Linked Genes and Crossing Over

Mendel did not observe linkage due to

• mutation
• crossing over
• synapsis
• independent assortment

crossing over in organisms is responsible for

• dominance of gene

• segregation of alles

• recombination of linked genes

• linkage between genes

Tags

NGSS.HS-LS3-2

Linked genes are

• located on different chromosomes of the same size and shape
• located on the same chromosome
• rarely inherited together

Crossing-over of parts of chromosomes:

• has no effect on genetic linkage
• usually decreases the number of genetic combinations in a population
• can increase the number of genetic combinations in a population

Tags

NGSS.HS-LS3-2

Linked genes are

• re located near each other on the same chromosome.
• violate the law of independent assortment.
• segregate together during meiosis.
• All of the above.
• None of the above

How did Morgan demonstrate crossing over?

• A fly that received only y+w+m+ and ywm chromosomes from her parents was able to transmit different combinations of alleles to her offspring.
• A fly with a gray body and red eyes (wild type) was able to produce offspring with gray bodies and white eyes.
• True breeding yellow, white, miniature flies always had yellow, white, miniature offspring.
• None of these examples demonstrate crossing over.

There is 30% recombination frequency between two genes. The distance between them in unit map is:

• 15
• 30
• 60
• 80

There are 80% parental and 20% recombinant in a cross. Its recombinant frequency is:

• 80
• 20
• 10
• 40

Tags

NGSS.HS-LS3-3

Mendel did not observe linkage due to

• There were many chromosomes to handle
• chracters he studied were located on different chromosomes
• he did not have powerful microscope
• he studied pure plants

The map distance between the genes A & B is 3 units between B&C 10units and between C&A 7 units.The order of the genes in the linkage map constructed on the above data

• A,B,C
• A,C,B
• B,C,A
• B,A,C