Question 1

Which of the following statements does not apply to reverse osmosis?

Accepted Answer

Reverse osmosis is not an active process. A process (in organisms) is considered active when its completion requres energy in from of ATP. And as reverse osmosis dose not consume ATP, it is a passive process, though external pressure is applied in order to carry out osmosis in a reverse direction (lower to higher). Rest of the options are ture for reverse osmosis.

Question 2

Which one of the following will not directly affect transpiration?

Accepted Answer

Chlorophyll content will not affect the rate of transpiration. Options (a), (b) and (c) all affect the rate of transpiration. (a) Temperature increases the rate of transpiration. (b) Light quality and intensity also affect the rate of this phenomenon. (c) Wind speed higher the wind speed, more will be the rate of transpiration.

Question 3

The lower surface of leaf will have more number of stomata in a

Accepted Answer

(a) In dorsiventral leaf, the number of stomata will be more on lower surface. This feature enhances gas exchange between leaf surface and the atmosphere for the processes of photosynthesis and respiration. Whereas in isobilateral leaf, stomata are uniformly distributed on both the surfaces.

Question 4

The process of guttation takes place

Accepted Answer

The process of loss of water in the form of liquid drops from the edges of leaves or the tips of veins through hydathodes is known as guttation.This process usually happens in herbaceous plants when the humidity is and the root pressure is high and the rate of transpiration is low.

Question 5

When a plant undergoes senescence, the nutrients may be

Accepted Answer

Senescence is the programmed death of a plant. Translocation of nutrients to different parts of the plant are withdrawn at the time of senescence.

Question 6

The form of sugar transported through phloem is

Accepted Answer

Sucrose a disaccharide sugar is transported through phloem. It comprises of 2 units of glucose joined by α−1−4 linkage. It is the most inactive form of sugar so used in the transport of food.Glucose because of presence of CHO group is reactive sugar.Fructose is founds in fruits and ribose is present in nucleic acids.

Question 7

Water potential of pure water at standard temperature is equal to

Accepted Answer

(c) Water potential of pure water at standard temperature is zero. It is the highest value of water potential.

Question 8

Choose the correct option mycorrhiza is a symbiotic association of fungus with root system which helps in A. absorption of water B. mineral nutrition C. translocation D. gaseous exchange

Accepted Answer

Mycorrhiza associated with roots of plants helps in both absorption of water and minerals from the soil. The other options are incorrect.

Question 9

Which of the following is an example of imbibition?

Accepted Answer

(c) Swelling of seed in soil is an example of imbibition. Imbibition is a type of diffusion process along the concentration gradient enabling the solid to absorb water and increase in volume. When seed is put in the soil it absorbs water which activate enzymes present in seed and this induces the seed germination. The other options, i.e., uptake of water by root hair is an example of absorption, exchange in of gases stomata is an example of diffusion and opening of stomata is an example of turgor pressure or turgidity.

Question 10

Based on the figure given below which of the following statements is not correct?

Accepted Answer

Movement of water will take place from chamber A to B. It is not the solute which will move from chamber A to B. The is because osmosis is a process in which solvent molecules moves from a region of higher concentration to a region of lower concentration through a semi-permeable membrane.

Question 11

Match the followings and choose the correct option.

Accepted Answer

(a) The correct matched sequence of the two columns is as follows. Leaves  Seed  Roots  Aspirin  Plasmolysed cell ​−−−−−​ Transpiration  Imbibition  Absorption  Anti-transpirant  Negative osmotic potential ​

Question 12

Mark the mismatched pair.

Accepted Answer

(a) Amyloplasts are the colourless plastids which store starch but not the protein granules. Other pairs are correctly matched.

Question 13

In a passive transport across a membrane. When two protein molecules move in opposite direction and independent of each other, it is called as ......... .

Accepted Answer

Antiport This process facilitates transport of molecules in both the directions across the membrane and their movement is independent of each other.

Question 14

Identify the process occurring in I, II and III

Accepted Answer

I. Uniport In this process, there is movement of a molecule across a membrane, i.e., of other molecules.II. Antiport In this process, there is a movement of two types of molecules in opposite direction.III. Symport In this process, there is a movement of more than one molecule across the membrane in the same direction, at one time.

Question 15

A flowering plant is planted in an earthen pot and irrigated. Urea is added to make the plant grow faster, but after sometime the plant dies. This may be due to ......... .

Accepted Answer

The plant dies due to exosmosis. As the solution outside the plant is an hypertonic solution, and the plant cell are hypotonic in nature, so there is a gradual movement of water from plant cell to outside urea solution leading to plasmolysis of root cells and plant dies gradually.

Question 16

Absorption of water from soil by dry seeds increases the ......... , thus helping seedlings to come out of soil.

Accepted Answer

Due to imbibition of water by seed materials (starch and protein), pushes the seedlings out of the soil, thus the seed swells and imbibition pressure increases inside the seed, which contributing for germination of seeds.

Question 17

Water moves up against gravity and even for a tree of 20 m height, the tip receives water within two hours. The most important physiological phenomenon which is responsible for the upward movement of water is ......... .

Accepted Answer

Transpiration pull is the physiological phenomenon which is responsible for the upward movement of water in trees of height up to 20m. As the water molecules transpire from stomata, it pulls water molecules up ward to the leaf from the continuous chain of water molecules carried by xylem. This transpiration from leaf creates a pressure gradient between the atmosphere and sub-stomatal cavity and intercellular spaces of leaf. This gradient is transferred to photosynthetic cells and then on to xylem of leaf vein. It results in a force called ‘‘transpiration pull’’ that can lift water upto 130m high, through a xylem column.

Question 18

The plant cell cytoplasm is surrounded by both cell wall and cell membrane. The specificity of transport of substances are mostly across the cell membrane, because ......... .

Accepted Answer

The transport takes place by the cell membrane because cell membrane is semi-permeable and composed of lipids that are arranged in bilayer structure along with proteins and carbohydrate. The lipid soluble molecules pass readily across lipid bilayer of cell membrane whereas movement of other molecules of small size is facilitated by porins, pores made up of proteins. While cell wall does not helps in transport of substances because it. Cell wall is basically a non-living rigid structure forming outer covering over plasma membrane and it provides shape, mechanical strength and protection to the plant cell from damages and infection.

Question 19

The C4​ plants are twice as efficient as C3​ plants in terms of fixing CO2​ but lose only …… as much water C3​ plants for the same amount of CO2​ fixed.

Accepted Answer

Half, The evolution of the C4​ or plants photosynthetic system is probably one of the strategies for maximising the ability of CO2​ while minimising water loss. C4​ plants are twice as efficient as C3​ plants in terms of fixing carbon in the form of glucose, but lose only half as much water as aC3​ plant for the same amount of C2​ fixed.

Question 20

Movement of substances in xylem is unidirectional while in phloem it is bidirectional. Explain

Accepted Answer

Xylem is involved in the one way transport of water and minerals from soil to root → stem → leaves. Several forces act in this mechanism like imbibition, root pressure and finally transpiration pull. There is continuous loss of water at the body surface of plants. Thus, it is a unidirectional process.Phloem's main function is to transport food from source to sink where source implies with the part of plant responsible for synthesising food and sink to those parts and organs that needs or consumes food for their growth and development. These source and sink parts of a plants may vary in different phases of its growth, thus the food need to travel in both upwards and downward direction. So, phloem shows bidirectional movement of substances.

Chapter 11 : Transport in Plants