Question

Guard cells are present in the opening of

• A. Stomata
• B. Hydathode
• C. Pneumatophore
• D. Lenticle

Answer 1

Answer: (A)

Stomata

a) Stomata are small openings on the leaves which helps in transpiration and gaseous exchange. The cells of stomata are known as guard cell. The guard cells are bean or kidney-shaped in surface view so it is known as reniform which literally means kidney-shaped. The guard cells contain chloroplasts, so they can manufacture food by photosynthesis. The epidermal cells don't have chloroplast. When the stomata open for transpiration, it also allows gaseous exchange.

b) The specialized pores at vein endings of a leaf are called hydathodes. Each hydathode is made up of a group of loosely arranged achlorophyllous or colourless and parenchymatous cells called epithem. These cells help in absorbing a good percentage of inorganic and organic solutes present in the exudate.

c) Pneumatophore is an aerial root specialized for gaseous exchange. For example, in mangroves.

d) A lenticel is a porous tissue consisting of cells with large intercellular spaces in the periderm of the secondarily thickened organs and the bark of woody stems and roots of dicotyledonous flowering plants.

So, the correct answer is option A.