Bio Test 4 TXST

Why do recessive X-linked traits occur more frequently and with greater severity in human males than in human females? Select all that apply.

1. Males have an X chromosome, but females do not. 2. In males, X inactivation shuts off expression of the alleles on one X chromosome. 3. Sperm are more likely to carry an X chromosome than a Y chromosome.

A healthy young couple are both carriers of cystic fibrosis; the chance that each of their future children will inherit this serious illness is

25%.

Jane is homozygous for a recessive "no-freckles" allele and has no freckles, while John is heterozygous and has freckles. The chances that their offspring will be homozygous recessive are _______ while the chances that their offspring will be homozygous dominant are _______.

50%; 0%

Which statement about human STDs is FALSE?

A person with a vasectomy is less likely to contract an STD.

Which of the following is transgenic?

A yeast cell that expresses a gene from a fish

Which statement is FALSE regarding stem cells?

Adult stem cell research is limited by law in the US.

Mendel was correct about most of what he postulated. Now that you know about sex chromosomes and sex-linked genes, which of these isn't always true?

All organisms have 2 of every gene.

Some goats have been altered to contain a gene from spiders for making silk. These goats are able to produce silk proteins in their milk that can be used to make a meshwork stronger than steel. We can say a lot about these goats - which of the statements below is false?

DNA sequencing was used to insert the foreign spider gene.

Identify the correct comparison in the genetic characteristics between embryonic and adult stem cells.

Embryonic stem cells can produce any of the differentiated cells, while adult stem cells can't.

A male expresses an X-linked recessive disorder only if he inherits alleles conferring the disorder from both parents.

False

Genotypes are the outward expression of an allele combination.

False

If a pea plant is heterozygous for yellow seeds (Gg), which gametes could it produce?

G or g

In the last year many false statements about GMOs have popped up on blogs and social media. Which one of these do we actually know to be true though?

GMO health testing is not mandatory in the US.

A diaphragm is a shallow, dome-shaped rubber disk with a flexible rim that fits within the vagina and covers the cervix. How does this act as a contraceptive to prevent pregnancy?

It would prevent sperm from reaching the egg.

Jane has the blood type A while John has the blood type AB. Jane has five children, but John is only the father of four. Which child is definitely not John's?

Jeb = genotype OO

Jane is a carrier for the recessive allele that causes cystic fibrosis and John is homozygous dominant. They want to have a child, but are concerned that it will be born with cystic fibrosis. Should they be worried?

No- it is impossible for them to have a child with cystic fibrosis.

The alleles for curly hair and straight hair exhibit incomplete dominance. If a child has straight hair, which of these could be true of her parents?

One has straight hair and one has wavy hair.

Which of the following is the correct path of an egg through the reproductive tract? Where would sperm be able to fertilize it?

Ovary --> uterine tube --> uterus; uterine tube

A vasectomy is a surgical procedure in which the vas deferens are severed, and then tied. How would this cause sterility?

Sperm cannot move to the urethra.

A male & female have been trying to conceive a child unsuccessfully. They learned from their doctor that this is because the male has a low sperm count. Why would low sperm count hinder fertility?

The enzymes from a large number of sperm are needed to dissolve the protective layer around an egg.

Why is it necessary for the testes to be in the scrotum to function properly?

The scrotum keeps the testes at a cool temperature which promotes sperm production.

A male treated for prostate cancer no longer has an intact prostate gland to contribute to semen, but his other glands & testes are still intact & he ejaculates normally. However, he and his partner are now unable to conceive a child. What might be going wrong?

The semen lacks the correct consistency and the sperm are unable to move freely.

During the cloning process, how much does the cloned offspring resemble the surrogate?

They share 0% of all genes.

A GMO is a transgenic organism.

True

Mendel's law of segregation states that the two alleles of each gene are packaged into separate gametes.

True.

In order for a girl to inherit hemophilia A, her parents would have which genotypes?

XHXh, and XhY

Menstruation occurs due to:

a decrease in estrogen and progesterone.

Having the alleles Tt is

a genotype.

The caplike _____ covers the head of the sperm and releases enzymes that will help the sperm penetrate the egg.

acrosome

This coding DNA may have different forms, or varieties, called _____

alleles.

A male expresses

both the dominant and recessive alleles on his X chromosome.

In females, nearly all cases of _____ cancer are associated with the human papillomavirus.

cervical.

If you were grading an exam on which a student had drawn and labelled a sperm cell, which label would lead to a loss of points?

cilia

In the biology lab, you observed that your lab partner's blood type is AB. The placement of the A and B molecules on each cell is controlled by proteins, coded by different versions of the same gene. Having both is an example of

codominant inheritance.

If disease symptoms are associated with a genetically inherited allele, tests can be performed

during all of these stages of life.

If an individual is heterozygous for a particular trait,

each parent contributed a different allele for that trait.

Apart from natural variation in a species, due to alternate alleles, abnormality (or disease) disorders are also of interest. Inheritance of autosomal dominant disorders requires ___ to pass on the allele, while inheritance of autosomal recessive disorders requires ___ to pass on the allele for it to be expressed in the offspring.

either the mother or the father; both the mother and the father

If asked to point to the place on a diagram where sperm cells are stored, you would place a pointer on the

epididymis.

A ____ is a series of nucleotides that codes for a protein product.

gene

A female who is a carrier for a harmful sex-linked gene will pass the gene to:

half of her male & half of her female offspring.

If the two alleles for a particular gene are identical the gene pair is

homozygous.

Preimplantation genetic diagnosis is one form of biotechnology associated with the fertility technology of

in vitro fertilization.

If the heterozygous phenotype is intermediate between those of the two different homozygotes, this is called

incomplete dominance.

All gametes contain

one set of chromosomes.

In biology lab, your class counts the number of people with different colors of hair and eyes. Your instructor says that these traits are variable and difficult to trace in each family. The reason is that these two traits depend on more than one gene, and are called

polygenic.

Many techniques in biotechnology have been restricted or limited by US government agencies and organizations. Which of the following currently has NO restrictions in the US?

preimplantation genetic diagnosis (PGD) of human embryos

If you were diagnosing a case of infertility in a male patient, and you found that his sperm failed to swim, you would diagnose a problem in the

prostate gland.

In the male, the saclike structure that contains the testes is the

scrotum.

The fact that the two alleles of each gene are packaged into separate gametes because they move apart from each other during gamete formation is Mendel's law of

segregation.

If a child develops a brain tumor that reduces LH and FSH production:

the child's puberty will be delayed or disrupted.

Genotype means

the combination of alleles in an individual.

Which of the following is FALSE regarding ovaries?

the corpus luteum develops just before ovulation

Phenotype means

the observable expression of the genes in an individual.

At a given position, homologous chromosomes have

the same genes but can have different alleles.

Cilia sweep the released mature oocytes from ovaries into the

uterine tubes.

No matter what else occurred, pregnancy would be impossible if a woman lost her

uterus.