Genetic Disorders
What disease typically causes death shortly after birth?
Edwards Syndrome
What is the genotype ratio for a heterozygous × heterozygous monohybrid cross?
1:2:1
Meiosis results in cells which are?
Haploid
Explain incomplete dominance
In incomplete dominance, the heterozygous phenotype is a blend of the two homozygous phenotypes, e.g., red and white flowers producing pink flowers.
What is the main difference between asexual and sexual reproduction in terms of offspring?
Asexual produces genetically identical offspring; sexual produces genetically unique offspring.
Why does Nondisjunction increase with time?
As even while dormant eggs degrade over time which leads to the development of Genetic Disorders.
If you cross two heterozygous tall pea plants (Tt × Tt) and tall is dominant, what is the phenotypic ratio of tall to short offspring?
3:1
When does cytokinesis happen in meiosis?
During the end portion of telophase I.
What is codominance?
Both alleles are expressed equally in the heterozygote, e.g., AB blood type.
Why is genetic variation important for a species?
It helps species survive environmental changes and resist diseases.
What is the cause of down syndrome?
Down syndrome is caused by a chromosomal abnormality where a person has a extra copy of chromosome 21.
In a dihybrid cross of TtRr × TtRr, what fraction of offspring will be homozygous recessive for both traits?
1/16
“This process, occurring during metaphase I, states that the orientation of each homologous chromosome pair is random, contributing to genetic variation.” What is this called?
Independent Assortment
Why is there a range of heights rather than just tall or short?
Multiple genes contribute to height, and their combined effects plus environmental factors create a continuous range of phenotypes. Causing continuous variation.
What is one type of asexual reproduction common in unicellular organisms?
Binary Fission
What causes sickle cell anemia?
The substitution of one instance of adenine with thymine
What principle explains that alleles for different traits separate independently in gamete formation?
Law of Independent Assortment
This phase of meiosis I is where homologous chromosomes pair up to form these structures. What are the structures called?
Tetrads
When a trait is controlled by two or more genes.
Polygenic Inheritance
Why is regeneration considered a form of asexual reproduction?
Because the new organism develops from one parent and is genetically identical.
What genetic disorder causes mucus buildup in the lungs?
Cystic Fibrosis
A cross between AaBb x AaBb gives what phenotypic ratio for the offspring?(A and B re both dominant traits)
9:3:3:1
What is the centromere responsible for?
holds sister chromatids together until Anaphase II and is also the site where crossing over occurs during Prophase I
A cross between two pink flowers (Rr, incomplete dominance) is performed. What fraction of offspring will be red, pink, and white?
-RR = red, Rr = pink, rr = white
-Punnett square: 1 RR : 2 Rr : 1 rr → 25% red, 50% pink, 25% white
What is sporulation?
Asexual reproduction where organisms produce spores that develop into new individuals.