OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER www wisedane
OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER www. wisedane. com
BIOLOGY TRANSPORATION IN PLANTS SET 2 MCQ’s www. wisedane. com
Q 1. Transport of food material in higher plants takes place through A. Tracheid B. Transfusion tissue C. Companion cells D. Sieve elements www. wisedane. com
ANSWER (D) EXPLANATION A. The food manufactured in the leaves is translocated upwards, downwards and laterally to all parts of the plant through the phloem. B. The phloem also conducts some other substances such as amino acids. The conducting cells of the phloem are cylindrical cells called sieve elements, which have sieve like partitions at both ends. These partitions are called sieve plates. www. wisedane. com
Q 2. Guttation is the result of A. Diffusion B. Root pressure C. Osmosis D. Transpiration www. wisedane. com
ANSWER (B) EXPLANATION Ø The loss of extra water in liquid drops from margins of leaves of herbaceous plants when root pressure is high and transpiration is low. Ø Due to this, root pressure is developed and water is pushed out through specialized pores at vein endings called hydathodes therefore guttation is not due to the activity of hydathodes but due to root pressure www. wisedane. com
Q 3. Hydathodes are also called A. guard cells B. sunken stomata C. water stomata D. subsidiary cells www. wisedane. com
ANSWER (C) EXPLANATION Ø Hydathodes are made of a group of living cells with numerous intercellular spaces filled with water, but few or no chloroplasts, and represent modified bundle-ends. These cells called epithem cells open out into one or more sub-epidermal chambers. Ø They, in turn, communicate with the exterior through an open water stoma or open pore. The water stoma structurally resembles an ordinary stoma, but is usually larger and has lost the power of movement. Hence called water stomata. www. wisedane. com
Q 4. Graham’s Law is correlated with A. Osmosis B. Osmoregulation C. Diffusion D. Adsorption www. wisedane. com
ANSWER (C) EXPLANATION Ø Graham's law states that the rate of effusion or of diffusion of a gas is inversely proportional to the square root of its molecular weight. www. wisedane. com
Q 5. If water enters in a cell, the pressure exerted by its swollen protoplast is A. Osmotic pressure B. Diffusion pressure deficit C. Turgor pressure D. Imbibition www. wisedane. com
ANSWER (C) EXPLANATION A. The water pressure inside plant cells is called turgor pressure, and it is maintained by a process called osmosis. Osmosis is the movement of water across a differentially permeable membrane from a place where water concentration is higher to one where the concentration is lower. B. Turgor pressure pushes the plasma membrane against the cell wall of plant, bacteria, and fungi cells as well as those Protist cells which have cell walls. C. It causes plant cells to remain turgid, enabling the plant to stand upright without wilting. www. wisedane. com
Q 6. Munch hypothesis is based on A. Translocation of food due to imbibition force. B. Translocation of food due to TP gradient and imbibition force. C. Translocation of food due to Turgor Pressure (TP) gradient. D. None of these www. wisedane. com
ANSWER (C) EXPLANATION Ø The Pressure Flow Hypothesis, also known as the Mass Flow Hypothesis, is the best-supported theory to explain the movement of sap through the phloem. Ø It was proposed by Ernst Munch, a German plant physiologist in 1930 which is based on the translocation of food due to Turgor Pressure (TP) gradient www. wisedane. com
Q 7. Attraction of water molecules to polar surfaces is known as A. Cohesion B. Capillarity C. Surface tension D. Adhesion www. wisedane. com
ANSWER (D) EXPLANATION Ø Cohesion holds hydrogen bonds together to create surface tension on water. Ø Since water is attracted to other polar molecules, adhesive forces pull the water toward other molecules. www. wisedane. com
Q 8. Cohesion theory of water movement in plants was put forth by A. Henry Dixon B. F. F. Blackman C. Melvin cycle D. Hans. A. Krebs www. wisedane. com
ANSWER (A) EXPLANATION Ø The cohesion–tension theory of sap ascent was put forward by Henry Dixon. It explains how water is pulled up from the roots to the top of the plant. Ø Evaporation from mesophyll cells in the leaves produces a negative water potential gradient that causes water and minerals to move upwards from the roots through the xylem www. wisedane. com
Q 9. The amount of water held by the soil after drainage is A. Mineral water B. Soil water C. Field capacity D. Gravitational capacity www. wisedane. com
ANSWER (C) EXPLANATION Ø Field Capacity is the amount of soil moisture or water content held in the soil after excess water has drained away and the rate of downward movement has decreased. Ø This usually takes place 2– 3 days after rain or irrigation in pervious soils of uniform structure and texture. www. wisedane. com
Q 10. Water available for plants in soil A. Capillary water B. Hygroscopic water C. Gravitational water D. Chemically bound water www. wisedane. com
ANSWER (A) EXPLANATION Ø Capillary water is the water that remains in the soil after the water drains; it permits plants to survive through periods of drought. The Tree solution notes that capillary water is equally as important as condensation or rain. Ø The construction of the "Groasis waterboxx" utilizes capillary water; it uses a cylinder in the middle of this waterboxx. The roots of either a tree or a plant can be placed inside this instrument in as little as 5 cm of soil. After only one day, root hairs begin to develop in the undisturbed soil, where capillary water is located. The large amount of capillary water assists the tree or plant to begin growing sooner. www. wisedane. com
Q 11. The most widely accepted theory for ascent of sap in trees is (a) capillarity (b) role of atmospheric pressure (c) pulsating action of living cell (d) transpiration pull and cohesion theory of Dixon and Jolly. www. wisedane. com
