A biologist counts 46 chromosomes in a human liver cell and estimates that a human has about 20,000 genes. What does this comparison show about how genes are arranged?

A fruit fly body cell holds 8 chromosomes, and researchers estimate the fly has about 14,000 genes. On average, roughly how many genes does one fruit fly chromosome carry?

Which list puts a gene, a chromosome and a nucleus in order from largest to smallest?

A corn plant cell holds 20 chromosomes and tens of thousands of genes. What must be true about where those genes are?

A chromosome is made of a long DNA molecule, and a gene is a section of that DNA.

Dog body cells hold 78 chromosomes. A geneticist searches them for the gene that controls coat length. What will she most likely find?

An onion body cell has 16 chromosomes while a human body cell has 46. What does the onion's smaller number tell you?

In one plant, the gene for flower color and the gene for leaf shape are mapped to two different positions on the same chromosome. What does this show about a chromosome?

In a human skin cell, where are the 46 chromosomes found?

A mouse egg cell holds 20 chromosomes, one from each pair, and together they carry about 20,000 genes. On average, about how many genes does each of those chromosomes carry?

A rabbit's fur color depends on dark pigment built by an enzyme, and one gene carries the instructions for that enzyme. A rabbit inherits two copies of a gene version that makes no working enzyme. What result is most likely?

One gene carries the instructions for hemoglobin, the protein that carries oxygen in red blood cells. A person inherits two copies of a version of that gene that builds hemoglobin molecules that stack together in rods. What trait follows?

The lactase gene carries instructions for an enzyme that breaks down the sugar in milk. A person inherits a gene version that stops producing lactase in adulthood. What is the likely result?

A trait such as fur color appears because of a chain that starts with a gene. What does a gene directly carry the instructions to build?

A gene builds a channel protein that moves salt out of the cells lining the airways. A person inherits two copies of a version whose protein does not work. What trait would follow?

A Siamese cat's pigment-making enzyme is coded by one gene and works only where the body surface is cooler. Where on the cat would you expect the darkest fur?

Wrinkled pea seeds hold extra sugar and very little starch. The gene involved codes for an enzyme in the seed. What best explains how this gene version causes wrinkled seeds?

Hair is built mostly from the protein keratin. A person inherits a gene version that produces keratin strands with a slightly different shape. What trait is that most likely to affect?

One gene carries the instructions for insulin, a protein that signals body cells to take sugar in from the blood. If working insulin is not made, what would you expect?

Different versions of the same gene can build slightly different forms of the same protein, which can lead to different traits.

A corn plant body cell contains 20 chromosomes arranged as 10 matching pairs. The plant grew from a fertilized egg. How many of the 20 chromosomes came from the pollen parent?

A human sperm cell carries 23 chromosomes and a human egg cell carries 23 chromosomes. How many chromosomes does the fertilized egg they form contain?

A puppy's body cells each hold 78 chromosomes. How many of those chromosomes did the puppy inherit from its mother?

Two students argue about a kitten. One says all its chromosomes came from its mother, and the other says half came from each parent. Whose claim matches how sexual reproduction works?

A fruit fly body cell has 8 chromosomes. How many chromosomes does one of that fly's egg cells carry?

Most human cells contain 46 chromosomes. Which human cells carry only 23 chromosomes instead?

A horse body cell holds 64 chromosomes arranged in 32 matching pairs. Where did the second chromosome of each pair come from?

A mutation changes one letter in the DNA of a rabbit gene, but the protein that gene builds still works exactly the same. What effect does this mutation have on the rabbit's traits?

A sunflower body cell has 34 chromosomes. How many chromosomes did the egg cell carry before it was fertilized and grew into that plant?

A mouse pup's body cells each contain 40 chromosomes as 20 matching pairs. How much did its mother contribute?

Two calves born to the same cow and bull have different coat patterns. Both carry the coat-pattern gene at the same position on the same chromosome. What best explains the difference?

Seeds from one pea plant grow into plants of several different heights. What process gives offspring of the same parent plant these differences?

A strawberry plant grows new plants along its runners, with no pollen and no fertilization involved. How do those new plants compare genetically with the parent plant?

Most traits, such as human height, are affected by many genes rather than by just one gene.

One kitten in a litter has a coat color that neither parent shows and no littermate shares. Scientists find a change in the DNA sequence of one gene. What is that change called?

A dog loses part of its tail in an accident. Later it has puppies with another full-tailed dog. What tail length would you expect in the puppies?

A student claims that offspring of the same two parents differ because of the mix of alleles each one inherits. Which observation best supports that claim?

A gardener grows a new plant from a cutting of a single parent plant, and it looks just like that parent. Which reasoning explains the result?

When a sow makes egg cells, what happens to each of her matching chromosome pairs?

Sheep in one flock share the same ram and ewe but differ in fleece color and horn size. Where does that variation among them come from?