Life Process and Nutrition - Free MCQ Practice Test with solutions, UPSC

Mesophyll cells are a type of ground tissue found in the plant's leaves. Mesophyll cells are specialized for photosynthesis. These cells in the middle of the leaf contain many chloroplasts, the organelles that perform photosynthesis .

The correct answer is Each stoma is guarded by guard cell

The tissues of a leaf that are located in between the layers of epidermis and carry on photosynthesis, consisting of the palisade layer and the spongy parenchyma. Most mesophyll cells contain chloroplasts.

A sunken stomata is a stomata in a small pit, which protects the escaping water vapor from air currents, decreasing water loss from the leaf. Sunken stomata are commonly found in plants in arid environments as one of their adaptations to preserve water. Plants with sunken stomata often have fewer stomata in general than plants.
Sunken stomata are a feature of many plants in deserts and other dry environments. This plants are generally reffered to as xerophytes. 

Stomata allow a plant to take in carbon dioxide, which is needed for photosynthesis. They also help to reduce water loss by closing when conditions are hot or dry. Stomata look like tiny mouths which open and close as they assist in transpiration.

The stomata control gas exchange in the leaf. Each stomata can be open or closed, depending on how turgid it's guard cells are. In the light, the guard cells absorb water by osmosis, become turgid and the stomata opens. In the dark, the guard cells lose water, become flaccid and the stomata closes.

Usually the lower surface of a dicot leaf has a greater number of stomata while in a monocot leaf they are more or less equal on both surfaces. In most of the floating plants, stomata are found only on the upper epidermis.

Stomata of monocot and dicot plants are kind of pores that occur in leaves and stem, facilitating the gas exchange. Transpiration also occurs through stomata. Monocots contain dumbbell-shaped guard cells, surrounding their stomata.

In Hydrilla, the function of stomata is the same as in the case of terrestrial plants i.e. transpiration and exchange of gases like CO₂ or O₂ but the only thing is that stomata are present more on the upper surface of the floating leaves of the plants as compared to the lower side of the leaves is submerged in water.

Correct Answer :- d

Explanation : Stomatal responses to blue and red light were compared in leaves of Xanthium pennsylvanicum (which contain starch in their guard cells) and in onion leaves (which are devoid of starch). Blue light was found to be more effective than red in opening stomata in both species.

The correct answer is B as photophosphorylation is the production of ATP from ADP and H
3PO4 in presence of ligh1950609t and chlorophyll-a during the photochemical phase of photosynthesis. 
During cyclic photophosphorylation, ATP is produced and in non-cyclic photophosphorylation, ATP and NADPH2 are produced.

The correct answer is C as Photosynthesis proceeds in sequence of light phase and dark phase.

Light energy is converted to chemical energy when a Photochemically excited special chlorophyll molecule of thr photosynthetic reaction center loses an electron, undergoing an oxidation reaction.

Photosynthetic pigments are located in the Grana. The green pigment chlorophyll is located within the thylakoid membrane, and the space between the thylakoid and the chloroplast membranes is called the stroma.

The correct option is A.
In a process called photolysis ('light' and 'split'), light energy and catalysts interact to drive the splitting of water molecules into protons (H+), electrons, and oxygen gas.

The dark reaction occurs in the stroma of the chloroplast, where they utilize the products of the light reaction. 

The correct answer is B  as Bacterial photosynthesis is mostly similar to the normal plant synthesis.
Similarly, the bacterial photosynthesis also uses the hydrogen molecules for the photosynthesis reactions,just like the normal plant photosynthesis.
And the donor of hydrogen in the bacterial photosynthesis is the hydrogen sulphide.
 

The liver doesn't secrete any enzymes. The liver secretes bile. In the presence of bile, lipase, an enzyme breaks down the fat into smaller units. Bile is stored on the gall bladder. 

There are three pairs of major Salivary glands :- the parotid glands, the submandibular glands and the sublingual glands.

Liver is the largest gland in human body. It carries out many functions such as secretion of bile juices for decomposition of lipids and vitamins, preparation of proteins for blood plasma that enables blood clotting and also detoxification.