PLZ HELP 10+ POINTS
6)
Which describes a trait from a recessive gene?
A) It causes a mutation.
B) It masks a dominant gene trait.
C) It can appear if it is heterozygous.
D) It usually appears only if it is homozygous.
7)
_______________, harmful or helpful, is considered to be the source for new alleles and a main contributor to the diversity of life on Earth.
A) Mitosis
B) Mutation
C) Transcription
D) Translation
8)
Scientists have changed the DNA of a type of cabbage so that it contains a tiny amount of poison from a scorpion’s tail. The poison in the cabbage kills caterpillars that try to eat it. This is an example of
A) gene therapy.
B) selective breeding.
C) genetic engineering.
D) artificial selection.
9)
There are four children in the Smith family. One child has blue eyes and blond hair. The other three children have brown eyes and blond hair. How can you explain this difference in eye color?
A) Brown eyes are the inherited trait; blue eyes are a mutation.
B) Eye color is an inherited trait; brown eyes are dominant over blue.
C) The brown eyed children have spent a lot of time outdoors; it's an environmental change.
D) The blue eyed child is younger than the children with brown eyes; their eyes will become brown.
Answers
6) D.( It can appear only if it is homozygous)
If it is heterozygous, dominant gene masks it's expression. So it should be homozygous to express.
7) B. (Mutation)
Mutation induces change in base pairs and hence it's expression changes. It brings about new variation in a polpulation.
8) C. (Genetic engineering)
It involves editing a gene by incorporating a new targeted gene to bring about desired changes. Here, gene of Cabbage is incorporated with scorpion's poison gene to make it pest-resistant.
9) B (Eye color inhertired trait and brown dominant)
Phenotypic ratio is 3:1 for any cross. For eye color, 3 childrens have brown eyes and 1 have blue which is in the same exact ratio. So we can conclude, One child is homozygous dominant brown, other 2 is heterozygous brown and one child homozygous recessive blue. So brown is dominant.
6. D
7. B
8. C
9. B
Hope it helps.