Sexual Reproduction in Flowering Plants — BIOLOGY STD 12 Science — Question

What is pregnancy? Write the name of pregnancy maintaining hormone.

With the help of any two suitable examples explain the effect of anthropogenic action on organic evolution.

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.

Given below is the representation of amino acid composition of the relevant translated portion of b-chain of haemoglobin, related to the shape of human red blood cells.

1. Is this representation indicating a normal human or a sufferer from certain related genetic disease? Give reason in support of your answer.
2. What difference would be noticed in the phenotype of the normal and the sufferer related to this gene?
3. Who are likely to suffer more from the defect related to the gene represented – the males, the females or both males and females equally? Andwhy?

What is ADA deficiency and how can it be cured?

Draw a well labelled diagram of mature graafian follicle.

Nikhil goes with his family for dinner and insists on sitting in the non-smoking area to which his father (who is a heavy smoker) obiects.

Draw a schematic transverse section of a mature anther of an angiosperm. Label its epidermis, middle layers, tapetum, endothecium, sporogenous tissue and the connective.

Draw the diagram of a mature embryo sac and show its 8-nucleate, 7-celled nature. Show the following parts: antipodals, synergids, egg, central cell, polar nuclei.

Humans benefit from diversity of life. Give two examples.