BIOLOGY 3 Marks Question

Role of Endothecium: Endothecium; along with the epidermis and the middle layer; provides protection to the pollens during development. Once pollen grains are mature, the three layers (including endothecium) rupture and thus facilitate the dehiscence of pollens.

Oral pills/Injections/Implants: Hormonal preparations (Progestogens or progestogens and estrogen) inhibit ovulation and implantation. "Saheli", a new oral pill is used once-a-week". It's a steroid preparation with very fewer side effects and high contraceptive value developed by CDRI in Lucknow, India.

i. The tender coconut is immature with soft and gentle solid white kernel (it is Primary Endosperm Cell) also called coconut 'meat' and the central watery fluid, free nuclear endosperm, called coconut milk( it is Primary Endosperm Nucleus) or water is highly nutritious as it contains a large number of nucleus having high amount of proteins, oils, vitamins and minerals.
ii. The seeds of pea are dicot, non-endospermic/ex-albuminous because the whole of endosperm is consumed during embryogenesis. The food is stored in massive cotyledons and there are no remnants of endosperm in the mature pea, seeds. However, in castor seeds, the whole of endosperm is not consumed completely during embryogenesis. The cotyledons are papery and the fleshy massive endosperm is present in the mature castor seeds. Seeds are known as an endospermic seed or albuminous seeds.

i. "Within a region species richness increased with increasing explored area, but only up to a limit."
ii. Very gradually impact on species diversity will be visible/species diversity will be gradually reduced/negative impact on species diversity.

i. Strong and determined personality with responsibility towards the family and respect for elders.
ii. Sex chromosomes. In human males it is XY and in the female it is XX. In birds, the male is ZZ while the female is ZW.
iii. Human females are homogametic i.e. produces only one type of gametes containing 22+X chromosomes only. Males are heterogametic and produce two types of gametes 22+X and 22+Y. It is the type of male gamete which determines the sex of the foetus. If X chromosome containing sperm fuses with the egg, it produces a female child whereas if Y chromosome containing sperm fuses with the egg, it produces a male child.

i. a. It is the follicular phase, when the endometrium regenerates through proliferation.
b. Progesterone increases (luteal phase) and maintains the endometrium essential for the implantation of the embryo.
c. If the ovum is not fertilized, the endometrium disintegrates, leading to menstruation.
ii. Estrogen is secreted by the follicle cells.
Progesterone is secreted by the corpus luteum of the ovary.

Biological oxygen demand (BOD) is the method of determining the amount of oxygen required by micro-organisms to decompose the waste present in the water supply. If the quantity of organic wastes in the water supply is high, then the number of decomposing bacteria present in the water will also be high. As a result, the BOD value will increase. Therefore, it can be concluded that if the water supply is more polluted, then it will have a higher BOD value. Out of the above three samples, sample C is the most polluted since it has the maximum BOD value of 400 mg/L. After untreated sewage water, secondary effluent discharge from a sewage treatment plant is most polluted.
Thus, sample A is secondary effluent discharge from a sewage treatment plant and has the BOD value of 20 mg/L, while sample B is river water and has the BOD value of 8 mg/L.
Hence, the correct label for each sample is:

Label	BOD value	Sample
A.	20 mg/L	Secondary effluent discharge from a sewage treatment plant
B.	8 mg/L	River water
C.	400 mg/L	Untreated sewage water