BIOLOGY 2 Marks Questions

During treatment (after adding small amount of inoculum) primary effluent is constantly agitated mechanically and air is pumped into it.
- This allows the vigorous growth of useful microbes into flocs.
- The microbes consume the major part of the organic matter in the effluent.
- It reduces the BOD of the effluent.
- The effluent is then passed into settling tank where the bacterial flocs are allowed to sediment.
- A Major part of the activated sludge is pumped into an aerobic sludge digester.

Enzyme produced by Streptococcus bacterium is streptokinase.
It is used as a 'clot buster' for removing clots from the blood vessels of patients who have undregone myocardial infraction leading to heart attack.

1. A-Spermatogonia,
B-Interstitial cells
C-Spermatozoa.
2. A-Spermatogonia produces a spermatogonium (plural: spermatogonia) is an undifferentiated male germ cell. Spermatogonia undergo spermatogenesis to form mature spermatozoa in the seminiferous tubules of the testes.
D-Sertoli cells provide nutrition to sperms.

i. A-AUG, B-UAA/UAG/UGA
ii. AUG codes for methionine. UAA/UAG/UGA does not code for any amino acid, but brings about termination of polypeptide
synthesis.
iii. In the large subunit of ribosome, there are two sites in which subsequent amino acids bind to and come close enough for the formation of peptide bond. It is catalysed by the enzyme called peptidyl transferase.

Micro-organisms play an important role in the biological treatment of sewage as these microbes use the organic matter present in wastewater and reduce the BOD (Biological oxygen demand). BOD is the amount of oxygen that aerobic bacteria utilise to break down biodegradable organic matter into end products such as water and Carbon dioxide.