Dr. Reichlerıs Bio 301L  M-F 11:30am-1pm         Print Name:_________KEY____________

Exam #2   June 27, 2003

 

            Answer each question as succinctly as possible in the space provided.  If needed, continue on the back.  If you use a drawing as part of your answer, be sure to also include a written explanation.  Read each question carefully and donıt hesitate to ask if a question seems unclear.  These questions have specific answers, although for some, more than one answer is possible.  To receive full credit you must clearly and fully answer the question being asked.  Each question is worth 6 pts, unless otherwise noted, for a total of 100 points possible for this exam.

 

1.     What is one advantage and one disadvantage of using mitochondrial DNA to study human evolution?

Any one of:  Adv- only change via mutation, passed through mother

Disadv- can not trace male inheritance

 

 

2.     Why would the extraction of ancient human DNA help clarify evolutionary relationships between modern humans?

Could compare ancient and modern DNA to see how different or similar it is, and thereby trace movements of people.

 

 

3.     When studying ancient human DNA, it is commonly subjected to the Polymerase Chain Reaction (PCR).  What are two reasons for using PCR on ancient DNA?

To amplify small quantities, and to amplify specific regions such as only amplifying mtDNA.

 

 

3.     What cells in your body are undergoing meiosis?

The cells that produce gametes (sperm or eggs)

 

 

4.     Earlobe attachment is controlled by one gene with two alleles: (F)ree and (A)ttached.  Both of your parents have free earlobes, but you have attached earlobes.  Which allele is dominant?  (Show your work for partial credit.)

Free

 

 

Dr. Reichlerıs Bio 301L  M-F 11:30am-1pm  Exam #2   June 27, 2003  Print Name:_______Key_________

 

5.     If extra large corn was a recessive trait, how could you ensure that your entire corn crop was extra large?

Breed only extra large corn to each other.

 

 

6.     What are two factors that can make studying the relationships between genotypes and phenotypes difficult?  (8 pts)

Any two of:  Multiple genes control one trait, one gene controls multiple traits, environmental effects on expression of traits.

 

 

7.     Grizzly bears and black bears can produce viable offspring in captivity, but these hybrid offspring have never been seen in the wild.  Are grizzly and black bears the same species?  Why or why not?

No, even though they can reproduce, in nature they do not, and so they are not sharing gentic info.

 

 

8.     If a species reproduces only asexually, what type of environment might it live in?  Why?

A stable environment.  Asexual reproduction produces less diversity, but in a stable environment, diversity is not needed.

 

 

9.     In general, which would evolve more rapidly, cockroaches that reproduce every few days or humans who reproduce about every 20 years?  Explain.

Cockroaches would evolve more rapidly.  Evolution occurs via reproduction, and cockroaches reproduce more rapidly.

 

 

10.  Why is genetic diversity important for natural selection to occur?

Genetic diversity leads to different traits.  Some will be advantageous and others disadvantageous so that selection can take place.

 

Dr. Reichlerıs Bio 301L  M-F 11:30am-1pm  Exam #2   June 27, 2003  Print Name:_______Key__________

 

11.  How would an environment leading to stabilizing selection differ from an environment leading to directional selection?

Stabilizing would be a stable enviro, Directional would be a changing enviro.

 

 

12.  Diseases are often used as examples of catastrophes that cause evolutionary bottlenecks.  After a catastrophic disease, is the genetic make-up of the resulting population truly random?  Why or why not?

Either of:  If there is genetic resistance to the disease, only individuals with resistance will survive and pass on genes.  If resistance is not genetic, the population will be random.

 

 

13.  How do migrations affect evolution?

Introduce new alleles or genes.

 

 

14.  How might humans be affecting the rate of evolution?

If we are rapidly changing the environment, we could be changing how rapid species need to evolve.

 

 

15.  Is monogamy (having a single mating partner) evolutionarily advantageous or disadvantageous for humans?  Why?(8 pts)