Question 251 of 408
Transport In Plants
Xylem translocates:
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Class XI & XII · Biology practice
Botany PYQs
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408 questions in this collection · Page 26 of 41
Question 252 of 408
Transport In Plants
Grass leaves curl inwards during very dry weather.
Select the most appropriate reason from the
following:
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Question 253 of 408
Transport In Plants
What is the direction of movement of sugars in
phloem?
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Question 254 of 408
Mineral Nutrition
Thiobacillus is a group of bacteria helpful in carrying out:
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Question 255 of 408
Respiration In Plants
Respiratiory Quotient (RQ) value of tripalmitin is:
AI-generated explanation. Check against your textbook.
Explanation:
RQ = CO2 evolved / O2 consumed during respiration. For fats (like tripalmitin, a triglyceride), RQ is about 0.7, as fats yield more energy with less CO2 per O2 consumed. Therefore, the RQ value of tripalmitin is 0.7 (option 3).
🧠 Did You Know?
Carbohydrates have RQ ≈ 1.0, proteins ≈ 0.8, and fats ≈ 0.7. Lipids produce less CO2 per O2 used compared with carbohydrates.
💡 NCERT Memory Line:
RQ of carbohydrates is about 1.0; fats give about 0.7; proteins around 0.8—these values help identify fuel utilization in cellular respiration.
Question 256 of 408
Plant Growth And Development
It takes very long time for pineapple plants to
produce flowers. Which combination of hormones
can be applied to artificially induce flowering in
pineapple plants throughout the year to increase
yield?
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Question 257 of 408
Plant Growth And Development
What is the site of perception of photoperiod
necessary for induction of flowering in plants:
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Question 258 of 408
Sexual Reproduction In Flowering Plants
Which one of the following statements regarding
post-fertilization development in flowering plants is incorrect?
AI-generated explanation. Check against your textbook.
Explanation:
The incorrect statement is 1. In NCERT, the embryo sac (female gametophyte) develops inside the ovule after megasporogenesis; the ovule itself does not become the embryo sac. The ovary, after fertilization, develops into fruit; the zygote develops into embryo; and the central cell with polar nuclei fertilizes to form endosperm. Thus, 2, 3, and 4 are true statements.
🧠 Did You Know?
The embryo sac forms within the ovule and later participates in double fertilization with the sperm, leading to embryo and endosperm formation.
💡 NCERT Memory Line:
The ovary develops into fruit; the ovule contains the embryo sac; the zygote forms the embryo; the central cell forms endosperm.
Question 259 of 408
Sexual Reproduction In Flowering Plants
Is some plants, the female gamete develops into
embryo without fertilization. This phenomenon is
known as:
AI-generated explanation. Check against your textbook.
Explanation:
Parthenogenesis is the development of an embryo from the female gamete without fertilization. In some plants, the female gamete can develop into an embryo without a sperm cell, which is why option 1 is correct.
🧠 Did You Know?
Syngamy is the fusion of male and female gametes. Parthenocarpy refers to fruit development without fertilization. Autogamy is self-fertilization within a flower.
💡 NCERT Memory Line:
Parthenogenesis is the development of the female gamete into an embryo without fertilization.
Question 260 of 408
Principles Of Inheritance And Variation
In Antirrhinum (Snapdragon), a red flower was
crossed with a white flower and in F1 generation, pink flowers were obtained. When pink flowers were selfed, the F2 generation showed white, red and pink flowers.
Choose the incorrect statement from the following :
Choose the incorrect statement from the following :
AI-generated explanation. Check against your textbook.
Explanation:
The cross red x white in Antirrhinum shows incomplete dominance, yielding pink in F1. In F2, segregation of alleles gives 1 red : 2 pink : 1 white, confirming incomplete dominance and that the Law of Segregation does apply (gametes carry alleles, and they segregate during formation). Therefore statement 1 is incorrect. Statements 2, 3, and 4 are consistent with NCERT: ratio 1/4 red, 1/2 pink, 1/4 white; pink in F1 results from incomplete dominance; and the experiment does not follow complete dominance.
🧠 Did You Know?
In incomplete dominance, heterozygotes show a third phenotype (pink) distinct from either homozygote (red or white).
💡 NCERT Memory Line:
Antirrhinum shows incomplete dominance; F2 phenotype ratio is 1:2:1 (red:pink:white) due to segregation of alleles.
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