Molecular Basis Of Inheritance(12th Grade > Biology ) Questions and Answers
Explanation:-
Answer: Option A. -> X-ray diffraction:
A
Rosalind Franklin, a young biophysicist, was working on the structure of DNA around the same time as Watson and Crick. While they initially came up with a triple helical structure, she already had a strong clue that DNA is a double helix, through the images that she had developed through X-ray diffraction. Unfortunately, she wasn’t alive to share the Nobel Prize with them in the year 1962.
Explanation:-
Answer: Option B. -> False:
B
DNA is a long molecule compactly arranged in the nucleus of the cell. When stretched out, the length of the DNA molecule from a single cell measures longer than the average height of a human being.
Explanation:-
Answer: Option A. -> Information is free for use for the scientific community:
A
It was unanimously accepted that if the information obtained by HGP was not kept open and easily accessible to all, the purpose of helping the scientific community to grow would fail. The easiest way was to keep the information available in an online database for everyone to access.
Explanation:-
Answer: Option D. -> Mutations can never be acquired from the environment.:
D
Mutations can either be inherited or may occur due to environmental factors. Ultraviolet radiation and certain chemicals are typical examples of environmental factors that can cause mutations.
Explanation:-
Answer: Option B. -> Promoter:
B
An operon is typically comprised of three regions - promoter, operator and the structural genes. Additionally most operons would also have a regulatory gene. The promoter is recognised by RNA polymerase,which then binds to it and initiates transcription.
Explanation:-
Answer: Option B. -> Nucleus, ribosome:
B
DNA gets transcribed into mRNA within the nucleus. The mRNA gets processed, and moves out through the nuclear pores into the cytoplasm to get attached to the ribosomes for protein synthesis. In eukaryotes, the endoplasmic reticulum lies right outside the nucleus, and its membrane is in fact, continuous with the outer nuclear membrane. The rough endoplasmic reticulum is studded with ribosomes. There are also free ribosomes in the cytoplasm of a cell. Translation of mRNA to protein can happen in both attached and free ribosomes.
Question 9. Match the following enzymes of DNA replication with their respective functions:
p. DNA polymerasei. Helps unzip the DNA double helixq. DNA ligaseii. Seals nicks between Okazaki fragmentsr. DNA helicaseiii. Lays RNA primers to which polymerase can add nucleotidess. Primaseiv. Adds nucleotides to the free 3′ end of RNA primers
p. DNA polymerasei. Helps unzip the DNA double helixq. DNA ligaseii. Seals nicks between Okazaki fragmentsr. DNA helicaseiii. Lays RNA primers to which polymerase can add nucleotidess. Primaseiv. Adds nucleotides to the free 3′ end of RNA primers
Explanation:-
Answer: Option C. -> p - iv, q - ii, r - i, s - iii:
C
Among the major enzymes involved in DNA replication, DNA polymerase primarily performs the task of adding nucleotides to the free 3’ end of the RNA primers. DNA ligase seals up any nicks formed in the newly synthesised DNA strands, such as those between Okazaki fragments in the lagging strand and between the fragment that replaced RNA primer and the rest of the nucleotides added by DNA polymerase. However, ligase does not add nucleotides (which is done only by polymerase) to fill in gaps. DNA helicase is involved in unzipping the DNA double helix, which it achieves by breaking up of the hydrogen bonds between the nucleotides of each base pair. Primase, specifically the RNA primase enzyme, lays down the short RNA primers at the beginning of replication so that, DNA polymerase can start adding nucleotides to the free 3’ end of the primers to form the new strands.
Explanation:-
Answer: Option B. -> Heat-killed R strain - Virulent:
B
Griffith considered two different strains of the bacterium Streptococcus pneumoniae - S strain and R strain. The former is pathogenic/virulent and can cause the disease, while the latter is non-pathogenic/non-virulent and cannot cause the disease. Heat-killed S strain bacteria however, lose their virulence and become non-pathogenic. R strain bacteria in general, don’t need to be heat-killed as they are already non-pathogenic.