Question 1

A mutation in DNA that changes the DNA sequence but does not alter the amino acid of a protein is known as ____________.

Accepted Answer

silent mutation. A silent mutation in DNA does not change the amino acid sequence of a corresponding protein.
Key Takeaway: In silent mutations, the DNA sequence is altered, but the resulting protein is not. This is the result of a level of redundancy in the mRNA code. Most amino acids can be coded by more than one codon, so a change in DNA does not always lead to a change in protein sequence.

Question 2

In an experiment, mice were infected with helminthes and observed for population change. It was found that mice became sickly and the population decreased. This relationship is an example of ________.

Accepted Answer

Parasitism. The helminthes prospered at the expense of the mice, resulting in a parasitic relationship.
Key Takeaway: Parasitism occurs in a relationship between organisms when one organism benefits at the expense of others. This is distinct from commensalism and mutualism. In commensalism, one organism prospers without any positive or negative effect on the other. In mutualism, both organisms benefit from the relationship.

Question 3

Plant cells differ from animal cells by the presence of _________.

Accepted Answer

Cell wall. Plant cells are surrounded by both a cell membrane and a thick outer cell wall, while animal cells are only surrounded by a cell membrane.
Key Takeaway: Plant cells and animal cells are strikingly similar in terms of content. Since plant cells have a rigid wall, they take more of a rectangular shape, whereas animal cells are generally round. Other key differences between plant cells and animal cells are the presence of the chloroplast in plant cells and the presence of the centriole in animal cells.

Question 4

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 5

Translation involves which two types of compounds ______________.

Accepted Answer

mRNA and protein. Translation is the process that produces proteins using mRNA as a template.
Key Takeaway: In translation, each three nucleotide sequence called a codon corresponds to a particular amino acid, or corresponds to a signal that starts or stops translation.
By knowing that translation involves the production of proteins, the student will be led directly to the answer.

Question 6

Red cabbage (Brassica oleracea capitata rubra) can be used as a natural pH indicator, its pigments change color in response to varying pH levels.Pigments can be extracted from the leaves of red cabbage, and relative pH can be determined by adding drops of a liquid into the pigment, as noted in the following table:pH 1-2 Pink/AcidpH 3-4 Dark Red/AcidpH 5-6 Violet/AcidpH 7-8 Blue/Neutral-BasepH 9-10 Blue-Green/BasepH 11-12 Green-Yellow/BaseWhat can a student determine about the red cabbage solution as a natural indicator of pH?

Accepted Answer

It turns pink in the presence of acids.
Key Takeaway: The table indicates that red cabbage solution changes colors based on the pH of substances added to it. Adding acids results in a change of color from blue to violet to red and eventually pink whereas adding bases results in a color change from blue to blue-green to greenish-yellow.
Photo: Red cabbage, by Rick Heath

Question 7

Which of the following is considered to be an endocrine gland?

Accepted Answer

testis. The testis produces and secretes the hormone testosterone.
Key Takeaway: An endocrine gland is an organ that produces and secretes hormones into the blood stream. This is opposed to exocrine glands such as the salivary gland. The salivary gland secretes substances into ducts. The heart, liver, and lung are all essential to life processes, but none secrete hormones into the bloodstream.

Question 8

Of the following, which of the groups below has the smallest number of species?

Accepted Answer

genus. Genus is the sixth level of classification, only followed by species.
Key Takeaway: The classification of organisms follows the following sequence: kingdom, phylum, order, class, family, genus, species. At the top of the classification, organisms only share general features. For example, all members of the Kingdom Animalia are eukaryotes, which differentiates them from bacteria. With each level down the classification system, organisms share more and more in common, thus reducing the number of species in each classification.

Question 9

Which of the following is the correct order of development of a fertilized egg?

Accepted Answer

zygote-morula-blastula-embryo. This is the development pattern of fertilized eggs in humans.
Key Takeaway: The zygote is formed when the egg fuses with the sperm, creating a single, diploid cell. The zygote then divides by mitosis until a solid ball of cells known as the morula develops.
Further development of this ball into a more organized state results in formation of the blastula. As development continues, cells of the inner core of the blastula go on to form the embryo. By only remembering that the zygote is the first stage and the embryo is the last stage, a student can eliminate three of the choices immediately.

