During meiosis, a hexaploid hybrid spontaneously eliminates one set of chromosomes (eliminates 1n). What is the most likely result of this deletion?

Question

A.  The hybrid will no longer be able to reproduce.
B.  The hybrid will be able to reproduce with one of the parental species.
C.  The hybrid will no longer be polyploid.
D.  The hybrid will be able to reproduce only by self-fertilization.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?
 
Gather Content
· What do you already know about polyploidy?
 
Consider Possibilities
· Consider the different answer options. Which can you rule out?
  Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
 
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

A.  The hybrid will no longer be able to reproduce.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses polyploidy.
· What type of thinking is required?
        o This question is asking you to take what you already know and apply it to this unfamiliar situation.
· What key words does the question contain and what do they mean?
        o Meiosis is the process of sorting and dividing chromosomes for gamete formation.
        o A hexaploid is an organism that has 6 sets of chromosomes; it is 6n.
 
Gather Content
· What do you already know about polyploidy?
        o Polyploidy has occurred numerous times in the evolution of the flowering plants.
        o Allopolyploids arise by hybridization of two lineages followed by genome duplication.
        o Unless the hybrid genome is doubled, a hybrid plant will be sterile because it will lack homologous chromosomes that need to pair during metaphase I of meiosis.
        o Because meiosis requires an even number of chromosome sets, only species with ploidy levels that are multiples of two can reproduce sexually.
 
Consider Possibilities
· Consider the different answer options. Which can you rule out?
        o If a 6n species loses 1n, it becomes 5n.
        o Would a 5n hybrid no longer be polyploid? No, it would still be polyploid as 5n > 2n.
        o Would a 5n hybrid be able to reproduce with one of the parental species? No. With 5 sets of chromosomes, during meiosis they will be unable to assort properly and the gametes will be aneuploid.
        o Would a 5n hybrid be able to reproduce only by self-fertilization? No. Even with itself, the aneuploid gametes would likely still be missing chromosomes, even in combination.
  Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Will the 5n hybrid no longer be able to reproduce at all? Yes, most likely. With 5 sets of chromosomes, during meiosis they will be unable to assort properly and the gametes will be aneuploid.
 
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?         o This question asked what would occur if a hexaploid species became 5n instead.
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that a 5n species cannot make viable gametes, because there is an odd number of chromosomes?