PCAT Biology Practice Test Answers
1:A Similar to green plants, certain bacteria are capable of using carbon dioxide (CO2) and water (H20) to synthesize carbohydrates. The pigments used by bacteria are more varied than the types of chlorophyll used by green plants. Bacterial photosynthesis does not take place in a chloroplast as it does in green plants. As is the case for all prokaryotes, bacteria lack internal membrane-bound structures, or organelles, such as chloroplasts or mitochondria. Thus, while many types of bacteria can carry out electron transport reactions to capture energy as part of the process of respiration, they do not do so in mitochondria. In contrast, some bacteria can, and some actually must, grow in the absence of molecular oxygen. Plants always require the presence of oxygen in order to capture energy from aerobic respiration.
2:C Eukaryotes are distinguished from prokaryotes primarily by the presence of a discrete intracellular compartment, the nucleus, which contains the cellular genetic material. The term ‘karyote’ comes from the Greek ‘karyon’ meaning kernel, referring to the nucleus. The prefix ‘pro'”‘ means ‘before,’ and the prefix ‘eu'”‘ means ‘good’ or ‘true.’ Both groups, however, have examples of multi- and unicellular organisms, such as certain bacteria, which aggregate to form complex structures, or yeast, a unicellular eukaryote. Similarly, there are both eukaryotes (plants) and prokaryotes (most, but not all bacteria), which have cell walls. Motility is a common feature of the cells of organisms within both groups.
3:A Glycogen is a polymer formed of repeating units of the monosaccharide glucose, which is commonly used by mammals to store energy. Sucrose, or table sugar, is a disaccharide'”thus, not a monomer'”derived from glucose and fructose; it must be converted to glucose monomers to be metabolized for energy or stored as glycogen. RNA is an information-carrying polymer composed of nucleotides (adenine, guanine, cytosine, and uracil). Proteins are polymers composed of a mixture of twenty amino acids arranged in such a way that the particular amino acid sequence and composition dictates the structure and function of the protein. In a similar way, lipids are complex polymers made up of mixtures of fatty acids, and the biological functions of lipids depend on their particular composition.
4:D Although there are certainly examples of cancers that are either a result of the expression of a recessive mutation (for example, the childhood eye tumor retinoblastoma) or an inherited predisposition to a particular cancer (such as in women who inherit a mutation that increases the likelihood they will develop breast cancer), most cancers are caused by mutations that occur spontaneously and, often, independently of inheritance. Similarly, there is good evidence that a few cancers, such as liver and cervical cancers, can be initiated by exposure to viruses, like hepatitis and human papilloma viruses, respectively. In these cases, however, as well as for most other human cancers, a series of genetic changes must occur for a cancer to become malignant and spread throughout the body.
5:C The production of oocytes, oogenesis, begins during fetal life in females. In contrast, males do not produce sperm until puberty. Both sexes respond to an increase in gonadotropin-releasing hormone (GnRH) by producing mature reproductive cells (sperm and secondary oocytes) that can participate in the process of fertilization. In both cases, the maturation processes for the gametes involve meiosis to produce haploid cells for the production of a diploid zygote. In addition, both sperm and oocyte production involve secondary cells (Sertoli cells and follicular cells, respectively).
PCAT Chemistry Practice Test Answers
1:A Acids and alcohols react to form esters by the elimination of the components of the water molecule from the two. In this reaction, the ‘”OH from the acid and the ‘”H from the alcohol ‘condense’ to form a molecule of HO-H, or H2O.
2:C Propanol is the alcohol H3CCH2CH2OH, molecular weight = 60 g/mole. Propanal is the aldehyde, H3CCH2CHO, molecular weight = 58 g/mole.
Propanone is the ketone H3CCOCH3, commonly known as acetone, molecular weight = 58 g/mole. All three are readily reactive molecules, and all three structures are based on a backbone of three carbon atoms. Only answer c) is true.
3:C The Br2/CCl4 test is the characteristic test for the presence of C=C and Câ‰¡C bonds in an organic compound. The color due to Br2 disappears as the Br2 adds across the double or triple bond to form the corresponding dibromo compound. For example, cyclohexene would react with Br2/CCl4 to produce colorless 1,2-dibromocyclohexane.
4:C This is a nucleophilic substitution reaction. The base extracts an ï¡ proton from 4-t-butylcyclohexanone to generate an enolate anion. This then acts as a nucleophile to replace the bromine atom of 1-bromobutane. The reaction ‘alkylates’ the 4-t-butylcyclohexanone molecule. The second equivalent of base allows the reaction to occur a second time, alkylating the cyclohexanone again on the opposite side of the carbonyl group.
