Organisms and Populations — BIOLOGY STD 12 Science — Question

The ___________ is measured as biomass or number per unit area.

_______ is an autonomously replicating, circular, extra-chromosomal DNA in bacterial cells.

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.

The offspring of ____________ animals are vulnerable to predators.

is any attribute of an organism (morphological, physiological and behavioural) that enables it to live and reproduce in the given area.

In oviparous animals like reptiles and birds, the fertilised egg is covered by a ____________ shell and laid in a safe place.

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

_______ mosquitoes are the vectors of dengue and chikungunya.

Fossils of ______ were discovered in Java.

Fill in the blanks:
Humans reproduce _____________. (asexually/ sexually)