Scientific Reasons From Past Papers 4

➽ Goitre is common in hilly areas.
Answer: Goitre is common in hilly areas because there is deficiency of Iodine in the water.

➽ Detergents are better cleaning agents.
Answer: A detergent consists of hydrophilic and hydrophobic ends. In case of dirt the detergent pushes the dirt off the wet surface of the fabric. The washing machine provides the agitation.

➽ Decomposers are important for life.
Answer: Decomposers break down animal waste and dead organisms in order to get energy and release free nutrients back into the ecosystem.
OR
Decomposers break down organics into nutrients, which can be used by living organisms to create new life.

➽ Places near sea are cooler in summer.
Answer: Sea water keeps the temperature moderate. In the summer season the places located near sea are cooler due to the lower temperature of water.

➽ Colour blindness is more common in men than women.
Answer: Women have the sex chromosomes XX, while men have the chromosomes XY. The gene for normal colour vision is found on the X-chromosome. If a woman has one X-chromosome with the gene and one without it, she will not be colour blind. On the other hand, a man with an X- chromosome that is missing the gene has no 'backup'. He will definitely be colour blind. Colour blind women have both X-chromosomes missing the colour vision gene. This is less probable mathematically than having just one X-chromosome missing the gene.