The blob operon produces enzymes that convert compound A into compound B. The operon is controlled by regulatory gene S. Normally, the enzymes encoded by the operon are synthesized only in the absence of compound B. If gene S is mutated, the enzymes are synthesized in the both the presence AND absence of compound B. Gene S must encode a(n):
a. inducer.
Answer:
Option-D
Explanation:
In the given question the genotype of parental allele is- AbaB X AbaB. The alleles formed will be- AB, Ab,aB, ab in which the crossover allele will be AB and ab.
1. Unlinked genes
Now of these alleles are unlinked then the alleles will assort independently of each other therefore performing the punnett square we will get dihybrid ratio as 9:3:3:1 in which
1. A_B_ are 9
2. aaB_ are 3
3. A_bb are-3
4. aabb- 1
Since the crossover allele are AB and ab therefore A_B_ are 9 and aabb- 1 represent recombinant genotype.
2. Linked genes
When the genes will be linked then chances of crossing over will be reduced as a result of which only two type of allele will be formed which are- Ab and aB and the recombinant frequency will become less.
Crossing these allele will form Aabb
, AaBb
, AaBb and aaBB genotypes.
The recombinant ratio will decrease as A_B_ is 2 and aabb is not present.
Thus, option-4 which states that the unlinked ration is 9:3:3:1 and linked ratio is <9: >3: >3: <1 is correct.
Trace fossils include footprints, trails, burrows, feeding marks, and resting marks. Trace fossils provide information about the organism that is not revealed by body fossils. Trace fossils are formed when an organism makes a mark in mud or sand.
