Biology Exam Questions and Answers

5.) True or false? Under the biological species concept, barriers to reproduction between heterospecific individuals can occur only before fertilization takes place.

My Answer (True): Under the biological species concept, barriers to reproduction between heterospecific individuals can occur only before fertilization takes place.

Correct Answer (False): Under the biological species concept, barriers to reproduction between heterospecific individuals can also occur after fertilization takes place.

Explanation: Upon first reading the question, I was confused by the heterospecific wording as I began to think about asexual versus heterospecific reproduction. Barriers to reproduction can occur after fertilization takes place as the complications could arise preventing the reproduction of that specific zygote. 

7.)  Which statement (or statements) accurately describe a postzygotic barrier to reproduction?

My Answer (A): A postzygotic barrier can block fertilization by causing mating attempts among heterospecific individuals to fail. 

Correct Answer (c): A postzygotic barrier can block fertilization by causing hybrid offspring to be nonviable or sterile. 

Explanation: When reading the question, I was again focused on the heterospecific concept. I had failed to recall that a postzygotic barrier can only occur after an embryo has been implanted and not before. This barrier would not occur during mating attempts as the postzygotic barrier occurs after eggs have already been fertilized. If the fertilized eggs are unable to survive we would then have a postzygotic barrier.  

9.) True or false? Bishop pines and Monterrey pines coexist in regions of southern California. In a greenhouse is it possible to show that the two species can interbreed and that the hybrids are fertile. However, in nature, Bishop pines and Monterrey pines never interbreed because they pollinate at different times of the year. As referred to in A Botany of Desire, this is an example of a prezygotic barrier to reproduction. 

My answer  False): Bishop pines and Monterrey pines coexist in regions of southern California. In a greenhouse is it possible to show that the two species can interbreed and that the hybrids are fertile. However, in nature, Bishop pines and Monterrey pines never interbreed because they pollinate at different times of the year. This is not an example of a prezygotic barrier to reproduction.

Correct Answer (True): Bishop pines and Monterrey pines coexist in regions of southern California. In a greenhouse is it possible to show that the two species can interbreed and that the hybrids are fertile. However, in nature, Bishop pines and Monterrey pines never interbreed because they pollinate at different times of the year. This is an example of a prezygotic barrier to reproduction

Explanation: I confused the concepts of pre and postzygotic barriers as evidence by my answer to question 7. In this case, the inability of the pines to interbreed is a prezygotic barrier to reproduction as this barrier occurs before an egg has been fertilized. Had the fertilization already occurred it would have been a postzygotic barrier.

13.) Which statement accurately describes a mechanism by which sympatric speciation can occur? 

My answer (A): Hybridization of two species in which the hybrids survive and/or reproduce better than either parent species in a particular environment.

Correct Answer (D): All of the above.

Explanation: I selected only one of the options because I was not entirely sure that sympatric speciation produced allopolyploids which have chromosomes from a different set of species. This concept threw me as I thought sympatric speciation occurred from a single set of species. 

16.) Which statement accurately describes the focus of taxonomy?

My Answer (A): Taxonomy focuses on understating evolutionary relationship among organisms.

Correct Answers (B): Taxonomy focuses on the naming and classification of organisms. 

Explanation: As throughout the exams the questions and topics were focused on evolution I came into this question with the evolutionary mindset. I was unable to recall that taxonomy was related to the classification of all organisms, such as the Canis Latrans, and was not necessarily an evolutionary concept.

17.) Which statement accurately describes the focus of cladistics?

My Answer (B): Cladistics focuses on the naming and classification of organisms. 

Correct Answers (A): Cladistics focuses on understanding evolutionary relationships among organisms.

Explanation: As in the previous question I confused the concept of cladistics and taxonomy as I believed taxonomy was the one related to evolution. However, cladistics focuses on evolutionary relationships rather than classification.

30.) True or false? Basing a phylogenetic tree on similarities among DNA sequences ensures that it an accurate depiction of evolutionary relationships.

My Answer (True): Basing a phylogenetic tree on similarities among DNA sequences ensures that it an accurate depiction of evolutionary relationships.

Correct Answer (False): Basing a phylogenetic tree on similarities among DNA sequences ensures that it is not an accurate depiction of evolutionary relationships.

Explanation: By not remembering the concepts of taxonomy and cladistics I was unable to accurately answer this question. As the term phylogenetic had the term genetic within the name I assumed DNA was prevalent in the concept. However, a phylogenetic tree is both a taxonomy and cladistics tool as it classifies evolution.   

