Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Mendel’s law of Independent assortment does not hold good for the genes that are located closely on the same chromosome. Reason (R): Closely located genes assort independently.
In the light of the above statements, choose the correct answer from the options given below:
If a geneticist uses the blind approach for sequencing the whole genome of an organism, followed by assignment of function to different segments, the methodology adopted by him is called as:
The anatomy of springwood shows some peculiar features. Identify the correct set of statements about springwood.
A. It is also called as the earlywood
B. In spring season cambium produces xylem elements with narrow vessels
C. It is lighter in colour
D. The springwood along with autumnwood shows alternate concentric rings forming annual rings
E. It has lower density
Choose the correct answer from the options given below :
AI-generated explanation. Check against your textbook.
Explanation:
Springwood (earlywood) is formed in the spring and consists of wider xylem vessels and thinner walls, making it lighter in color and with lower density. It forms part of the annual ring with Autumnwood (latewood). Thus A is true, C true, D true, and E true. Statement B is false because springwood has wide, not narrow, vessels. The correct set is A, C, D and E.
🧠 Did You Know?
Annual rings are formed by the alternating growth in spring (earlywood) and late summer/fall (latewood), creating distinct light and dark zones in the stem.
💡 NCERT Memory Line:
Earlywood is lighter, has wide vessels and lower density; latewood is darker and denser, forming the characteristic yearly rings.
In the following palindromic base sequences of DNA, which one can be cut easily by particular restriction enzyme?
AI-generated explanation. Check against your textbook.
Explanation:
Only option 2 shows a perfect palindromic sequence: 5' GAATTC 3' matches 3' CTTAAG 5' as its reverse complement. This is the recognition site for the restriction enzyme EcoRI, which cuts between G and A to yield sticky ends. Other options are not true palindromes (the sequences do not read the same in the opposite direction on the complementary strand), so they are not typical EcoRI sites. NCERT emphasizes that restriction enzymes recognize palindromic sequences and cut within them to produce sticky or blunt ends.
🧠 Did You Know?
Palindromic DNA sequences read the same forward on one strand and backward on the complementary strand, enabling precise enzymatic cuts.
💡 NCERT Memory Line:
Palindromic sequences are read the same in the 5'→3' direction on both strands and are common recognition sites for restriction enzymes.
Transposons can be used during which one of the following ?
AI-generated explanation. Check against your textbook.
Explanation:
Transposons are mobile genetic elements that can insert into genes and affect their expression. In NCERT, they are discussed as tools to study gene function, including gene silencing. When transposons disrupt or regulate genes, they can reduce or block expression, helping scientists understand gene function—i.e., gene silencing.
🧠 Did You Know?
Transposons can act as mutagens and help map genes by inserting into them, revealing functions by observation of loss or change in activity.
💡 NCERT Memory Line:
Transposons are used as tools to study gene function, including gene silencing, not for basic PCR, autoradiography, or sequencing.
