A fern plant you are experimenting with can have one of two phenotypes for the surface its
leaves. The leaf surface can be fuzzy or it can be smooth. The phenotype is under the control of a
single gene designated as Fz. The dominant phenotype is smooth leaf surfaces, and the recessive
is fuzzy leaf surfaces. You are growing a plant that is heterozygous (Fz fz), and you suddenly
notice that all the leaves that grow from a new, young branch are fuzzy. You use your knowledge
of the fern\'s biology to determine that the leaves are fuzzy because all their cells have the
genotype fz fz. You suspect that mitotic crossing over has occurred as this plant has been
growing. An observation that would support your hypothesis would be to find that:
A. the cells of leaves on an adjacent branch are all homozygous dominant.
B. the cells on an adjacent branch are all homozygous recessive.
C. the cells on adjacent root are all homozygous recessive.
D. the cells of the leaves on an adjacent branch are all heterozygous.
Solution
A. the cells of leaves on an adjacent branch are all homozygous dominant.
It has been observed that crossing-over occurs at mitosis when homologous segments will get
paired accidentally in asexual cells.
During this, a part of the chromosome will get exchanged.
So, when chromosomes carrying Fzfz has paired up, the exchange of genetic material has
resulted in two cells, one is homozygous dominant FzFz and another one is homozygous
recessive fzfz, so the branch which rised from this cell carrying fzfz homozygous recessive
combinations will have fuzzy leaves.
So the cells of the leaves on the adjacent branch surely will have all homozygous dominant
combination of genes FzFz..
A fern plant you are experimenting with can have one of two phenotyp.pdf
1. A fern plant you are experimenting with can have one of two phenotypes for the surface its
leaves. The leaf surface can be fuzzy or it can be smooth. The phenotype is under the control of a
single gene designated as Fz. The dominant phenotype is smooth leaf surfaces, and the recessive
is fuzzy leaf surfaces. You are growing a plant that is heterozygous (Fz fz), and you suddenly
notice that all the leaves that grow from a new, young branch are fuzzy. You use your knowledge
of the fern's biology to determine that the leaves are fuzzy because all their cells have the
genotype fz fz. You suspect that mitotic crossing over has occurred as this plant has been
growing. An observation that would support your hypothesis would be to find that:
A. the cells of leaves on an adjacent branch are all homozygous dominant.
B. the cells on an adjacent branch are all homozygous recessive.
C. the cells on adjacent root are all homozygous recessive.
D. the cells of the leaves on an adjacent branch are all heterozygous.
Solution
A. the cells of leaves on an adjacent branch are all homozygous dominant.
It has been observed that crossing-over occurs at mitosis when homologous segments will get
paired accidentally in asexual cells.
During this, a part of the chromosome will get exchanged.
So, when chromosomes carrying Fzfz has paired up, the exchange of genetic material has
resulted in two cells, one is homozygous dominant FzFz and another one is homozygous
recessive fzfz, so the branch which rised from this cell carrying fzfz homozygous recessive
combinations will have fuzzy leaves.
So the cells of the leaves on the adjacent branch surely will have all homozygous dominant
combination of genes FzFz.
