Questions

Read the passage carefully and choose the best answer to each question out of the four alternatives.

Genetic variation is the cornerstone of evolution, without which there can be no natural selection, and so a low genetic diversity decreases the ability of a species to survive and reproduce, explains lead author Yoshan Moodley, Professor at the Department of Zoology, University of Venda in South Africa.

Two centuries ago, the black rhinoceros – which roamed much of sub Saharan Africa – had 64 different genetic lineages; but today only 20 of these lineages remain, says the paper. The species is now restricted to five countries, South Africa, Namibia, Kenya, Zimbabwe and Tanzania. Genetically unique populations that once existed in Nigeria, Cameroon, Chad, Eritrea, Ethiopia, Somalia, Mozambique, Malawi and Angola have disappeared. The origins of the 'genetic erosion' coincided with colonial rule in Africa and the popularity of big game hunting. From the second half of the 20th century, however, poaching for horns has dramatically depleted their population and genetic diversity, especially in Kenya and Tanzania.

From the second half of the 20th century what has caused a dramatic fall in black rhinoceros population?

A radioactive substance has a half life of four months, three-fourth of the substance would decay in

Botany is also known as

By default, a real number is treated as a

Improve the bracketed part of the sentence.

It also indicates the caveats and failure modes in the model need to be improved before (been used independently).

The isotopes of chlorine with mass number 35 and 37 exist in the ratio of

When a gas is turned into a liquid, the process is called

The source of energy of the sun is