Biology subject test (1)

NADH and FADH2 from the Krebs cycle enter the electron transport chain in the cristae, the inner membrane of the mitochondria?. The Krebs cycle does occur in the matrix of the mitochondr

MCAT Subject Tests

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Biology Subject Test 1

1 C6H12O6 + O2∅ CO2 + H2O

This process is completed

A in the cytoplasm

B in the area of the cell membrane

C in the nucleus

D in the mitochondria

E in the area around the ribosomes

2 Which statement about gastrulation is false?

A In the amphibian, the initial site of gastrulation

occurs at the gray crescent

B As a consequence of gastrulation the embryo now

consists of two germ layers: ectoderm and

endoderm

C In the amphibian, the infolding through which

blastula cells migrate during gastrulation is called

the blastopore

D The primitive gut that results from gastrulation is

called the archenteron

E Mesoderm develops during gastrulation

3 Which of the following associations of germinal tissues

and developed tissues is incorrect?

A Mesoderm : heart

B Ectoderm : nervous system

C Endoderm : intestinal tract

D Mesoderm : pancreas

E Ectoderm : epidermis of skin

4 Which of the following is not a type of genetic

mutation?

A Point

B Silent

C Insertion

D Frameshift

E All of the above are types of genetic mutations

5 Which of the following is a characteristic of tRNA?

A It is a long filament of RNA

B It is produced in the nucleolus

C It has a poly-A tail

D It has some short double-stranded segments

E It is the template for protein synthesis

6 Which is not a characteristic of proteins?

A Can self-replicate

B Can act as a hormone

C Can catalyze chemical reactions

D Acts in cell membrane trafficking

E Can bind foreign materials

7 A typical human gamete

A contains a haploid number of genes

B will always contain an X or Y chromosome

C is a result of the meiotic process

D has genetic material that has undergone recombination

E All of the above

8 All of the following organelles are membrane-bound except the

A rough endoplasmic reticulum

B Golgi apparatus

C nucleus

D mitochondria

E ribosome

9 Which statement about cyclic AMP (cAMP) is NOT true?

A cAMP is formed from ATP

B The enzyme that catalyzes the formation of cAMP

is adenylate cyclase

C The enzyme that catalyzes cAMP formation is generally located in the cytoplasm

D Membrane receptors are capable of activating the enzyme that forms cAMP

E cAMP is regarded as a second messenger, since it can trigger a cascade of intracellular reactions after a hormone binds to the cell membrane

10 All of the following about the Krebs cycle are true

EXCEPT

A the Krebs cycle occurs in the matrix of the

mitochondrion

B the Krebs cycle is linked to glycolysis by pyruvate

C the Krebs cycle is the single greatest direct source

of ATP in the cell

D citrate is an intermediate in the Krebs cycle

E the Krebs cycle produces nucleotides such as

NADH and FADH2

11 Which statement about glycolysis is NOT true?

A Glycolysis converts a single molecule of glucose

into two molecules of pyruvate

B Glycolysis can produce a net total of two ATPs

C The end-product of glycolysis can form ethanol,

CO2 lactate, and pyruvic acid

D During glycolysis FADH2 is produced

E During glycolysis NADH is produced

12 Which of the following statements about oxidative

phosphorylation is NOT correct?

A It occurs on the inner membrane of the

mitochondrion

B It involves O2 as the final electron acceptor

C It produces two ATPs for the FADH2

D It can occur under anaerobic conditions

E It involves a cytochrome electron transport chain

13 Glycogen

A is a storage polymer of glucose

B is found in both animals and plants

C is degraded by a process called glycogenesis

D is synthesized by a process called glycogenolysis

E is an unbranched molecule

14 In a cell that secretes large quantities of protein, such

as a pancreatic exocrine cell, there is (are)

I an abundance of rough endoplasmic reticulum

II a large Golgi apparatus

III prominent nucleoli

A I and II

B II and III

C I and III

D I only

E I, II, and III

15 Cells that are involved in active transport, such as cells

of the intestinal epithelium, utilize large quantities of ATP In such cells there are

