scientific biological reasons (dna & chromosome)

Biological Reasons: 1 Dr. Sajid Ali Talpur

Chapter 6

DNA and Chromosome (Don’t just pass life, just pass in life…!)


Q 1: Why DNA is considered as King, RNA as

minister and protein as labour?

Ans. Because DNA by being lodged in nucleus

sends commands which are carried by RNA and

protein (or enzymes) finally function in the

metabolic reactions.

Q 2: Why the term chromosome is misnomer?

Ans. Because they are not colored bodies.

Q 3: If the term chromosome is misnomer then why

it is named so?

Ans. it is because when Germen Embryologist

Fleming discovered then they stained much darker

than the rest of the organelles.

Q 4: Can chromosomes be seen in normal, non-

dividing cells?

Ans. No, because in a resting cell they are present in

the form of a network and appear only during the

cell division.

Q 5: The sex of baby is determined by father or

mother?

Ans. It is determined by Father’s chromosome.

Because mother’s both the chromosomes are XX

are similar but the father’s XY chromosomes are

dissimilar and if the X is contributed the baby will

be girl and if Y is contributed the baby will be boy.


Q 6: Can males have like and females unlike

chromosomes?

Ans. Yes, but in few animal species like moths,

birds and some fishes where males have ZZ and

females have ZW chromosomes.

Q 7: How the histones and DNA remain tightly

bound together?

Ans. DNA are negatively charged and histones are

positively charged so they remain tightly bound

together.

Q 8: Which of the sperm and egg contributes more

to the formation of zygote?

Ans. Both of the gametes contribute equally

because each of them contains equal no. of 23

chromosomes in humans.

Q 9: Why R-type bacteria are non virulent whereas

the S-type virulent?

Ans. S-type bacteria are virulent because they are

covered by capsule which prevents them from being

digested by WBC.

Q10: Why replication is considered as semi

conservative?

Ans. Since each DNA molecule is consist of two

strands and after replication new DNA molecule

contains one old and one new strand. Hence the

duplex is not conserved rather, each strand becomes

the part of the other duplex.


Q11: Why the urine of Alkaptonuria patient turns

black on exposure to the air?

Ans. because such a urine contains homogentisic

acid which is oxidized when exposed to air and

turns black.

Q12: Why proteins are synthesized in cytoplasm but

not in the nucleus?

Ans. because the protein factories called ribosomes

are present in cytoplasm also the amino acids

required for protein synthesis are available in

cytoplasm but not in the nucleus.

Q13: There are only 20 basic different amino acids

and millions of the proteins. Explain it.

Ans. However, there are only 20 basic proteins but

their sequence is different in each protein. It is as

there are 26 basic alphabetic letters but millions of

the words.


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