Question

A species of plant will produce either green or brown seeds. The table below shows the results of several experiments using cross between plants that produce each color seed.

Based on the data in the table, which pattern of inheritance controls seed color in this plant species?

Answer 1

@Abhisar @ganeshie8 @bloopman

Answer 2

Either:

Codominance
Complete Dominance
Incomplete dominance
Multiple alleles

Answer 3

@bloopman ?

Answer 4

do you know the definitions of these terms? if you do, you shouldn't have a problem with this problem i don't think

Answer 5

I don't know Codominance

Answer 6

what do you think the answer is atm

Answer 7

I think its D, but I could be wrong.

Answer 8

Sorry, B. Because there is a dominant trait.

Answer 9

@bloopman ?

Answer 10

but is it completely dominant?

Answer 11

No, not entirely

Answer 12

so it's not D

Answer 13

But are you sure it would be incomplete dominance?

Answer 14

Yeah, it's not D for sure

Answer 15

@bloopman ?

Answer 16

what do you think the definition of incomplete dominance is?

Answer 17

Something that is not entirely dominant but is more common

Answer 18

notice how in brown x green one trial concluded that there were 0 brown seeds

Answer 19

Okay

Answer 20

So brown isn't dominant, its recessive?

Answer 21

@bloopman ?

Answer 22

i've essentially given you the answer :P

Answer 23

I don't see how... I have been saying C is the answer, but you keep on telling me stuff that further confuses me...

Answer 24

@Abhisar ?

Answer 25

i am not getting the table, what is plant 1, plant 2 & plant 3

Answer 26

@Abhisar

Answer 27

Or just go to http://tinypic.com/r/xnx1jm/8

Answer 28

I'll go with complete dominance

Answer 29

Are you sure, what makes you say that?

Answer 30

@themathwiz Give me one second I am working out the chi squared for the expected vs. obeserved.

Answer 31

okay @mrdoldum

Answer 32

I Think its so because the phenotypic ratio i got 3:1 in Green X Green

Answer 33

But it would be better if u cross check it with @mrdoldum

Answer 34

Okay thank you @Abhisar

Answer 35

I will

Answer 36

@mrdoldum , are you still here?

Answer 37

@themathwiz @Abhisar So, part of the difficulty in the question is the ambiguousness in the cross. We know that the first set is brown x brown. Was the same brown plant crossed with plants 1, 2, and 3? But let's just move testing a complete dom/res relationship with green (C) dom. and brown (c) res.

For the brown x brown; we would assume genotypes are cc and cc resulting in 100% cc offspring and that is what we see.

Answer 38

For green x brown, the genotypes could be CC x cc or Cc x cc. CC x cc would result in 100% green and Cc x cc would result in a 50/50 spit. We see something that strongly supports because we have 119/239 (49.79%) and 111/225 (49.333%). Looks like we did have one CC x cc cross and two Cc x cc crosses.

Now, finally for green x green. We have the following options: CC x CC, Cc x CC, CC x Cc, and finally Cc x Cc. Only the last options, Cc x Cc would have any brown seed offspring and it should have the typical 3:1 split. What do we see. 0/226 brown, 0/206 brown, and 57/228 brown. 57/228 is exactly 25% meaning that 75% are green.

So, it does look simple complete dominant/recessive. and indeed the chi squared of merging total offspring in each cross strongly supports this conclusion as well.

Answer 39

Okay, thank you so much @mrdoldum