A high levels of adenylate cyclase activity

B many polyribosomes

C many mitochondria

D high levels of DNA synthesis

E many lysosomes

16 The process by which a cell engulfs large particulate matter is called

A pinocytosis

B exocytosis

C cytokinesis

D phagocytosis

E osmosis

17 The genetic code is considered degenerate because

A more than one codon can code for a single amino acid

B one codon can code for multiple amino acids

C more than one anticodon can bind to a given codon

D only one anticodon can bind to a given codon

E None of the above

18 Which statement regarding protein synthesis is false?

A tRNA molecules shuttle amino acids that are incorporated into the protein

B tRNA molecules have the amino acid bound to the 3' end of the molecule

C The process does not require energy

D Ribosomal RNA is needed for proper binding of the mRNA message

E The message is read from the 5' end to the 3' end

19 Which statement about the cell plasma membrane is NOT correct?

A It serves as a selectively permeable barrier to the external environment

B It serves as a mediator between the internal and external environments

C In eukaryotes it contains the cytochrome chain of oxidative phosphorylation

D It contains phospholipids as a structural component

E It contains proteins that in some cases span the membrane

20 The basis for the pairing of the two strands of DNA in

the double helix is

A covalent bonding

B ionic bonding

C hydrogen bonding

D hydrophobic interactions

E hydrophilic interactions

21 Which statement about the lac operon is NOT correct?

A There are 3 structural genes that code for

functional proteins

B There is a gene that codes for a repressor protein

C The promoter is the binding site of RNA

polymerase

D The repressor protein binds to the operator,

halting gene expression

E The lac operon is found in leukocytes

22 Which of the following statements about enzymes is

NOT true?

A Their activity is unaffected by genetic mutation

B Enzymes may interact with non-protein molecules

in order to have biological activity

C Enzymes optimally operate at a particular pH

D Enzymes optimally operate at a particular

temperature

E Enzymes are almost always proteins

23 Bacteria have all the following organelles EXCEPT

A ribosomes

B a cell membrane

C a cell wall

D a nucleus

E a flagellum

24 An individual with type AB antigen on his red blood

cells, in an emergency

A may receive a transfusion of type O blood

B may receive a transfusion of type A blood

C may receive a transfusion of type B blood

D All of the above

E None of the above

25 Which of the following is a correct association?

A Mitochondria : transports materials from the nucleus to the cytoplasm

B Lysosome : digestive enzyme for intracellular use

C Endoplasmic reticulum : selective barrier for cell

D Ribosome : electron transport chain

E Polysome : group of Golgi complexes

26 Spermatogenesis and oogenesis differ in that

A spermatogenesis is mitotic while oogensis is meiotic

B oogenesis is mitotic while spermatogenesis is meiotic

C spermatogenesis produces gametes while oogenesis does not

D spermatogenesis produces four haploid sperm cells while oogenesis produces one egg cell and more than one polar body

E spermatogenesis involves unequal division of cytoplasm

27 If a male with blood type A marries a female with blood type B, which of the following types is impossible for a first generation child?

A Type B

B Type A

C Type O

D Type AB

E All types are possible

28 Polar bodies are formed during

A male mitosis

B female mitosis

C male meiosis

D female meiosis

E Two of the above

29 The ectodermal germ layers give rise to

A nails, blood vessels, and epidermis

B adrenal cortex and epidermis

C neurons and epidermis

D kidneys, blood vessels, and heart

E tooth enamel, blood vessels, and epidermis

30 Red is dominant over white in a certain flower Which

of the following is a valid way to test whether a red

offspring is homozygous or heterozygous in this

flower?

I cross it with a red plant that had a white parent

II cross it with a red plant that had two red parents

III cross it with a white plant

A I only

B II only

C I and III only

D II and III only

E I, II and III

31 Which of the following is not characteristic of

fermentation?

A Anaerobic

B Glucose requiring

C Energy producing

D Oxygen requiring

E Produces pyruvic acid

32 Which organelle is chiefly responsible for digestive

breakdown of the cell during autolysis?

A Pinocytotic vesicle

B Golgi body

C Ribosome

D Mitochondria

E Lysosome

33 Green (G) is dominant over yellow (g) in peas, and

smooth peas (S) are dominant over wrinkled peas (s)

Which cross must produce all green, smooth peas?

A GgSs x GgSs

B Ggss x GGSs

C GgSS x ggSS

D GgSs x GGSS

E None of the above

34 If 18O-labeled glucose is given to a rat, where will the

label first appear?

