Question 1

Which of the following is the site of protein synthesis?

Accepted Answer

Ribosomes. Translation, the process that converts mRNA code into protein, takes place in ribosomes.
Key Takeaway: Ribosomes are complexes of RNA and protein that are located in cell nuclei. Ribosomes catalyze both the conversion of the mRNA code into amino acids as well as the assembly of the individual amino acids into a peptide change that becomes a protein.

Question 2

Which of the following is a mammal?

Accepted Answer

Whale. Mammals are characterized by having mammary glands and giving birth to live young. Of the animals on this list, only whales fit that description.
Key Takeaway: Mammals are also characterized as being vertebrates. The chicken is a type of fowl, that like other fowl gives birth to hard eggs. The snake is a reptile, which gives birth to soft eggs. The grasshopper is an invertebrate insect with a hard exoskeleton. The protozoon is a unicellular organism without specialized cellular components.

Question 3

Which of the following is responsible for the coagulation of blood?

Accepted Answer

Platelets. Platelets are recruited to sites of injure and regulate the processes that lead to the formation of blood clots, or coagulation.
Key Takeaway: Platelets are irregular shaped cells that are unique in that they do not contain a nucleus. It is essential to health that the number of platelets is maintained at a proper level. A deficiency in platelets can lead to bleeding disorders, and too many platelets can result in aberrant clot formation within blood vessels, leading to stroke or heart attack.

Question 4

A scientist is studying the inheritance of two traits encoded by two different genes: eye color and hair color. Brown eye color is dominant of green eye color; brunette hair color is dominant over blond hair color. If parent A is homozygous for both brown eyes and brunette hair and parent B is heterozygous for brown eye color and brunette hair, what is the likelihood that an offspring will be born with green eyes and blond hair?

Accepted Answer

0%. In this scenario, it is impossible for an F1 offspring to have green eyes and blond hair.
Key Takeaway: Using the Punnett square, it is obvious that any offspring will inherit at least one copy of the genes for brown eye color and brunette hair from Parent A. Recessive traits only appear in the offspring when inherited from both parents. With these parents, offspring can only be homozygous or heterozygous for both brown eye color and brunette hair.

Question 5

Which of the following describes having three copies of a chromosome?

Accepted Answer

Trisomy. Chromosomes normally exist in pairs, having an extra chromosome is trisomy.
Key Takeaway: Disomy, or chromosomes that exist in pairs, is the normal chromosomal pattern. Monosomy is the condition of missing a chromosome, and trisomy is the condition of having an extra chromosome. Trisomy of the 21th chromosomal pair results in Down's syndrome. Tetrasomy and pentasomy refer to having four and five copies of a chromosome, respectively. Both generally occur only with the sex chromosomes.

Question 6

Over the course of 150 years, an area filled with weeds becomes more diverse and weeds are replaced by grasses, shrubs, and ultimately oaks. This process is defined as

Accepted Answer

Succession. Succession is the ordered shift in composition and structure of an ecological community.
Key Takeaway: Of the choices, only succession can define a change in an environment. Mutation, adaptation, divergence, and convergence all describe changes in an individual or group of organisms.

Question 7

As a means to spot prey, both snow leopards and owls have developed extraordinary night vision. This is an example of:

Accepted Answer

Convergent evolution. Both species have developed a similar characteristic for a similar purpose.
Key Takeaway: Convergent evolution occurs when two distinct species become similar in some way as a result of similar pressures. In the case of both the snow leopard and the owl, the pressure is the need for food. As nocturnal animals, both animals have evolved a distinct selection advantage which allows them to hunt at night and conserve energy that would be used during sunlight.

Question 8

What is the by-product of anaerobic respiration in muscle tissue?

Accepted Answer

lactic acid. In anaerobic respiration, pyruvate is ultimately converted to lactic acid.
Key Takeaway: Anaerobic respiration provides an avenue for organisms to produce energy in the absence of oxygen. Conversely, aerobic respiration requires oxygen.

Question 9

The transfer of genetic materal between a pair of chromosomes is called __________.

Accepted Answer

Translocation. Translocation, or crossing-over, is the transfer of genetic materal between neighboring chromosomes.
Key Takeaway: Translocation reactions can take place during meiosis when chromosomes are in close proximity during prophase I. Many genetic disorders and diseases are the result of translocations, so these events can be very deleterious to life.

Question 10

Which of the following factors does not influence human fertility rates?

Accepted Answer

The factor that does not influence human fertility rates is geography. Additional factors that influence human fertility include sexual behavior and instinct.
Key Takeaway: Human population growth is simply the difference in birth rates and mortality rates. When birth rates exceed mortality rates, the population grows, and when the converse occurs the population shrinks. The birth rate is closely linked to the fertility rate. Interestingly, many of the same factors that influence the fertility and consequently birth rate also affect the mortality rate. A decrease in per capita income tends to increase the mortality rate and decrease the birth rate.

Question 11

Which of the following pairs is not an example of analogous structures?

Accepted Answer

The pair that is not analogous is the arm of a chimpanzee and the flipper of a dolphin. Those are actually homologous structures.
Key Takeaway: Analogy occurs when two structures evolve independently in different species to perform the same function. This does not refer to similar structures in closely related species, but in species that are vastly different. These structures evolved over time as a result of convergent evolution, the process by which different species become more similar.

Question 12

What term describes the evolutionary process by which new species arise?

Accepted Answer

The evolutionary process by which new species arise is called speciation. Speciation can also be induced artificially under laboratory conditions or from animal husbandry.
Key Takeaway: There are four geographic modes of speciation in nature, based on the extent to which speciating populations are geographically isolated from one another: allopatric, peripatric, parapatric, and sympatric. As mentioned previously, speciation can also be induced artificially. A famous example is the mule, which was created by mating a male donkey with a female horse.

Quiz 1: Hesi: Biology