141. Which among these is the correct combination of aquatic mammals?
(1) Seals, Dolphins, Sharks
(2) Dolphins, Seals, Trygon
(3) Whales, Dolphins, Seals
(4) Trygon, Whales, Seals
Answer (3)
Sol. Sharks and Trygon (sting ray) are the members of chondrichthyes (cartilaginous fish) while whale, Dolphin and Seals are aquatic mammals belong to class mammalia.
142. With reference to factors affecting the rate of photosynthesis, which of the following statements is not correct?
(1) Light saturation for CO 2 fixation occurs at 10% of full sunlight
(2) Increasing atmospheric CO 2 concentration upto 0.05% can enhance CO 2 fixation rate
(3) C 3 plants responds to higher temperatures with enhanced photosynthesis while C 4 plants have much lower temperature optimum
(4) Tomato is a greenhouse crop which can be grown in CO 2 – enriched atmosphere for higher yield
Answer (3)
Sol. In C 3 plants photosynthesis is decreased at higher temperature due to increased photorespiration.
C4 plants have higher temperature optimum because of the presence of pyruvate phosphate dikinase enzyme, which is sensitive to low temperature.
143. Asymptote in a logistic growth curve is obtained when
(1) The value of ‘Y’ approaches zero
(2) K = N
(3) K > N
(4) K
Answer (2)
Sol. A population growing in a habitat with limited resources shows logistic growth curve.
For logistic growth
the population reaches asymptote.
144. Out of ‘X’ pairs of ribs in humans only ‘Y’ pairs are true ribs. Select the option that correctly represents values of X and Y and provides their explanation :
Answer (1)
Sol. In human, 12 pairs of ribs are present in which 7 pairs of ribs (1 St to 7th pairs) are attached dorsally to vertebral column and ventrally to the sternum.
145. The DNA fragments separated on an agarose gel can be visualised after staining with
(1) Bromophenol blue
(2) Acetocarmine
(3) Aniline blue
(4) Ethidium bromide
Answer (4)
Sol. Ethidium bromide is used to stain the DNA fragments and will appear as orange coloured bands under UV light.
146. Functional megaspore in an angiosperm develops into
(1) Ovule
(2) Endosperm
(3) Embryo sac
(4) Embryo
Answer (3)
Sol. Megaspore is the first cell of female gametophytic generation in angiosperm. It undergoes three successive generations of free nuclear mitosis to form 8-nucleated and 7-celled embryo sac.
147. Among the following characters, which one was not considered by Mendel in his experiments on pea?
(1) Stem – Tall or Dwarf
(2) Trichomes – Glandular or non-glandular
(3) Seed – Green or Yellow
(4) Pod – Inflated or Constricted
Answer (2)
Sol. During his experiments Mendel studied seven characters.
Nature of trichomes i.e., glandular or non-glandular was not considered by Mendel.
148. Lungs are made up of air-filled sacs the alveoli. They do not collapse even after forceful expiration, because of :
(1) Residual Volume
(2) Inspiratory Reserve Volume
(3) Tidal Volume
(4) Expiratory Reserve Volume
Answer (1)
Sol. Volume of air present in lungs after forceful expiration as residual volume which prevents the collapsing of alveoli even after forceful expiration.
149. GnRH, a hypothalamic hormone, needed in reproduction, acts on
(1) Anterior Pituitary Gland and stimulates secretion of LH and oxytocin
(2) Anterior Pituitary Gland and stimulates secretion of LH and FSH
(3) Posterior Pituitary Gland and stimulates secretion of oxytocin and FSH
(4) Posterior pituitary gland and stimulates secretion of LH and relaxin
Answer (2)
Sol. Hypothalamus secretes GnRH which stimulates anterior pituitary gland for the secretion of gonadotropins (FSH and LH).
150. In Bougainvillea thorns are the modifications of
(1) Stipules
(2) Adventitious root
(3) Stem
(4) Leaf
Answer (3)
Sol. Thorns are hard, pointed straight structures for protection. These are modified stem.
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