Home » Ask & Discuss » Biology (for Medical Entrance) » Botany « Back to Discussion

Botany

New kid on the Block

Joined:	6 Mar 2008
Post:	24

20 Jan 2009 21:42:21 IST

0 People liked this

197

PLease.... solve

None

1) Trihybrid ratio is

a) 27:9:9:9:3:3:3:1

b) 27:9:9:6:6:3:3:1

c) 1:6:15:20:15:6:1

d) 36:6:6:6:3:3:3:1

2) Ratio between completely homozygous dominant and homozygous recessive individuals of dihybrid cross is

a) 1:1

b) 2:2

c) 6:10

d) 10:6

3) A dihybrid cross is made between YYrr and yyRR. In F2 generation the ratio of parental to recombinant phenotype is

a) 75%

b) 50%

c) 25%

d) 12.5%

4) A Yellow round seeded Pea plant is crossed with green wrinkled seeded Pea plant. Four phenotypes appeared in the progeny in the ratio of 1:1:1:1.The genotype of the two ratio are

a) YyRr

b) YYRR

c) YyRR

d) yyRr

PLEASE ANSWER WITH SOLUTION.

THANKS IN ADVANCE.

Share this article on:

Comments (3)

Sahithya

Blazing goIITian

Joined: 3 Sep 2008

Posts: 485

21 Jan 2009 13:07:26 IST

Like 0 people liked this

1 a 27:9:9:9:3:3:3:1

victor

New kid on the Block

Joined: 20 Oct 2008

Posts: 21

22 Jan 2009 11:28:07 IST

Like 0 people liked this

for 1st.. a) 27:9:9:9:3:3:3:1 , for 2nd) 1:1 ( only one AABB and aabb), 3rd ) F1 = YyRr , parental phenotypes in F2 = Y_rr + yyR_ where in _ , you can fill either dominant or recessive allele... it will be 6/16 in total i.e there will be 6 parental phenotypes.. recombinant will be 10 out of 16..so, ratio comes out to be near 60% for 4th) answer is YyRr .. then only can the ratio 1:1:1:1 obtained..

Honey Arora

New kid on the Block

Joined: 17 Jul 2008

Posts: 6

22 Jan 2009 22:48:00 IST

Like 1 people liked this

Q1) explaination

in a dihybrid cross we get ratio 9:3:3:1 by multiplying (3:1)(3:1) coz independent charecters segregate independent of each other(law of independent assortment) likewise u cn get the reqd ratio by multiplying (3:1)(3:1)(3:1) => (9:3:3:1)(3:1) =>27:9:9:9:3:3:3:1

Quick Reply

Reply

	Some HTML allowed.
	Keep your comments above the belt or risk having them deleted.
	Signup for a avatar to have your pictures show up by your comment
	If Members see a thread that violates the Posting Rules, bring it to the attention of the Moderator Team