Flow of energy in an ecosystem is always

In an ecosystem, the 10% of energy available for transfer from one trophic level to the next is in the form of

Organisms of a higher trophic level which feed on several types of organisms belonging to a lower trophic level constitute the

Excessive exposure of humans to U V-rays results in

(i). damage to immune system

(ii). damage to lungs

(iii). skin cancer

(iv). peptic ulcers

In the following groups of materials, which group (s) contains only non-biodegradable items?

i. Wood, paper, leather

ii. Polythene, detergent, PVC

iii. Plastic, detergent, grass

iv. Plastic, bakelite, DDT