Given below are two statements: Statement I: Cleistogamous flowers are invariably autogamous. Statement II: Cleistogamy is disadvantageous as there is no chance for cross pollination.
In the light of the above statements, choose the correct answer from the options given below :
Given below are two statements: Statement I: Mendel studied seven pairs of contrasting traits in pea plants and proposed the Laws of Inheritance. Statement II: Seven characters examined by Mendel in his experiment on pea plants were seed shape and colour, flower colour, pod shape and colour, flower position and stem height.
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: Mendel studied seven pairs of contrasting traits in pea plants and proposed the Laws of Inheritance. Statement II is also correct: the seven characters examined were seed shape and seed colour, flower colour, pod shape and pod colour, flower position, and stem (plant) height. These together constitute seven distinct traits described by NCERT. Hence, option 1 is the right choice.
🧠 Did You Know?
NCERT mentions seven contrasting characteristics studied by Mendel, which laid the foundation for the Laws of Inheritance (dominant/recessive, segregation, and independent assortment).
💡 NCERT Memory Line:
Mendel studied seven pairs of contrasting characters in peas and formulated the basic laws of inheritance.
AI-generated explanation. Check against your textbook.
Explanation:
XO type sex determination means males have one X chromosome (X0) and no second sex chromosome, while females have two X chromosomes (XX). This system is seen in grasshoppers and some other insects, where the male is the heterogametic sex with a single X. Therefore, option 3 (Grasshoppers) is correct. In Drosophila, birds, and monkeys, different systems operate: Drosophila uses an XY system, birds use a ZW system for females, and monkeys (humans) use an XY system as well. The NCERT description of XO is specifically linked to grasshoppers.
🧠 Did You Know?
In XO species, the sex chromosomes are not a pair in males; the presence of only one X determines maleness, while females have two X chromosomes.
Read the following statements and choose the set of correct statements:
A. Euchromatin is loosely packed chromatin
B. Heterochromatin is transcriptionally active
C. Histone octomer is wrapped by negatively charged DNA in nucleosome
D. Histones are rich in lysine and arginine
E. A typical nucleosome contains 400 bp of DNA helix
Choose the correct answer from the options given below:
Which one of the following statement is not true regarding gel electrophoresis technique?
AI-generated explanation. Check against your textbook.
Explanation:
Option 3 is not true. In gel electrophoresis, DNA is visualized using dyes such as ethidium bromide, which after UV illumination shows bright orange fluorescence. A chromogenic substrate does not produce blue DNA bands in this technique. The statements 1, 2, and 4 are correct: elution refers to extracting DNA strands from the gel, DNA fragments are stained with ethidium bromide, and under UV light, ethidium bromide–stained DNA bands appear orange.
🧠 Did You Know?
Ethidium bromide is a common DNA stain used in gel electrophoresis because it binds DNA and fluoresces under UV light, making the fragments visible.
💡 NCERT Memory Line:
Gel electrophoresis visualization relies on ethidium bromide staining and UV light to see orange fluorescent DNA bands; chromogenic blue bands are not part of this method.
Given below are two statements : one is labelled as
Assertion (A) and the other is labelled as Reason (R). Assertion (A): Polymerase chain reaction is used in DNA amplification. Reason (R): The ampicillin resistant gene is used as a selectable marker to check transformation
In the light of the above statements, choose the correct answer from the options given below :