Punnet Square
A flower shows codominance: R = red, W = white, RW = striped.
If two striped flowers (RW × RW) are crossed:List all possible genotypes of the offspring. Identify which genotypes produce striped petals.
Genotypes = RR, RW, RW, WW, striped = RW only.
Explain the main difference between sexual and asexual reproduction.
Sexual reproduction involves two parents and creates genetically diverse offspring, while asexual reproduction involves a single parent and produces genetically identical offspring
Why does meiosis produce haploid cells while mitosis produces diploid cells?
Meiosis includes two divisions that separate homologous chromosomes and then sister chromatids, reducing the chromosome number by half.
What is the backbone of the double helix structure of DNA made of?
Alternating sugar, deoxyribose, and phosphate groups, forming the "sugar-phosphate backbone"
Which genetic disorder is caused by an extra X chromosome in males (XXY)?
Klinefelter syndrome
A dominant allele T causes tall plants, but TT is lethal. Heterozygotes (Tt) are tall. A Tt plant is crossed with a tt plant. List all possible genotypes and which ones survive.
Genotypes = Tt, tt, surviving = Tt (tall), tt (short)
Why does sexual reproduction result in greater genetic variation?
A larger gene pool allows for greater diversity within the off spring
What is the main purpose of crossing over in Meiosis I, and during which phase does it occur?
Crossing over increases genetic variation by allowing homologous chromosomes to exchange segments of DNA. It occurs during Prophase I.
Where is the gene for colour-blindness located?
It is located on the X chromosome.
What is the main cause of chromosomal disorders like Down syndrome?
Nondisjunction
Petal color is determined by three alleles: R = red, Y = yellow, B = blue. R and Y = codominant - orange. R and B = codominant - purple. Y and B = codominant - green
Cross a plant RY with YB. List all possible genotypes and phenotypes of the offspring.
Genotypes: RY, RB, YY, YB
Phenotypes: Orange (RY) Purple (RB) Yellow (YY) Green (YB)
How does meiosis play a role in sexual reproduction?
Meiosis is the specialized cell division process in sexual reproduction that produces gametes and generates genetic diversity
Which phase of meiosis is most responsible for independent assortment?
Metaphase I
In the DNA sequence GACTGACTGACT, a mutation occurred and the piece of DNA then contained the sequence GACTTGACTGACT. What type of mutation is this an example of?
Insertion
What type of genetic disorder is caused by defects in the mitochondria and is inherited only from the mother?
Mitochondrial disorders
In a population of rabbits, fur color is controlled by incomplete dominance:
BB = black, Bb = grey, bb = white.
Two grey rabbits (Bb × Bb) are crossed.
List all possible genotypes of the offspring.
List all possible phenotypes.
If a breeder wants only black rabbits, what fraction of the litter is expected to be black?
Genotypes = BB, Bb, Bb, bb
Phenotypes = Black (BB), Grey (Bb), White (bb)
Fraction expected to be black = 1/4
Gametes are involved in which type of reproduction?
Sexual reproduction
Cytokineses usually, but not always, follows mitosis. If cells undergo mitosis and not cytokineses, what would this result in?
A single cell with 2 nuclei.
What is the difference between a chromosome and a chromatid?
A chromosome is the complete structure containing DNA and proteins, while a chromatid is one of the two identical halves of a chromosome that has been replicated.
What disorder is associated with fragile X syndrome, caused by a mutation on the X chromosome?
Developmental delays / intellectual disability
Petal color is determined by three alleles: R = red, Y = yellow, B = blue. R and Y = codominant - orange. R and B = codominant - purple. Y and B = codominant - green
Cross a plant RY with YB. List all possible genotypes and phenotypes of the offspring.
Genotypes = BB, Bb, Bb, bb
Phenotypes = Black (BB), Grey (Bb), White (bb)
Fraction expected to be black = 1/4
What is Binary fission? Is it considered sexual or asexual reproduction
Binary fission is when a parent cell splits into two identical daughter cells. It is considered asexual reproduction.
Explain how independent assortment during Metaphase I leads to genetic variation.
Homologous chromosomes line up randomly, so the maternal or paternal chromosome can go to either daughter cell. This random distribution creates many possible combinations of chromosomes, increasing genetic diversity.
What are linked genes and how do they impact crossing over?
Linked genes are genes closely located on the same chromosome that are usually inherited as a unit. This means there is a lower chance of crossing over occurring, because there is a smaller target area for breaking.
What type of mutation causes sickle cell anemia a change in DNA, chromosome, or proteins?
A change in the DNA (a point mutation)