Why are some untranslated sequence of bases seen in mRNA coding for a polypeptide? Where exactly are they present on mRNA?

1. Differentiate between analogous and homologous structures.
2. Select and write analogous structures from the list given below:

1. Wings of butterfly and birds.
2. Vertebrate hearts.
3. Tendrils of bougainvillea and cucurbita.
4. Tubers of sweet potato and potato.

Explain why Bt cotton flowers undergo pollination by butterflies and bees inspite of being insect pest resistant?

Make a list of three household products along with the names of the microorganisms producing them.

What are biogeochemical cycles? Mention their two kinds, giving instances of each.

Can we call human evolution as adaptive radiation?

How has RNAi technique helped to prevent the infestation of roots in tobacco plants by a nematode Meloidegyne incognitia?

Give reason:

1. Population of different species are not capable of breeding with each other.
2. Intraspecific competition is more intense than interspecific competition.
3. Parasites tend to loose certain organs.