Exercises on the Either Rule

A rule of oris used to predict the probability of two or more random events occurring exclusively.

The occurrence of two mutually exclusive events is equal to the sum of the probabilities with which each event occurs.

We prepared a list of exercises on the rule of thumb orso you can test your knowledge of the probability of genetic events happening randomly.

You can consult the feedback and save this list of exercises in PDF at the end of the post!

Exercises on the Rule of or

1) An Rh+ couple with Rh- parents intends to have a child. Genetically, what is the probability that the child will be Rh- or be heterozygous for the trait in question?

a) 1/2.
b) 1/4.
c) 2/4.
d) 3/4.
e) 5/4.

2) (UFMS) Galactosemia is a disease that leads to problems in the metabolism of galactose and is caused by an autosomal recessive gene. For analysis, consider “G” for the dominant allele and “g” for the recessive allele. In this sense, a heterozygous man (Gg) married a heterozygous woman (Gg). Regarding the probabilities that the offspring of this couple will have galactosemia, mark the correct proposition(s).

01) It is expected that none of the offspring will have galactosemia.
02) It is expected that 50% of the offspring will be galactosemic.
04) It is expected that all offspring will have galactosemia.
08) It is expected that 25% of the offspring will be homozygous normal (GG).
16) It is expected that 100% of the offspring will be normal heterozygotes (Gg).
32) It is expected that 25% of offspring will have galactosemia.

3) Wonder flowers can be red, white or pink in color. These colors result from alleles that do not exert complete dominance over one another. The red flower is determined by the VV genotype, the pink VB and the white by BB. Imagine that a VB genotype plant crosses with a BB individual. What is the probability of having white or pink flowers?

a) 0%.
b) 25%.
c) 50%
d) 75%.
e) 100%.

4) If a couple has five children, the possibility of them being two of the same sex and three of another is:

a) 50%.
b) 37.50%.
c) 62.50%.
d) 20%.
e) 10%.

5) A woman is married to a man and would like to be a mother. A woman's blood, like a man's, is type AB. What is the probability that the child produced by this couple will have blood type A or B?

a) 1/2.
b) 1/4.
c) 1/6.
d) 1/8.
e) 1/32.

6) If we roll a die up, what is the probability of finding face 1 or face 5?

a) 1/2.
b) 1/4.
c) 2/6.
d) 1/8.
e) 1/32.

7) Albinism is a recessive anomaly characterized by the absence of melanin in the skin. A couple with a heterozygous genotype who have albino parents want to know the probability that their child will be born with albinism or be a carrier of the anomaly. Calculate this probability and mark the correct alternative:

a) 1/2.
b) 1/4.
c) 2/4.
d) 3/4.
e) 5/4.

8) If we toss two coins in the air, what is the probability of getting heads or tails?

to 1.
b) 1/2.
c) 1/4.
d) 3/4.
e) 1/8.

9) What is the probability that a couple will have a male and a female child in two different pregnancies?

a) 1/2.
b) 1/4.
c) 2/6.
d) 3/4.
e) 1/8.

10) To calculate the probability that a couple will have two pregnancies in which the two children are one female and one male, we must use:

a) the “and” rule.
b) “or” rule.
c) rule of “and” followed by rule of “or”.
d) rule of “or” followed by rule of “and”.

feedback

1 – d
2 - 08 and 32
3 – and
4 – c
5 – the

6 – c
7 – d
8 – the
9 – the
10 – c

Click here to save this list of exercises in PDF!

See too:

• List of exercises on biogeochemical cycles
• List of Exercises on the Oxygen Cycle
• List of exercises on intraspecific ecological relationships