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

Identify A, B, C and D in the following table:

Scientific name of the source plant	Drug	Harmful effects/ Human body part affected
Papaver somniferum	A	Depressant/ slows body functions
Cannabis sativa	Cannabinoids	B
Erythroxylon coca	C	D

Differentiate between the roles of B-lymphocytes and T-lymphocytes in generating immune response.

For desirable cloning, vector must have origin of replication- discuss your answer.

Answer the following:

1. Highlight the role of thymus as a lymphoid organ.
2. Give the name of the cells that are released from the above mentioned gland. Mention how they help in immunity?

Differentiate between albuminous and non-albuminous seeds, with an example for each.

The schematic representation given below shows a DNA strand and two types of mutations in the DNA strand.

(i) Identify the type of mutation exhibited in I and II.
(ii) Which of the above mutation is more harmful? Give reason.

Recall the experiment done by Frederick Griffith. If RNA, instead of DNA was the genetic material, would the heat killed strain of Streptococcus have transformed the R-strain into virulent strain? Explain your answer.

Identify the odd one out in each of the following sets:

1. Rete testis, vas deferens, isthmus, epididymis.
2. Seminal vesicles, ampulla, prostate, bulbourethral glands.

Categorise the following plants into hydrophytes, xerophytes, halophytes and mesophytes. Write the type of plant against the following examples.

1. Salvinia.
2. Opuntia.
3. Rhizophora.
4. Mangifera.