The minimum number of pigment molecules capable of acting cooperatively in a photochemical act to evolve one molecule of O₂ or to reduce one molecule of CO₂ is known as

Which hormone is found in the gaseous form?

A. Abscisic acid

B. Ethylene

C. Gibberellins

D. Auxins

In the Tetrameles - Stereospermum - Cedrela formation which of the following associations is recognised?

A. Cinnamomum - Amoora association

B. Bischofia - Dillenia association

C. Shorea - Lagerstroemia association

D. Mesua - Michelia association

Which of the following react with haemoglobin, forming methemoglobin which will not take up oxygen?

A. Nitrates

B. Nitrites

C. Carbides

D. Oxides

Internally, hydathode shows a group of loosely arranged parenchymatous cells called as

A. Epiderm

B. Epithelium

C. Ampithecium

D. Epithem