42.) Which statement accurately describes transduction?

My Answer (D): Transduction is the process by which DNA is transferred between two bacteria that are temporarily joined by a pilus. 

Correct Answer (C): Transduction is the process by which bacteriophages carry prokaryotic genes from one bacterium to another.

Explanation: I originally thought of transduction as a process through which DNA is transferred so when I saw DNA in the wording of the response I chose that answer. I have learned that the concept of transduction exists in multiple scientific disciplines and is not just related to genetics.

44.) True or false? The F-factor is always carried on an F-plasmid.

My Answer (True): The F-factor is always carried on an F-plasmid.

Correct Answer (False): The F-factor is always carried on an F episome.

Explanation: I confused the concepts of plasmid and episome. Also, I did not fully relate the transduction process to bacteriophages carrying genes from one bacterium to another which is similar to the F-factor process. By not fully understanding this concept I was unable to accurately answer these questions.

45.) Which statements accurately describes a bacterium that is an obligate anaerobe?

My Answer (B): An obligate anaerobe can use O2 to carry out aerobic respiration if there is sufficient O2 in the environment; alternatively it can use glycolysis and fermentation or anaerobic respiration if there is not sufficient O2 in the environment. 

Correct answer (C): An obligate anaerobe lives an environment where O2 is largely absent must use glycolysis and fermentation or anaerobic respiration because O2 is toxic.

Explanation: I understood the concept of an obligate anaerobe of being related to oxygen however I misunderstood the relationship that existed. While I thought it was about the presence of oxygen the bacterium has to be able to exist in an environment without oxygen. 

46.) Which statement accurately describes a bacterium that is a chemoautotroph?

My Answer (C): A chemoautotroph uses organic chemicals as a source of energy to build organic molecules such as polypeptides from other organic molecules. 

Correct Answer (A): A chemoautotroph uses inorganic chemicals such as H2S as an energy source fix CO2 into three-carbon sugars that can be used to build glucose.

Explanation: I was able to recall chemoautotroph as a process through which energy is produced however I confused the way in which the energy is created. As the process occurs through oxidation I believed I was accurate in stating that organic chemicals are utilized however the correct answer of inorganic chemicals now makes sense to me.

48.) Which of the following is not a major clade (supergroup) within the domain Eukarya.

My Answer (A): Uniknonta

Correct Answer (E): None of the above.

Explanation: I did not recall Uniknonta as one of the major clades. I had assumed Uniknonta was its own domain. Looking back at the other responses I was sure that they existed within the domain Eukarya.

52.) Which supergroup includes animals and fungi, as well as slime molds and amoebozoans? 

My Answer (D): Excavata

Correct Answer (A): Unikonta

Explanation: Again I confused Uniknonta as a domain rather than a major clade. This confusion resulted in an incorrect answer for this question as well as number 48.  

55.) True or false? Within the Eukarya, many unicellular organisms such as apicomplexans, chlamydomonads, and cellular slime molds have a life cycle in which the haploid form is represented only as a zygote.

My Answer (False): Within the Eukarya, many unicellular organisms such as apicomplexans, chlamydomonads, and cellular slime molds do not have a life cycle in which the haploid form is represented only as a zygote.

Correct Answer (True): Within the Eukarya, many unicellular organisms such as apicomplexans, chlamydomonads, and cellular slime molds have a life cycle in which the haploid form is represented only as a zygote.

Explanation: As seen in the other questions surrounding Eukayra I did not fully understand this concept. I thought of the life cycle process in which the haploid form could be represented in multiple other ways rather than a zygote such as with a sporophyte. 

59.) All land plants exhibit a characteristic termed alteration of generations. Which of the following is a feature of alteration of generations?

My Answer (B): A multicellular, diploid sporophyte that produces haploid spores via melosis. 

Correct Answer (D): All of the above.

Explanation: I thought of the question in a much different aspect of alteration of generations. As the haploid spore is different from the diploid sporophytes I believed this was the accurate response. Also, I did not think that C in which an embryo was discussed was an accurate depiction of an alteration of generations which was why I ruled out all of the above as a response.

60.) Which of the statements accurately describes apical meristems in land plants?

My Answer (E): B and C. 

Correct Answer (D): A and B.

Explanation: I did not think that apical meristems contained undifferentiated cells which were why I ruled out A. As mitosis is a regular process in other meristems I thought the process would be different in apical meristems which were why I opted for B and C.