Which of the following statements about genes is incorrecto?
under norm. circumstances each chromosome contains one gene
What is a karyotype?
a display of every pair of homozygous chromos w/in a cell, organized according to size and shape
By examining a karyotype, it is possible to determine
which of two related plant forms is a gameotophyte, and which is a sporophyte
If the liver cells of an animal have 24 chromosomes, how many chromosomes do its sperm cells have?
Eu. sexual ife cycles show variation. Which do all sexual life cycles have in common?
meiosis, fertilization. and gametes
All of the following are functions of meiosis in plants except?
production of identical daughter cells
How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis?
They have 1/2 the numba of chromos. and 1/4 the amount of DNA
How does the sexual life cycle increase the genetic variation in a species?
by allowing ind. assortment of chromos, by allowing random fertilization, by allowing crossing over
For a species with a haploid # of 23 chromos, how many diff combinations of maternal & parternal chromosomes are possible for the gametes?
about 8 mill
Independent assortment of chromos. is a result of?
the random and ind. way in which each pair of homologous chromos. lines up at thee metaphase plate during meiosis I
Which of the following statements about crossing over is incorrecto?
Crossing over plays a role in both sexual and asexual repro.
The improvement of microscopy techniques in the late 1800s set the stage for the emergence of modern genetics b/c:
it allowed biologists to study meiosis and mitosis revealing the parallels between the behaviors of genes and chromosomes
When Morgan crossed the flies what was his explanation for this result?
The involved gene was on the X chromo.
What does a freq. of recombination of 50% indicate?
The two genes likely are located on diff. chromos.
A 0.1% frequency of recombination is observed?
in genes located very close to one another on the same chromosome
The reason that linked genes are inherited genes are inherited together is that?
they are located on the same chromosome
What is the mechanism for the production of genetic recombinations?
crossing over and ind. assortment
The frequency of crossing over between any two liked genes is
proportional is the distance between them
Males are more than affected by sex-linked traits than females b/c
males are hemizygous for the X chromosomes
One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome This is called a
One possible result of chromosomal breakage can be that a fragment reattaches to the original chromosome in a reverse orientation. This is called
A plant w/ pur. flowers is allowed to self-pollinate. Generation after generation, it produces purp. flowers. this is an example of
What is the difference between a monohybrid cross and a dihybrid cross?
A monohybrid cross involves organisms that are heter. for a single character where as a dihybrid cross involved organisms that are heter. for 2 characters.
Which of the following are true for alleles?
They can be identical or diff. for any given gene in a somatic cell. they can be dominant or recess.
What is the genetic cross between an ind. showing a dominant phenotype (unknown geno) and a homozy. recess. ind. called?
a testcross mother truckers
use of punnett squares?
predicting the result of genetic crosses between organisms of known genotypes
false regarding the law of segregation?
It is a method that can be used to determine the number of chromosomes in a plant
Skin color in a fishie is inherited via a single gene w/ four diff. alleles, how many gametes would be possible in this system?
what is sickle-cell disease?
substitution of wrong amino acids in the hemoglobin protein results in this disorder