Unit 5 AP Biology (Heredity)

Which organisms have ribosomes?

• Eukaryotes

• Prokaryotes

• Both

Answer explanation

All organisms have ribosomes. This is an ancestral trait. It emerged in the common ancestor so the common ancestor to all of life had ribosomes.

Cross between dihybrid and double recessive: what ratio do you expect?

• 1:1:1:1

• 1:2:1

• 9:3:3:1

• 12:3:1

Answer explanation

AaBb = ½ x ½ = ¼

Aabb = ½ x ½ = ¼

aaBb = ½ x ½ = ¼

aabb = ½ x ½ = ¼

Identify why many animals undergo plasticity

• Different genotypes

• Different ancestors

• Differential reproductive selection

• Different species

Answer explanation

Plasticity involves a phenotypic change due to an environmental change. This process will allow individuals to have a higher fitness.

Example: The snowshoe hare is able to blend into the snowly environment during the winter then the muddy environment during summer.

Tags

NGSS.HS-LS4-4

NGSS.HS-LS4-5

What moves apart during anaphase I of meiosis I?

• Homologous chromosomes

• Sister chromatids

Answer explanation

Meiosis I involves homologous chromosomes. During anaphase I, the homologous chromosomes that aligned on the metaphase plate during metaphase I are segregating to opposite poles.

A mutation in the mitochondrial DNA is from

• Father

• Mother

• Both parents

• Neither random occurrence

Answer explanation

The egg has all of the organelles for the zygote. This includes the mitochondria. If the mitochondria has a genetic issue, then that issue will occur in all of the offspring.​

Tags

NGSS.HS-LS3-2

Assuming complete dominance, what are the parents if the offspring have a 1:1 ratio?

• Homozygous recessive and heterozygous

• Homozygous recessive and homozygous dominant

• Heterozygous and homozygous dominant

• Heterozygous and heterozygous

Answer explanation

The homozygous recessive parent is only able to donate a recessive allele. This means that the half and half must result in another parent having one dominant and one recessive allele (heterozygous).

Tags

NGSS.HS-LS3-1

The type of inheritance where the phenotype is intermediate

• Codominance

• Complete dominance

• Incomplete dominance

Answer explanation

Neither allele is completely dominant. This results in a blending between the two dominant alleles to result in a different phenotype.

Example: Red X White --> Pink

With linked genes, how do recombinants form?

• Crossing over

• Independent assortment

• Random fertilization

• Transformation

Answer explanation

The two traits are found on the same chromosome. Crossing over will allow for the chromosomes to exchange genetic infomration between non-sister chromatids.​

For incomplete dominance, what phenotypic ratio do you expect in monohybrid cross?

Monohybrid by definition means two parents are heterozygous.

• 1:1:1:1

• 1:2:1

• 3:1

• 4:0

Answer explanation

As you see in the punnett square, there is

1 homozygous dominant (C^RC^R), 2 heterozgyous (C^RC^W), & 1 homozygous dominant (C^WC^W)

What type of inheritance?

• Autosomal Dominant

• Autosomal Recessive

• Sex-Linked Dominant

• Sex-linked Recessive

Answer explanation

When I look at pedigrees, I look whether the affected are in each generation or if it is able to skip generations. This example shows an affected individual in each generation which tells me DOMINANT.

Then, look for characteristics of sex-linked. In this one, you have an affected father with unaffected daughters. That is not possible since the father passing on his only X to his daughters. This tells us that it is AUTOSOMAL.

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2