ANSWER (D) EXPLANATION: Ø Transpiration pull cohesion theory for ascent of sap in trees is most widely accepted. This concept was proposed by Dixon and Joly, 1884. Ø It is based up on three basic assumptions which are cohesion in between water molecules, continuity of water column and transpiration pull. www. wisedane. com
Q 12. Guttation is mainly due to A. root pressure B. osmosis C. transpiration D. imbibition. www. wisedane. com
ANSWER (A) EXPLANATION: Ø The loss of water through water stomata (hydathodes) is called as guttation. Guttation occurs when transpiration rate is very low as compared to rate of water absorption. Ø Due to this, root pressure is developed and water is pushed out through specialized pores at vein endings called hydathodes therefore guttation is not due to the activity of hydathodes but due to root pressure. www. wisedane. com
Q 13. When water enters in roots due to diffusion, is termed as A. osmosis B. passive absorption C. endocytosis D. active absorption. www. wisedane. com
ANSWER (C) EXPLANATION: Ø Water is absorbed from soil by root system and mainly by root tips. There are two independent mechanisms of water absorption in plants active water absorption and passive water absorption. Ø In active water absorption water is absorbed by the activity of the root itself. In passive water absorption transpiration pull is responsible for absorption of water. Ø According to this theory loss of water from mesophyll cells of leaves in transpiration decreases their T. P. and hence increases their D. P. D. or S. P. As a result of their increased DPD, they absorb water from adjacent xylem vessels of leaves. Ø This xylem of the leaves is in continuation with xylem of stem and roots and hence this pull is transmitted downwards. The pull or tension is removed only when water is absorbed through root hair and this is passive water absorption. Thus transpiration pull is responsible for passive water absorption. www. wisedane. com
Q 14. The movement of ions against the concentration gradient will be A. active transport B. osmosis C. diffusion D. all of the above www. wisedane. com
ANSWER (C) EXPLANATION: Ø Active transport involves movement of materials across the membrane against the concentration gradient of the solute particles. Ø It requires energy in the form of ATP and carrier molecules. www. wisedane. com
Q 15. The +ve value of ? P is called A. Osmotic pressure B. Root pressure C. Turgor pressure D. Imbibition pressure www. wisedane. com
ANSWER (C) EXPLANATION: Ø The water pressure inside plant cells is called turgor pressure, and it is maintained by a process called osmosis. Turgor pressure pushes the plasma membrane against the cell wall of plant, bacteria, and fungi cells as well as those protist cells which have cell walls. Ø It causes plant cells to remain turgid, enabling the plant to stand upright without wilting. www. wisedane. com
Q 16. For keeping stomata open, besides K+ ions the guard cells require a constant supply of A. ABA B. ATP C. Organic acid D. Protons www. wisedane. com
ANSWER (B) EXPLANATION: Ø The mechanism namely the opening and closing of stomata depends upon the turgor pressure in the guard cells. When the guard cells are turgid, the stoma opens and when the guard cells lose water, stoma closes. Ø opening of stomata occurs due to the influx of K+ ions into the guard cells. The source of K+ ions are the neighbouring subsidiary and epidermal cells, thereby increasing the concentration from 50 m. M to 300 m. M in guard cells. www. wisedane. com
Q 17. Water tightly held to soil particles is called A. Bound water B. Capillary water C. Hygroscopic water D. Run away water www. wisedane. com
ANSWER (C) EXPLANATION: A. Water absorbed from the atmosphere and held very tightly by the soil particles, so that it is unavailable to plants in amounts sufficient for them to survive. This is called hygroscopic water. B. This is achieved through either absorption or adsorption with the absorbing or adsorbing substance becoming physically changed. www. wisedane. com
Q 18. Force for passive water absorption develops in A. Xylem B. Aerial parts C. Root D. Root hairs www. wisedane. com
ANSWER (B) EXPLANATION: Ø Aerial parts of plant are parts which are completely exposed in air. Aerial parts of plants are the parts above ground where force for passive water absorption occurs. Ø The opposite would be the parts under the ground: roots, tubers, corms, bulbs etc. Potency of various parts of plants will vary from species to species. www. wisedane. com
Q 19. Ascent of sap is A. Upward movement of water in the plant B. Downward movement of organic nutrients C. Upward and downward movement of water in the plant D. Redistribution of inorganic substances in the plant www. wisedane. com
ANSWER (D) EXPLANATION: Ø The ascent of sap in the xylem tissue of plants is the upward movement of water and minerals from the root to the crown, distributing it to entire plant. Ø Xylem is a complex tissue consisting of living and non-living cells. The conducting cells in xylem are typically non-living and include, in various groups of plants, vessels members and tracheid. www. wisedane. com
Q 20. In xylem, the ascent of sap takes place in A. Tracheid with associated xylem parenchyma B. Xylem parenchyma C. Walls of tracheary elements D. Lumen of tracheary elements www. wisedane. com
ANSWER (B) EXPLANATION: Ø Though trachieds have transverse walls intact, the septal perforations are so large; they provide continuous system and do not afford much resistance for the smooth flow of water in them. Ø The xylem parenchyma among the dead tracheid and tracheary elements provides access for the lateral movement of water from vertical xylem elements towards cortical cells contributing to ascent of sap. Ø The analysis of liquid that is exuded through the xylem elements, further show that the liquid is not just pure water, but is contains many inorganic and organic components absorbed by the root system. www. wisedane. com
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