Identify causes of deviations from simple Mendelian ratios.
• Discuss how environmental factors may affect phenotype.
• Explain how single genes can affect numerous phenotypic traits.
• Explain that some phenotypic traits are affected by several loci.
If two events are [blank_start]independent[blank_end] of each other, we use the product rule, and [blank_start]multiply[blank_end] their probabilities.
Answer
independent
multiply
Question 2
Question
What is the probability of getting an AaBbcc offspring from the cross of Aa BB Cc x Aa Bb cc?
Answer
50%
25%
12.5%
Question 3
Question
If you observed a 2:1 ratio for a gene in offspring, what could you assume?
Answer
One allele combination is lethal and so is never observed.
One allele combination never leads to a phenotype.
One allele combination is very rare.
Question 4
Question
Greater polymorphism in a population can be advantageous for survival and evolution.
Answer
True
False
Question 5
Question
Choose the incorrect statement about Incomplete Dominance.
Answer
Both alleles appear to be expressed equally by all cells, showing an intermediate phenotype which is neither.
A cross between two F1 individuals with a blended appearance of alleles will produce offspring in a 1:2:1 ratio, where 50% of the offspring have the phenotype of a blended appearance and the other 50% display single alleles.
It proves the blending inheritance theory.
Question 6
Question
Which statement best describes co-dominance?
Answer
Both alleles are expressed on the phenotype at the same time.
Neither alleles appear to be expressed on the phenotype, but instead an intermediate between them is seen.
Question 7
Question
The ABO blood antigen system is a good example of:
Answer
incomplete dominance
co-dominance
Question 8
Question
Epistasis describes the situation where one gene [blank_start]affects[blank_end] the action of another. Hence, if the gene to produce one enzyme in a [blank_start]metabolic pathway[blank_end] is damaged or ineffective, the next enzyme and gene in the chain may be perfectly [blank_start]function[blank_end] but will never produce an end product because their precursor is dysfunctional. The second gene is said to be under [blank_start]epistatic control[blank_end] of the first.
Answer
affects
metabolic pathway
functional
epistatic control
Question 9
Question
A phenotype controlled by many genes which have an additive effect is known as a [blank_start]_______[blank_end] trait, and example being [blank_start]______[blank_end].
Answer
polymorphic
polygenic
skin colour, weight, or height etc.
eye colour, hair colour, etc.
Question 10
Question
What is pleiotropy?
Answer
One gene having many phenotypic affects.
One gene affecting many other genes.
Many genes affecting the phenotype in a summative way.