Reproduction in Lower and Higher Animals — BIOLOGY STD 12 Science — Question

1. Explain sex determination in humans.
2. How do human males with 'XXY' abnormality suffer?

During an excursion to a botanical garden, the teacher shows an old tree, which was on the verge of extinction. As soon as the teacher advanced with the students, some enthusiastic students climbed up the tree and started cutting the branches, collecting its leaves as precious collection. Rajesh instead took photographs of the tree from various angles. The boys mocked at Rajesh while the teacher appreciated him.

1. How can biodiversity be conserved?
2. What international initiatives were taken to conserve biodiversity?
3. What values did Rajesh possess?

Define 'genomics'. Give any 'two' applications of it.

Recombinant DNA technology is of great importance in the field of medicine. With the help of a flow chart, show how this techonolgy has been used in preparing genetically engineered human insulins.

"Pollen grains in wheat are shed at 3-celled stage while in peas they are shed at 2-celled stage." Explain. Where are germ pores present in a pollen grain?

What is colostrum? How is milk production hormonally regulated?

Describe the process of Parturition in humans.

In the light of Griffith's experiment, explain the action of two strains of Diplococcus pneumoniae and give his conclusion.

1. Write the characteristic features of anther, pollen and stigma of wind pollinated flowers.
2. How do flowers reward their insect pollinators? Explain.

1. Name the kind of diseases/ disorders that are likely to occur in humans if
   1. Mutation in the gene that codes for an enzyme phenyl alanine hydrolase occurs,
   2. There is an extra copy of chromosome 21,
   3. The karyotype is XXY.
2. Mention any one symptom of the diseases/ disorders named above.