BIOLOGY 2 Marks Questions

i. Number unit volume
ii. Biomass/square kilometer (Area)
iii. Number/of square kilometer (Area)
iv. Weight/square kilometer (Area)

No population can live alone in nature. It is dependent upon other populations for various requirements. Animals get food, shelter and oxygen from plants. Plants depend upon animals for carbon dioxide, pollination, food and ploughing of soil etc.

A-Spermatogonium
B-Primary spermatocyte
C-Secondary spermatocyte
D-Spermatid
E-Spermatozoa
F-Sertoli cell

(A) - Plasmid, (B) - Nucleoid
Plasmid is used as vector to transfer the gene of interest in the host cell.

A- Insects. They are the most species-rich taxonomic group in the animal kingdom, making up more than 70 per cent of the total species found on earth. Insects are found in almost all types of habitats.
B- Fish. Among the vertebrates, fish form the largest group including both freshwater and seawater fish.

Lactobacillus are the useful bacteria present in our digestive tract, vaginal tract etc. Antibiotics taken may kill these useful bacteria along with the harmful bacteria. The killing of useful bacteria may result in the overgrowth of harmful bacteria in gut or vaginal tract that may produce toxins and cause diarrhoea or inflammation. Thus, inorder to maintain balance and optimum number of useful bacteria in the gut or vaginal tract and prevent conditions like diarrhoea or inflammation, most of the antibiotics are sold with Lactobacillus these days