ADA sample bio!

[yakuza]

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Aight so I just took the bio section of the ADA test and missed 2..both being genetics and I have no idea how to think them out.


27.

​

Assuming no linkage, how many different

kinds of gametes can be produced by an

organism with the genotype AaBbcc?​

A. 32

B. 16
C. 8
D. 6
E. 4​

28. ​

Which of the following statements

concerning alleles is true for diploid

organisms?
1. At most only two alleles occur at a
given locus in an organisms
genome.
2. Alleles occupy an identical locus in
homologous chromosomes.
3. Alleles of a given gene usually
occur on non-homologous
chromosomes.
4. A single chromosome usually
carries two alleles of each gene.​

A. 4

B. 1 and 2
C. 3
D. 1, 2 and 4​

E. 3 and 4​

Help please​

 

[yakuza]

by the way its not as easy as people claim, theres a couple of trickyass questions

 

[dentalknight]

what are the answers to these questions? i may have an idea of how to do the first one but i just wanna make sure what the answer is first

 

[DDSguyLA]

i think first one is 32 and second one is 4 "A"

 

[PooyaH]

i think first one is 32 and second one is 4 "A"

First one is E.

 

[AndyK]

#1 is E)4

Organism is AaBbcc... so gametes can be ABc, aBc, Abc, abc... four kinds of gametes. Think about meiosis: you start with a diploid and end up with a haploid. The question says there is no linkage, therefore the alleles segregate indepedently. After that, it's just a probability question 🙂

#2) B. Point 3 is false because alleles of a gene are only on homologous chromosomes. For instance, maternal chromosome 21 has an "A" allele and paternal chromosome 21 has "a" allele. Point 4 is false because there is only one allele of a gene per chromosome; there are two alleles per homolog

 

[yakuza]

The answers are in red, can yall explain?

 

[yakuza]

#1 is E)4

Organism is AaBbcc... so gametes can be ABc, aBc, Abc, abc... four kinds of gametes

#2) B. Point 3 is false because alleles of a gene are only on homologous chromosomes. For instance, maternal chromosome 21 has an "A" allele and paternal chromosome 21 has "a" allele. Point 4 is false because there is only one allele of a gene per chromosome; there are two alleles per homolog

Eh..genetics is my weakness. So this organism AaBbcc..what is it reproducing with? Bc it asks what kind of gametes can it produce

 

[ongmeister]

Aight so I just took the bio section of the ADA test and missed 2..both being genetics and I have no idea how to think them out.


27.

Assuming no linkage, how many different

kinds of gametes can be produced by an

organism with the genotype AaBbcc?​

A. 32

B. 16
C. 8
D. 6
E. 4​

28. ​

Which of the following statements

concerning alleles is true for diploid

organisms?
1. At most only two alleles occur at a
given locus in an organisms
genome.
2. Alleles occupy an identical locus in
homologous chromosomes.
3. Alleles of a given gene usually
occur on non-homologous
chromosomes.
4. A single chromosome usually
carries two alleles of each gene.​

A. 4

B. 1 and 2
C. 3
D. 1, 2 and 4​

E. 3 and 4​

Help please​

For the first one.

You do this one by knowing that herterozygous is 2 and recessive is 1. So it becomes 2x2x1 = 4

 

[yakuza]

For the first one.

You do this one by knowing that herterozygous is 2 and recessive is 1. So it becomes 2x2x1 = 4

What if its mating with AABBCC or aabbcc?

 

[AndyK]

Gametes are the haploid cells/the germ line/sperm and eggs. You're thinking of the zygote or offspring. Male makes haploid sperm gametes, female makes haploid egg gametes... when they meet you have a diploid zygote. The question only asks about the gametes. Like I said in my edited post, you should review meiosis with respect to allele segregation.

 

[yakuza]

I see. So AaBBcc would equal 2x1x1=2?

 

[ongmeister]

What if its mating with AABBCC or aabbcc?

Then it would be just one. SInce homozygous means 1. So 1x1x1

Plus you should know that its mating a homozygous dominant and recessive only one genotype will form. AaBbCc and nothing else.

 

[ongmeister]

I see. So AaBBcc would equal 2x1x1=2?

Yup! good job!

 

[AndyK]

I just saw that the second one was 1,2,4 not 1,2. Can someone explain why this is? I always thought it was one allele per chromosome.

 

[yakuza]

I just saw that the second one was 1,2,4 not 1,2. Can someone explain why this is? I always thought it was one allele per chromosome.

I'm pretty sure now that each chromatid holds an allele. So 1 chromatid may have p and the other pay also have p

 

[AndyK]

I'm pretty sure now that each chromatid holds an allele. So 1 chromatid may have p and the other pay also have p

Chromatids are not to be confused with chromosomes. "Chromatid" is a term for when after the genome has been replicated during S phase in preparation for mitosis or meiosis. The sister chromatids that make up the X-shaped chromosome are genetically identical. After mitosis/meiosis, you only have one chromatid or, more properly, one chromosome.

I really think that the answer is erroneous... someone please prove me wrong 🙂

 

[dentalgirlyay]

27.

Assuming no linkage, how many different

kinds of gametes can be produced by an

organism with the genotype AaBbcc?​

A. 32

B. 16
C. 8
D. 6
E. 4

okay for #27 I think this is how they got the answer 4. Since there are two heterozygous gene pairs invovled in the cross which means that n=2 and once n is determined we use the formula 2^n which is the # of different gametes that can be formed. so then it will be 2^(2) = 4 I hope i am correct! lol​

 

[acupofchai]

ok for number 1:

AaBbcc (2n) to produce a gamete with only 1 allele 👎 each

Because of cc, the gamete can ONLY have c, so you can disregard looking at c.

Now, look at AaBb. There are 4 combinations (plus a small c):

ABc
Abc
aBc
abc

Answer is E.

 

[dentalknight]

Chromatids are not to be confused with chromosomes. "Chromatid" is a term for when after the genome has been replicated during S phase in preparation for mitosis or meiosis. The sister chromatids that make up the X-shaped chromosome are genetically identical. After mitosis/meiosis, you only have one chromatid or, more properly, one chromosome.

I really think that the answer is erroneous... someone please prove me wrong 🙂

actually i think that a chromosome has two chromatids. When it has just one chromatid by itself, then a chromosome is the same thing as a chromatid. when a chromsome has two sister chromatids, each chromatid contains one allele, making a total of 2 alleles on one chromosome. thats why #4 is correct on the second question.

 

[pauly11235]

use the formula n(squared) where n is equal to the total number of heterozygous not homozygous. there are 2 in that problem Aa and Bb so 2 Squared is 4. Choice E.