Questions

A greenhouse gas is a gas in an atmosphere that absorbs and emits radiant energy within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. 

Carbon dioxide is a main greenhouse gas, found in car exhaust pipes.
Methane and nitrous oxide is another type of greenhouse gas.

Oxygen is the only clean gas out there because we need it to survive. Therefore, the only gas that is not a greenhouse gas is Oxygen.

Trypanosoma is a protozoan animal. It lives as a parasite in the blood and later invades the cerebrospinal fluid to cause the sleeping sickness. This parasite is transmitted by the Tsetse fly.

Genetic drift or allelic drift is the change in the relative frequency in which a gene variant (allele) occurs in a population due to random sampling and chance.

When is genetic drift a major factor in evolution is

* When there is low gene flow.

* When there is no selective pressure.

* When there is a bottleneck.

Abolition and hallucinations is the pair that consists of negative symptoms of schizophrenia.

Expedite means making an action fast or sooner i.e, to accomplish a work as quickly as possible.

Hence, halt means stop and it is opposite of Expedite.

We know that, preceeded means to come before. 

Hence, the given sentence, preceded in death means that person had died before this person.

For example :: Rahul preceeded Ravi in death, means Rahul died before Ravi.

The color of giraffe's tongue is purple or bluish to prevent it from sunburn as it lives in tropical regions.