Heredity

How many chromosomes are in a haploid human cell? 23 46 48 92

23

An allele that can mask another allele is said to be __________. dominant homozygous recessive heterozygous

A dominant allele cannot be masked. Its trait will appear regardless of its partner allele on the other matching chromosome.

Which of the following is not a source of genetic variation? A) mitosis of fertilized egg B) independent assortment of chromosomes C) random fertilization of eggs by sperm D) crossover of homologous chromosomes

A) mitosis of fertilized egg Cell division by mitosis results in two daughter cells that are genetically identical to the parent cell.

Which of the following does not match the term to its correct definition/description? A) recessive: gene expressed when present B) genotype: genetic makeup of an individual C) heterozygous: two different alleles are present D) phenotype: physical appearance of an individual

A) recessive: gene expressed when present Recessive traits are only expressed if a person has two recessive alleles.

Use the following information to solve the problem using a Punnett square. Assume that the dominant "B" allele encodes brown eyes and the recessive "b" allele encodes blue eyes. An individual with the genotype BB has children by mating with an individual of the genotype bb. What is the percent chance that they would have children with blue eyes? 0% 25% 50% 100%

All the offspring would have brown eyes.

Some females have only one X chromosome, and their genotype is expressed as XO. There are living males with the genotype XXY and XYY, but none with genotype YO. What explains this difference? A) The genes on the Y chromosome cannot be activated without a gene on the X chromosome. B) The X chromosome has genes that encode for proteins that are essential for life, so a conception that resulted in an absent X would not be viable. C) None of the genes on the Y chromosome play a vital role in fetal development. D) The Y chromosome includes genes that are lethal unless balanced by a gene on the X chromosome.

B) The X chromosome has genes that encode for proteins that are essential for life, so a conception that resulted in an absent X would not be viable.

If two parents are heterozygous (Tt) for a trait, which of the following is NOT a possibility for their offspring? A) Half of the potential offspring would be genotypically different than the parents. B) Half of their offspring would be heterozygous. C) All of their offspring would be dominant for the trait. D) Most of the offspring would have the dominant phenotype.

C) All of their offspring would be dominant for the trait. One quarter of their potential offspring would be recessive for the trait.

A couple's first child has cystic fibrosis. The gene for cystic fibrosis is autosomal recessive, and the mode of inheritance is simple dominant/recessive inheritance. Neither parent has the disease. What are the odds that the couple's next child will have the disease? A) Zero, but their remaining children will all be carriers. A) Zero, because they have already had an affected child, so their next three children will not have the disease. C) All their children will have the disease because both parents carry the gene for cystic fibrosis. D) 1 in 4

D) 1 in 4 The scenario indicates that both parents are asymptomatic carriers. If you construct a Punnett diagram, you will find that the odds of any offspring of this coupling has a 1 in 4 chance of inheriting the two recessive genes, leading to the disease.

Sam has type A blood. The blood type of his partner is not known. Which of the following blood types are not at all possible among their offspring? A) type B B) type A C) type O D) All of the listed blood types are possible.

D) All of the listed blood types are possible. Depending on whether Sam is heterozygous with a recessive allele to donate or if he donates the A allele, all of the choices listed are possible for Sam's offspring.

Genes on the same chromosome are said to be __________. recessive homologous linked independent

Genes on the same chromosomes are said to be linked.

How many skin colors would there be if it was inherited in a simple recessive pattern rather than in a polygenetic fashion? At least four. Just as many as there are now. Two Three

In simple recessive inheritance, there are three possible genotypes and two phenotypes. Return to Assignment

Nuclear DNA is not the only source of genetic information in the cell. Which of the following is another source of DNA in the cell? mitochondria rough ER Golgi bodies nucleoli

Mitochondria have their own DNA separate from the nuclear DNA of the cell. Mitochondrial genes are transmitted to the offspring almost exclusively by the mother because the ovum donates essentially all the cytoplasm in the fertilized egg.

Which of the following is a noninvasive method for predicting genetic disease? choronic-villus sampling pedigree amniocentesis blood test

Pedigree analysis involves looking at phenotypic data from person's family tree to analyze whether or not an individual might be prone to a genetic anomaly.

Skin color, controlled by three separately inherited genes that each exist in two allelic forms (A, a; B, b; C, c), is an example of which form of inheritance? sex-linked inheritance multiple-allele inheritance dominant-recessive inheritance polygene inheritance

Polygene inheritance is the term that describes when multiple genes control one overall phenotype.

A fetal test to examine bits of placenta and perform karyotype analysis is _________________ sampling.

chorionic villus

The genetic makeup, or DNA sequence, of a person is their _______.

genotype

The 46 chromosomes of a cell displayed in homologous pairs is a ______________________.

karyotype

The genetic determination of blood type is based on __________ inheritance. sex-linked dominant-recessive polygene multiple-allele

multiple-allele There are three alleles for blood type.

The expression of a genotype, or the traits shown once proteins are produced, represent the _______________________.

phenotype