Question 10

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 11

Blood typing can often be used to determine biological fatherhood. Three men, X, Y, and Z, are all possible fathers for child with bood type B. Blood testing determines that the mother's blood type is O. Which blood type must a candidate father have to be eliminated as a possible father?

Accepted Answer

A blood type. If the mother's blood type is O, the child must inherit the B blood antigen and blood type from its father. In this scenario, the father must have a B or AB blood type.
Key Takeaway: Blood type is inherited from both parents. A and B blood type are co-dominant over O blood type. Therefore, if one parent has O blood type, the child will receive the blood type based solely on the other parent. In this scenario, if the child's blood type was A instead of B, the child's father would have to have either A or AB blood type.

Question 12

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 13

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 14

Groups of species in a localized area are called:

Accepted Answer

Population. A group of species in a localized area form a population in the same manner humans in a city form a population.
Key Takeaway: Ecology studies interactions between individuals. Since it takes more than one organism to have an interaction, the basic ecological unit is the population. A population is a group of individuals that interbreed and share the same gene pool. Being members of the same species does not make all of those members a population. A population on exist if there is an intricate interact being the members of the species in an area.

Question 15

Which of the following organisms is classified in the phylum Chordata?

Accepted Answer

Dolphin. Dolphins are members of the phylum Chordata, who are characterized by having a notochord, a hollow dorsal nerve cord, and a post-anal tail.
Key Takeaway: Most chordates have are vertebrates, including humans. Crabs are arthropods, which are invertebrates with a hard exoskeleton. The octopus and squid are both types of mollusks, and the sea urchin is a type of echinoderm.

Question 16

Examples of _________ include ponds, grasslands, and forests.

Accepted Answer

ecosystem. The ecosystem is a natural unit consisting of all plants, animals, and microorganisms (biotic factors) in an area functioning in conjunction with the physical (abiotic) factors of the environment.
Key Takeaway: While ecosystem is often used interchangeably with biome, the terms define different areas. In short, a biome is comprised of numerous ecosystems. Like the ecosystem, the biome is a defined area of ecologically similar climatic conditions, but defined to a much larger area.

Question 17

RNA is composed of all of the following bases EXCEPT:

Accepted Answer

Thymine. Thymine is used as a nitrogenous base in DNA, but not RNA.
Key Takeaway: Both DNA and RNA use adenine, guanine, and cytosine as bases. However, DNA uses thymine as its fourth base, and RNA uses uracil as its fourth base.

Question 18

Which of the following is NOT an arthropod?

Accepted Answer

Tapeworm. An arthropod is an invertebrate with an exoskeleton (external skeleton), a segmented body, and joined attachments called appendages.
Key Takeaway: Arthropods are comprised of a diverse array of organisms, and are estimated to account for up to 80% of the known types of living species. Arthropods range from winged insects such as the bee to aquatic freshwater animals such as the lobster. Tapeworms are also invertebrates but do not possess an exoskeleton or a segmented body.

Question 19

If the father's blood type is AB and the mother's blood type is homozygous B, what is the percent likelihood that their offspring will exhibit type B?

Accepted Answer

50%. There is a three out of four chance that the child will have B blood type.
Key takeaway: Using the Punnett square, it is immediately evident that the child will only have B or AB blood type. The father can donate either an A allele or a B allele, whereas the mother can only donate a B allele. It is obvious that the child is 50% likely to have a B blood type.

Question 20

When oaks become the dominant plant in the area, the mixture of populations no longer creates changes in the environment. The community is now a climax community. Which of the following events could restart succession?

Accepted Answer

All of the above. A climax community is characterized by no environmental change without an outside stimulus.
Key Takeaway: In a climax community, the community has reached a point where the mixture of populations creates no new environmental changes. This equilibrium will not become unbalanced without some outside event. Fires, volcanic activity, human logging, and landslides are all examples of outside forces that can restart succession.

Quiz 1: Biology