Human Reproduction — BIOLOGY STD 12 Science — Question

Write notes on ex-situ conservation of biodiversity

Explain the various types of interactions between species.

Answer the following questions:
Endosperm development precedes embryo development. Why?

A woman with blood group “A” marries a man with blood group “O”. Discuss the possibilities of the inheritance of the blood groups in the following starting with “yes” or “no” for each:

1. They produce children with blood group “A” only.
2. They produce children some with “O” blood group and some with “A” blood group.

Thalassemia and haemophilia are both Mendelian disorders related to blood. Write the symptoms of the diseases. Explain with the help of crosses the difference in the inheritance pattern of the two diseases.
OR
Why are thalassemia and hemophilia categorised as Mendelian disorders? Write the symptoms of these diseases. Explain their pattern of inheritance in humans. Write the genotypes of the normal parents producing a haemophilic son.

1. List the three different allelic forms of gene ‘I’ in humans. Explain the different phenotypic expressions, controlled by these three forms.
2. A woman with blood group'A'marries a man with blood group 'O'. Discuss the possibilities of the inheritance of the blood groups in the following, starting with 'yes' or 'no' for each:

1. They produce children with blood group ‘A’ only.
2. They produce children, some with 'O' blood group and some with 'A' blood group.

Define ecological pyramids and describe with examples, pyramids of number and biomass.

Where do transcription and translation occur inside a living cell? Briefly describe the three steps involved in the process of translation?

Which property of DNA double helix led Watson and Crick to hypothesise semi-conservative mode of DNA replication? Explain.

Describe the structure of a young anther as seen in a transverse section.