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52

What is secondary metabolism?

Explanation

Secondary metabolism (also called specialised metabolism) is a term for pathways and metabolites are small molecule produced by metabolism that are not absolutely required for the survival of the organism.

In case of plant, metabolites aid in the growth and development of plants. It also facilitates the primary metabolism.

53

$$ \text { Drugs and alcohol give short-term 'high' and long-term 'damages'. } $$

Explanation

Curiosity, need for adventure and excitement and experimentation, constitute common causes, which motivate youngsters towards drug and alcohol use.

The frequent use of drugs/alcohols drive people to take them even when these are not needed, or even their use becomes self-destructive.

Short-term effects of drugs/alcohols

A relaxing effect

Lowered inhibitions

Slow reflexes

Reduced coordination

Reduced tension

Poor concentration

Slow reaction time

Slower brain activity

Sensations and perceptions that are less clear

Long-term effects of drugs/alcohols

Disrupts normal brain development

Liver damage and cirrhosis of the liver

Brain cells die, decreasing brain mass

Stomach and intestinal ulcers and destroyed organs

Blood pressure increases, causing heart disease, heart attack or stroke

Male sperm production decreases

Lower levels of iron and vitamin-B, causing anaemia

Alcoholism

Death and

Fetal alcohol syndrome in unborn children

54

Diseases like dysentery, cholera, typhoid, etc., are more common in over crowded human settlements. Why?

Explanation

Dysentery, cholera and typhoid are more common in crowded settlements because these are infectious diseases and spread from person to person contact. Water gets contaminated with the excreta of infected people and causes the spread of infection to other people.

55

From which plant cannabiniods are obtained? Name any two cannabinoids. Which part of the body is effected by consuming these substances?

Explanation

Cannabinoids are obtained from the inflorescence of the plant Cannabis sativa. Marijuana, hashish, charas, ganja are some cannabinoids. These chemicals interact with cannabinoid receptors of the body, mainly present in the brain. Cardiovascular system of the body is effected adversly by consuming these substances.

56

In the metropolitan cities of India, many children are suffering from allergy/asthma. What are the main causes of this problem. Give some symptoms of allergic reactions.

Explanation

In metropolitan cities life style is responsible in lowering of immunity and sensitivity to allergens. More polluted environment like dust in surroundings increases the chances of allergy in children. Some symptoms of allergic reactions are sneezing, watery eyes, running nose and difficulty in breathing.