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

Classify the following contraceptive measures into different methods of birth control.

1. Saheli.
2. Tubectomy.
3. Vasectomy.
4. Condoms.
5. Diaphragms.
6. Cervical caps.

Three water samples namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant were subjected to BOD test. The samples were labelled A, B and C; but the laboratory attendant did not note which was which. The BOD values of the three samples A, B and C were recorded as 20mg/L, 8mg/L and 400mg/L, respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?

A dihybrid heterozygous round, yellow seeded garden pea was crossed with a double recessive plant.

1. What type of cross is this?
2. Work out the genotype and phenotype of the progeny.
3. What principle of Mendel is illustrated through the result of this cross?

Describe the role of Agrobacterium tumefaciens in transforming a plant cell.

Write a short note on Apomixis and polyembryony.

Explain the following salient features of a DNA molecule:

1. Complimentarity of base pairs of its two chains.
2. Antiparallel polarity of the two chains.

During a school trip to 'Rohtang Pass', one of your classmate suddenly developed 'altitude sickness'. But, he/she recovered after some time.

1. Mention one symptom to diagnose the sickness.
2. What caused the sickness?

Write a short note on advantages of seeds.

Name the scientist who had used the set-up shown below. Write the purpose of 'a' in the set-up and the conclusion the scientist arrived at.