Environmental Issues — BIOLOGY STD 12 Science — Question

Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

1. Both assertion and reason are true and reason is the correct explanation of assertion.
2. Both assertion and reason are true but reason is not the correct explanation of assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Assertion: Agrobaderiurm tumefaciens is called natural genetic engineer.
Reason: Agrobacterium tumefaciens infects all broad-leaved agricultural crops but does not infect cereal crops.

Fill in the blanks.
In an ecosystem dominated by trees, the pyramid (of numbers) is _________ type.

Cry-I endotoxins obtained from Bacillus thuringiensis are effective against.

1. Mosquitoes
2. Flies
3. Nematodes
4. Bollworms

A hot water spring organism ___________.

Once the pollen reaches the stigma, pollen tube traverses down the ……………… to the ovary where fertilization occurs.

The ……………… is the base of the flower to which other floral parts are attached.

_______ are the physical, chemical and biological agents that cause cancer.

Fill in the blanks:
Male and female gametes are _____________. (diploid/ haploid)

An organism which can conform __________.

The first movements of the foetus and appearance of hair on the head are observed during the _______ month of pregnancy.