Which of the following statements are correct about
Klinefelter's Syndrome?
A. This disorder was first described by Langdon Down (1866).
B. Such an individual has overall masculine development. However, the feminine development is also expressed.
C. The affected individual is short stature.
D. Physical, psychomotor and mental development is retarded.
E. Such individuals are sterile.
Choose the correct answer from the options given below:
AI-generated explanation. Check against your textbook.
Explanation:
Explanation per NCERT: A is incorrect (Klinefelter's described by Klinefelter, not Langdon Down). B is considered correct: individuals are male but may show some feminine features due to hypogonadism. C is incorrect: affected individuals are typically tall, not short. D is not a general NCERT statement; mental development may be affected mildly but is not described as broadly retarded. E is correct: such individuals are sterile due to impaired spermatogenesis.
🧠 Did You Know?
Klinefelter's syndrome results from a 47,XXY karyotype in males, leading to hypogonadism and characteristic features.
💡 NCERT Memory Line:
Klinefelter's syndrome: male with extra X chromosome; often tall, with underdeveloped secondary sexual traits; sterility is common.
Main steps in the formation of Recombinant DNA are given below. Arrange these steps in a correct sequence.
A. Insertion of recombinant DNA into the host cell.
B. Cutting of DNA at specific location by restriction enzyme.
C. Isolation of desired DNA fragment.
D.Amplification of gene of interest using PCR
Choose the correct answer from the option given below:
AI-generated explanation. Check against your textbook.
Explanation:
The correct sequence is B, C, D, A. First, B: restriction enzymes cut DNA at specific locations. Next, C: the desired DNA fragment is isolated from the rest. Then, D: the gene is amplified using PCR to obtain enough copies. Finally, A: the recombinant DNA is inserted into the host cell for expression. This order reflects the typical steps described in NCERT for recombinant DNA technology, from cutting to isolating, amplifying, and inserting into a host.
🧠 Did You Know?
PCR stands for polymerase chain reaction and helps make many copies of the gene of interest before insertion.
💡 NCERT Memory Line:
Restriction enzymes cut DNA; isolate the fragment; amplify the gene; insert into host cells.
Given below are two statements: Statement I: Gause's "Competitive Exclusive Principle" states that two closely related species competing for the same related species competing for the same resources cannot co-exist indefinitely and competitively inferior one will be eliminated eventually. Statement II: In general, carnivores are more adversely affected by competition than herbivores.
In the light of the above statements, choose the correct answer from the options given below:
AI-generated explanation. Check against your textbook.
Explanation:
Statement I is correct. Gause’s Competitive Exclusion Principle says two species competing for the same limited resources cannot coexist indefinitely; one will be excluded due to competition. This is the idea of competitive exclusion. Statement II is false as per NCERT: in general, competition affects herbivores more because plant resources are often patchy and limited, leading to stronger interspecific competition among herbivores. Carnivores typically have more dispersed prey and may face less direct competition for a single resource, so they are not described as being more adversely affected by competition in the NCERT context. Therefore, only Statement I is true, making option 4 correct.
🧠 Did You Know?
Gause conducted experiments with Paramecium species to illustrate competitive exclusion, showing that two species with identical needs could not stably coexist.
💡 NCERT Memory Line:
Competitive Exclusion Principle states two species competing for the same resource cannot coexist indefinitely.