Why does repeated selective breeding take generations?

• The selected parents must gradually change their own inherited alleles before breeding.
• The wanted trait must first become dominant before breeders can assess the offspring.
• Breeders must breed and assess offspring before selecting the next parents.

Which actions do breeders repeat when selecting for a heritable trait?

• Select suitable parents, breed them, assess offspring and select again.
• Select suitable parents, breed them, then keep offspring without assessing the wanted trait.
• Select suitable parents once, then let later generations breed without further selection.

Why can mating close relatives increase the risk of an autosomal recessive condition in their offspring?

• A harmful recessive allele becomes dominant when both parents have shared ancestry.
• They are more likely to share the same harmful recessive allele.
• An unaffected relative cannot carry the allele, so appearance identifies safe pairings.

Why is selecting unmodified E. coli insufficient to make them produce human insulin?

• They lack the human insulin-coding DNA that the engineering step supplies.
• They already carry human insulin-coding DNA, but selecting faster growth leaves it inactive.
• They already make human insulin, but selection cannot separate it from other bacterial proteins.

Scientists edit an existing maize DNA sequence in a laboratory without adding DNA from another species. Which statement fits?

• This is selective breeding because the change uses only DNA already present in maize.
• This is genetic engineering because the DNA is changed directly.
• This is selective breeding because genetic engineering requires DNA from another species.

Which pair gives a benefit and a concern for Bt maize?

• Less damage from certain pests; maize pollen could pass the allele to any nearby plant species.
• Protection from every insect pest; pollen could spread the allele to plants compatible with maize.
• Less damage from certain pests; pollen could spread the allele to compatible plants.

A herd has been bred from a few close relatives. Tests find a frequent harmful recessive allele. Which plan best targets this allele's risk in future calves while retaining other wanted traits?

• Use unrelated tested non-carriers and assess their other wanted traits before breeding.
• Use unrelated animals without allele tests and assess their other wanted traits before breeding.
• Use only fast, unaffected relatives without allele tests, keeping the herd's current breeding line.

A grower crosses unmodified cultivated wheat with compatible unmodified wild wheat and selects offspring. No DNA is directly edited or inserted in a laboratory. Is this genetic engineering?

• Yes. Combining DNA from cultivated and wild parents makes any such cross genetic engineering.
• No. Choosing crosses and offspring is selective breeding.
• Yes. Selecting a particular inherited trait counts as direct DNA editing even without laboratory work.