Question

16.
Read the following and answer any four questions from 16(i) to 16(v) given below:
- For plants, herbivores are the predators. Nearly 25 per cent of all insects are known to be phytophagous (feeding on plant sap and other parts of plants). The problem is particularly severe for plants because, unlike animals, they cannot run away from their predators. Plants therefore have evolved an astonishing variety of morphological and chemical defences against herbivores. Thorns (Acacia, Cactus) are the most common morphological means of defence. Many plants produce and store chemicals that make the herbivore sick when they are eaten, inhibit feeding or digestion, disrupt its reproduction or even kill it. You must have seen the weed Calotropis growing in abandoned fields. The plant produces highly poisonous cardiac glycosides and that is why you never see any cattle or goats browsing on this plant. A wide variety of chemical substances that we extract from plants on a commercial scale (nicotine, caffeine, quinine, strychnine, opium, etc.,) are produced by them actually as defences against grazers and browsers.

4



i.
Thorns in the cactus are the
Physical means of defence
Physiological means of defence
Behavioral means of defence
morphological means of defence


ii.
Calotropis have mechanism of defence because of
Thorns
Cardiac glycosides
Nicotine
Alkaloid


iii.
Phytophagus means
feeding on plant sap
feeding on Animal sap
feeding on Cactus
feeding on plant like calotropis


iv.
Defence mechanisms are evolved in plants or animals to protect themselves against
Competition
Commensalism
Parasitism
Predators


v.
Which one is not a defence mechanism of plants –
herbivore sick when they are eaten
inhibit feeding
disrupt its reproduction
Plants are colorful

​

Answer 1

Answer:

t8ccuxy

G 6vuc

h.n

please

tinnava

em chesthunnav

hcjvHhv8 is vyof6p2ofuraiv6