Genes & Chromosomes
What is a gene?
A segment of DNA that contains information related to a trait or function.
A rabbit has genotype Gg. Is Gg its genotype or phenotype?
Genotype.
One parent produces offspring by copying genetic information without gametes joining. What type of reproduction is this?
Asexual reproduction.
Cross Aa × Aa. What fraction of offspring are predicted to be aa?
1 out of 4, or 25%
In a sample, 18 of 40 offspring are heterozygous. What percentage is heterozygous?
18 ÷ 40 × 100 = 45%.
Where are most genes found in a plant cell?
On chromosomes in the nucleus.
True or False: An organism's genotype refers to its physical, observable traits.
What is False?
(Genotype refers to genetic makeup/allele combinations, while phenotype refers to physical traits)."
True or False: Asexual reproduction involves the joining of gametes from two parents
What is False?
(Sexual reproduction involves gametes joining; asexual reproduction copies genetic information from one parent).
Two plants are both heterozygous (Rr). What is the probability that an offspring will also be heterozygous (Rr)?
What is 2 out of 4 (or 1/2, or 50%)?
A cross predicts 75% dominant phenotype, but a sample shows 71%. Does that automatically disprove the model?
No. Observed results can differ from predicted probabilities in a sample.
What is an allele?
A version of a gene.
For a fictional trait, P is dominant to p. Which genotype is heterozygous: PP, Pp, or pp?
Pp
Why can offspring from sexual reproduction show genetic variation?
They receive combinations of genetic information from two parents.
T is dominant for tall plants and t is recessive for short plants. Which genotypes can produce a tall plant?
TT or Tt
In a bar graph showing simulation data with 19 JJ, 42 Jj, and 19 jj offspring, which genotype bar is highest and represents the heterozygous outcome?
What is Jj?
A plant has genotype Bb. What do B and b represent?
Two versions (alleles) of the same gene.
Having two identical dominant alleles (AA) is homozygous dominant, while having two identical recessive alleles (aa) is known as this
What is homozygous recessive?
If no mutation occurs, how should a plant cutting's genetic information compare with its parent?
It is expected to be genetically identical to the parent.
Cross CC × cc. What genotype is predicted for every offspring?
Cc.
Why combine AA and Aa when calculating dominant phenotype under complete dominance?
Both genotypes express the dominant phenotype.
Why can root and leaf cells from the same plant contain genes related to fruit traits?
Ordinary nucleated body cells generally carry the plant's inherited genetic information, even though different cells use different parts of it.
Two plants have the same genotype but different heights after different watering. What can you conclude?
The height difference alone does not prove they inherited different alleles; environmental conditions can affect observable traits.
Can matching allele pairs at one gene prove two organisms were produced by the same reproductive process?
No. A match at one gene does not establish the entire genome or reproductive process.
What does a Punnett square predict, and what can it not guarantee?
It predicts possible offspring genotypes and probabilities; it does not guarantee exact counts in every sample
What is a stronger plan for testing an inheritance model than observing one offspring?
Make predictions, collect data from multiple offspring, compare results with predictions, and consider limitations.