Selective Breeding

What should be done to best ensure successful generations of offspring through selective breeding?

• breed organisms that are heterozygous for a recessive trait

• breed organisms that are homozygous for a recessive trait

• breed organisms that are homozygous for a dominant trait

• breed organisms that are heterozygous for a dominant trait

What is a disadvantage of this type of breeding?

• some genes are bred completely out of organisms which can decrease diversity

• it produces more variable offspring with new combinations of genes

• it increases the chances of mutations which can decrease diversity

• some genes are introduced into organisms that decrease mutations

Cystic fibrosis occurs when offspring inherit a copy of the recessive allele (f) from each parent, thus having a genotype of (ff). People with genotype (Ff) do not suffer from cystic fibrosis but can pass it on to offspring. What is the likelihood, expressed as a percentage, of a child inheriting cystic fibrosis if both the parents have genotype (Ff)?

• 25%

• 50%

• 75%

• 100%

Farmers in a community selectively breed cattle for certain traits they consider desirable. Answering which question would provide the BEST starting point for examining possible drawbacks of these farmers' artificial selection?

• Would removing species members that possess desired traits allow less "wanted" genes to pass to the next generation?

• Would species members be able to produce more milk through selective breeding for that trait?

• Would a species with less genetic diversity have more difficulty adapting to changing environments?

• Would species members be able to develop into larger sizes through selective breeding for that trait?

People discovered long ago that cross pollination of certain plant varieties could improve farm crops' flavor. Answering which question BEST helps people to produce crops with desired flavors?

• A Which genes in plants code for a sweet flavor?

• Which plants need to be selected for breeding to produce the best-tasting offspring plants?

• How does cross pollination produce unique offspring with different flavors?

• How does artificial selection of crops affect surrounding crops?

A mouse is placed at one end of a cardboard maze that has a piece of cheese at the other end. The mouse smells the cheese and learns how to find it. The mouse is using an

• acquired trait to gain an inherited trait

• inherited trait to gain an acquired trait.

• acquired trait to gain another acquired trait

• inherited trait to gain another inherited trait

A plant growing on a hillside has a stem that curves so that the plant is vertical. This curve is not observed in plants of the same species growing on level ground. Which statement BEST explains the curved stem of the plant growing on the hillside?

• It is a trait for which the plant has no genes.

• It is a trait that is usually detrimental to plant survival.

• It is a trait that developed in response to temperature variations.

• It is a trait that is only expressed under particular environmental conditions.

Researchers breed plants to produce crops that have helpful traits. One of these traits is the ability to grow where there is little moisture. How would this trait MOST likely benefit farmers?

• It allows crops to be unaffected by disease.

• It allows crops to be grown in drier climates.

• It allows crops to survive without fertilization.

• It allows crops to survive in areas with fewer seasons.

9. A new disease has decreased wheat crop production on a farm. In order to increase crop production again, which step should the farmer take? (S7L3c.)

• rotate different types of crops planted in the same area as the wheat crops

• select different types of wheat seeds and plant them all together to cross-pollinate

• plant the wheat in a different field where the soil has not been contaminated

• crossbreed wheat plants that are disease resistant with wheat plants with a high yield

Andrea divided a group of a species of insect she found in her backyard into two groups based on antenna size. The insects with short antennae produced offspring with short antennae. The insects with long antennae produced offspring with long antennae and short antennae. Which of the following statements is most likely true?

• The gene for short antennae is recessive and the gene for long antennae is dominant

• Length of antennae is random.

• The gene for short antennae is dominant and the gene for long antennae is recessive

• Length of antennae is not a hereditary characteristic.