Human Reproduction — BIOLOGY STD 12 Science — Question

What is oogenesis? Give a brief account of oogenesis.

Restriction enzymes are found in bacteria (and other prokaryotes). They recognize and bind to specific sequences of DNA, called restriction sites. Each restriction enzyme recognizes just one or a few restriction sites.
When it finds its target sequence, a restriction enzyme will make a double-stranded cut in the DNA molecule.
i. Write the palindromic nucleotide sequence for the following DNA segment.
5'-GAATTC-3'
ii. Name the restriction endonuclease that recognises this sequence.
iii. How are sticky ends produced? Mention their role.

1. Which of the above represents the increase or decrease of population?
2. If N is the population density at time t, then what would be its density at time (t + 1)? Give the formula.
3. In a barn there were 30 rats. 5 more rats enter the barn and 6 out of the total rats were eaten by the cats. If 8 rats were born during the time period under consideration and 7 rats left the barn, find out the resultant population at time (t + 1).
4. If a new habitat is just being colonized, out of the four factors affecting the population growth, which factor contributes the most?

List 10 modern day animals and using the various resources available link it to a corresponding ancient fossil. Name both of them.

(i) Define contact inhibition.
(ii) Explain the difference between benign tumors
and malignant tumors.
(iii) Write any one cause of cancer.

Microbes can be used to decrease the use of chemical fertilisers and pesticides. Explain how this can be accomplished.

Explain fluid mediated immunity and cell mediate immunity in detail.

Write a short note on pyramid of numbers and pyramid of biomass.

Describe the following: Bioreactor