5:C Friedel-Crafts reactions use strong Lewis acids to activate the benzene ring to the replacement of H atoms by alkyl or aryl substituent groups. The Lewis acid catalyst coordinates the ï° system of the benzene ring and the halide of the alkyl or aryl halide. This produces a good electrophile that can add to the benzene ring and displace a proton. The reaction can also be used for halogenation and acylation of benzene ring structures.
Claisen condensation involves the addition of an enolate ion to an ester with loss of H2O from the initial product to form an enone structure.Wittig reactions add a phosphine to a carbonyl group.
PCAT Reading Comprehension Practice Test Answers
1:D Paragraph 1 supports choice D as the correct answer. We can eliminate choices A and B because no mention is made of cholesterol causing either weight gain or weight loss (although we do know that excess weight may cause high cholesterol). We can eliminate choice C: although cholesterol is ‘useful in the production of vitamin D,’ there is no mention of ‘too much vitamin D.’
2:B The bulleted list supports choice B as the correct answer. We can eliminate choice A, as this is the function of HDL. The information in paragraph 1 allows us to eliminate choices C and D, as both LDL and HDL are apparently useful in cushioning the nerves and producing vitamin D.
3:C The bulleted list supports choice C as the correct answer. We can eliminate choices A and B, knowing that HDL transports cholesterol away from the arteries, not to them. We can eliminate choice D, knowing that this is the function of the liver.
4:C Paragraph 4 provides support for choice C as the correct answer. Choices A and B can be eliminated as being borderline or high. Choice D can be eliminated, as this is the healthy level of LDL, not total cholesterol.
5:A Paragraph 4 tells us that the correct answer is choice A. We can eliminate choice B, as this is the healthy level of HDL. We can eliminate C, as this is a healthy level of total cholesterol. We can eliminate D, as this is a high level of total cholesterol.
PCAT Quantitative Ability Practice
1:C Since each of the four runners ran a quarter mile, the total distance was one mile. Since one of the times given was 59 seconds, the easiest way to get the total time is to convert each of the other three times into minutes and seconds.
Now add the minutes and seconds for each of the four runners:
Convert 90 seconds to 1 minute 30 seconds and add to the other 3 minutes for a total of 4 minutes 30 seconds, or 4.5 minutes, to run 1 mile. To convert to miles per hour, set up a proportion:
Cross multiply to get
Â miles in 60 minutes, or
Â miles per hour.
2:D The formula for the volume of a cylinder is
, where r is the radius of the base and h is the height. The diameter is twice the radius, therefore the height of the cylinder in the problem is 2r. Substituting this in the formula, we get
3:A. To find the derivative of an equation, multiply the exponent of a term by its coefficient to form the new coefficient and reduce the value of the exponent by 1 to form the new exponent. A term that is a constant becomes zero when taking the derivative.
This is the first derivative. To get the second derivative, find the derivative of
This is the second derivative and the correct answer.
4:D Begin by multiplying both sides by 3 to eliminate the fractions:
Add 3 to both sides:
Divide both sides by 9:
Alternately, you may notice that each term in the numerator of the left side is divisible by three. You can factor the numerator and cancel the 3’™s before proceeding:
5:D By definition, the first derivative of
The first derivative of an equation is represented by the expression
There is no math to do in this problem. This simply requires you to remember trigonometric definitions and representations
PCAT Verbal Ability Practice Test Answers
1:B. The phrase ‘even though’ indicates that the introductory clause expresses an opposite idea from the main clause. The only answer choice that suggests the opposite of came back is digressed, which means ‘to depart temporarily from the main point’ or ‘to ramble.’
2:A Castigated, which means ‘rebuked severely,’ is the only word that makes sense in the sentence. Mollified means ‘soothed, appeased, or pacified.’ Abetted means ‘aided in wrong-doing.’ Cajoled means ‘coaxed with flattery.’
3:A Ask yourself what kind of child would refuse to obey his parents. The answer is: a stubbornly defiant one. Recalcitrant means ‘stubbornly defiant,’ so this is clearly the correct answer. A sedentary person spends a lot of time sitting and not moving about. A taciturn person does not talk much. Eclectic means ‘taking from various systems, sources, or doctrines.’
4:D. This is an analogy indicating types, since a eucalyptus is one type of tree, and an iris is one type of flower.
5.B. This analogy is based on synonyms. Just as facile and easy mean about the same thing, so do loquacious and talkative.