101. The force that keeps the water column in xylem continuous is:
Answer: B. cohesion and adhesion
Biology Class 11 Unit 9: Diversity in Plant Functions MCQs
278 multiple choice questions with the correct answer for each. Tap an option to check yourself, or switch on "Show all answers". This is page 3 of 6.
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102. The bulk flow of water to the top of the plant is driven by:
Answer: C. solar energy through evaporation
103. Stomata are generally:
Answer: B. open in day and closed (incompletely) at night
104. The opening and closing of stomata depends on the:
Answer: B. turgidity of guard cells
105. Stomata open when guard cells are:
Answer: B. turgid
106. Guard cells are the only photosynthesizing cells of the:
Answer: B. leaf epidermis
107. According to the starch sugar interconversion theory, in the morning sugar in guard cells:
Answer: B. increases, lowering water potential so water enters
108. At night in guard cells glucose is converted to:
Answer: B. starch
109. In K plus ion influx theory, low CO2 level favours the:
Answer: B. influx of K plus ions into guard cells
110. K plus ions in guard cells combine with malate ions to form:
Answer: B. potassium malate
111. The movement of K plus into guard cells occurs by:
Answer: C. active transport
112. Blue light causes ionization of:
Answer: B. malic acid
113. The movement of organic solutes through phloem is called:
Answer: C. translocation
114. Translocation always occurs from a:
Answer: B. source to sink
115. A leaf is purely a:
Answer: B. source
116. A fruit is particularly a:
Answer: B. sink
117. Roots and stems can act as:
Answer: C. both source and sink
118. Phloem sap contains how much dry matter?
Answer: B. 10 to 25 percent
119. Of the dry matter in phloem sap, about 90 percent is:
Answer: C. sucrose
120. The theory explaining translocation is the:
Answer: B. pressure flow (mass flow) theory
121. According to pressure flow, sugar is loaded in sieve tubes at the source by:
Answer: C. active transport requiring ATP, with water entering by osmosis
122. At the sink, sugar is unloaded and water:
Answer: B. leaves the sieve tube by osmosis
123. Homeostasis is the ability to:
Answer: B. maintain a steady state in a changing environment
124. Maintenance of water and solute level in the body is called:
Answer: B. osmotic adjustment (osmoregulation)
125. A hypotonic medium has water potential:
Answer: B. higher than cell sap
126. In a hypotonic medium the plant cell becomes:
Answer: C. turgid
127. In a hypertonic medium water moves:
Answer: B. out of the cell (exosmosis)
128. In an isotonic medium:
Answer: C. there is no net movement of water
129. Plants that grow where abundant water is available are:
Answer: C. hydrophytes
130. Hydrophytes are exposed to which kind of osmotic condition?
Answer: C. Hypotonic
131. Hydrophytes have stomata:
Answer: C. on upper epidermis, open day and night
132. Hydrophytes have a:
Answer: B. very thin cuticle or none
133. Wheat, rice and maize are examples of:
Answer: C. mesophytes
134. Mesophytes face nearly:
Answer: C. isotonic condition
135. Mesophytes have stomata mainly on the:
Answer: B. lower epidermis, open in day and closed at night
136. Desert plants like cactus and Opuntia are:
Answer: C. xerophytes
137. Xerophytes face which osmotic condition?
Answer: C. Severely hypertonic
138. Xerophytes show:
Answer: C. very low rate of transpiration
139. Xerophytes have stomata that are:
Answer: B. sunken in depressions, closed in day and open at night
140. Succulent plants store:
Answer: C. a very high amount of water
141. Plants in saline soils are:
Answer: D. halophytes
142. Saline soils create:
Answer: B. physiological drought
143. Halophytes cope with salinity by accumulating Na plus and Cl minus in:
Answer: C. vacuoles of leaf cells
144. Some halophytes make osmotic adjustment by accumulating:
Answer: B. compatible solutes like glycine betaine and sorbitol
145. Low temperature affects the cell membrane by making lipids:
Answer: B. less fluid (crystallize)
146. To avoid crystallization of membrane lipids at low temperature, plants increase:
Answer: B. unsaturated fatty acids
147. Heat shock proteins help in:
Answer: C. preventing denaturation of enzymes at high temperature
148. In very hot areas plants develop a:
Answer: B. shiny cuticle that reflects light
149. At temperatures above 45 degrees plants:
Answer: B. close their stomata to prevent water loss
150. The pressure on cell walls due to water in a turgid cell is:
Answer: B. turgor pressure
About Biology Class 11 Unit 9 MCQs (Federal Board)
These 278 Biology MCQs cover Class 11 Unit 9: Diversity in Plant Functions of the Federal Board (FBISE) HSSC-I (1st Year / Class 11) syllabus. They are SLO-based MCQs as per the new pattern for FBISE exams. Each question has four options and the correct answer is shown, so you can practise for the annual examination and find the topics you still need to revise. The questions are split over 6 pages of 50. Use the Print button to save this chapter as a PDF.