Answer:
a) The expected phenotype of the F1 plants is 100% RrBb, red kernels.
b) The expected phenotypic classes in the F2 are: 9:3:3:1
9/16 R-B-, 3/16 rrB-, 3/16 R-bb, 1/16 rrbb
Proportions 9:6:1.
9/16 Red kernel (R-B-), 6/16 Brown kernel (rrB- + R-bb), 1/16 White kernel (rrbb)
Explanation:
<u>Available data:</u>
- brown kernel: R-bb or rrB-
1º Cross) RRBB x rrbb
F1) 100% RrBb (red kernels)
2ºCross) RrBb x RrBb
Gametes) RB RB
Rb Rb
rB rB
rb rb
Punnet Square) RB Rb rB rb
RB RRBB RRBb RrBB RrBb
Rb RRBb RRbb RrBB Rrbb
rB RrBB RrBb rrBB rrBb
rb RrBb Rrbb rrBb rrbb
F2) Phenotypic classes:
<em>9/16 R-B-</em>
<em> 3/16 rrB-</em>
<em> 3/16 R-bb</em>
<em> 1/16 rrbb</em>
Phenotypic proportions:
<em>9/16 Red kernel (R-B-)</em>
<em> 6/16 Brown kernel (rrB- + R-bb)</em>
<em> 1/16 White kernel (rrbb) </em>
Answer:
a. p53 activates transcription of WAF1.
Explanation:
<u>WAF1 transcription occurs independent of p53 during oxidative stress so p53 does not play any role in cell cycle arrest in the signaling pathway which involves WAF1 . </u>
In rest of the mentioned options, p53 plays a role directly or indirectly. During double stranded lesion in DNA in G1 phase, a sensor protein known as ATM binds the DNA lesion site. ATM is a serine/threonine kinase which phosphorylates another kinase known as chk2. After phosphorylation,<u> chk2 stabilizes transcription factor p53.</u> p53 further acts as a transcription factor for the synthesis of a protein known as p21 which inhibits G1 phase specific CDK and ultimately cell is arrested in G1 phase. The cell remains in arrested state until the DNA lesion is fully repaired. <u>Hence, p53 indirectly blocks G1 to S transition with the help of p21. </u>
As such <u>WAF1 transcription factor involving pathway</u><u> </u><u>also requires p21 protein for causing cell cycle arrest but in this pathway p21 is not synthesized with the help of p53. </u>
Plants use their stomata to take in Carbon dioxide and take out oxygen during photosynthesis. It's how they "breathe" if that makes it more understandable.