A Exhaled O2

B Exhaled CO2

C Exhaled H2O

D Plasma H2O

E Intracellular H2O

35 Which of the following cells doesn't have DNA in its nucleus?

A Phagocyte

B Epithelial

C Erythrocyte

D Paramecium

E Sperm

36 If two animals mate and produce viable fertile offspring under natural conditions, we can conclude that

A they both have haploid somatic cells

B they are both from the same species

C for any given allele, they both have the same gene

D their blood types are compatible

E None of the above

37 Which of the following is (are) derived from the mesoderm?

A Heart

B Lung epithelium

C Intestinal mucosa

D Nerve

E Two of the above

38 Ribosomes function in aggregates called

A histones

B nucleoli

C endoplasmic reticulum

D the Golgi complex

E polysomes

39 Unequal division of the cytoplasm occurs in

A production of sperm cells

B production of egg cells

C mitosis of an epidermal cell

D binary fission in bacteria

E None of the above

40 Which of the following is most likely to result in erythroblastosis fetalis?

A Mother is Rh- and embryo is Rh-

B Mother is Rh+ and embryo is Rh-

C Mother is Rh- and embryo is Rh+

D Mother and embryo are both Rh+

E Mother is Rh+ and father is

Rh-THE ANSWER KEY AND EXPLANATIONS BEGIN ON Rh-THE FOLLOWING PAGE

BIOLOGY SUBJECT TEST 1

ANSWER KEY

1 D

2 B

3 D

4 E

5 D

6 A

7 E

8 E

9 C

10 C

11 C

12 D

13 A

14 E

15 C

16 D

17 A

18 C

19 C

20 C

21 E

22 A

23 D

24 D

25 B

26 D

27 E

28 D

29 C

30 D

31 D

32 E

33 D

34 B

35 C

36 B

37 A

38 E

39 B

40 C

EXPLANATIONS

Respiration begins in the cytoplasm but is completed in the mitochondria The first step of respiration is glycolysis, which occurs in the cytoplasm Pyruvate from this reaction is converted to acetyl CoA, which enters the Krebs cycle in the mitochondria NADH and FADH2 from the Krebs cycle enter the electron transport chain in the cristae, the inner

membrane of the mitochondria

The in-pocketing of the blastula during gastrulation actually allows for the formation of the third cell layer, the mesoderm All the other answer choices are true

The ectoderm develops into the skin, the nervous system, and the eyes while the mesoderm develops into the

musculoskeletal system and the internal organs The endoderm develops into the digestive tract and is associated with organs such as the pancreas and liver, the respiratory tract, and the bladder lining The pancreas would therefore develop from the endoderm

Point mutations occur when a single nucleotide base is substituted by another A silent mutation is a point mutation that occurs in a noncoding region, or it does not change the amino acid sequence due to the degeneracy of the genetic code A frameshift mutation is either an insertion or deletion of a number of nucleotides These mutations have serious effects on the protein coded for, since nucleotides are read as series of triplets The addition or loss of nucleotides (except

in multiples of three) will change the reading frame of the mRNA

tRNA is a smaller type of RNA, which functions as a carrier of amino acid molecules Like mRNA, tRNA is coded for by DNA, but, unlike mRNA, it is a comparatively short ribonucleotide polymer instead of a long filament Although it

is largely single-stranded, there are short double-stranded segments in tRNA where the nucleotide chain loops back upon itself mRNA is actually the template for protein synthesis and has a poly-A tail, which plays a role in the degradation of mRNA rRNA is produced in the region of the nucleus known as the nucleolus

DNA is the only molecule capable of self-replication Some functions of proteins are as hormones (chemical

messengers), enzymes (catalyze chemical reactions), structural proteins (physical support), transport proteins (carriers of important materials), and antibodies (which bind foreign particles)

During meiosis, the gamete reduces its genetic component from 2n to n resulting in a haploid cell with half the normal chromosome number When a haploid egg and sperm unite they form a diploid organism known as a zygote All ova will contain an X chromosome and all sperm will contain either an X or a Y chromosome These gametes are formed during the two reductional divisions called meiosis During metaphase I of meiosis I, tetrads form and sister chromatids undergo homologous recombination known as crossing over

8 E

The ribosome, found in both prokaryotes and eukaryotes, can be found in the cytoplams or bound to the endoplasmic reticulum It is involved in polypeptide synthesis Membrane-bound organelles are found only in eukaryotes, and include the ER, Golgi apparatus, mitochondria, nuclei, and lysosomes

cAMP is a second messenger triggered after a receptor binds a ligand Ligands (such as hormones and

neurotransmitters) will bind their membrane receptors, activating it Through a G-protein intermediate the enzyme adenylate cyclase will be activated, and will covert ATP into cAMP Adenylate cyclase is attached to the inner layer of the phospholiped bilayer; it is not located in the cytoplasm cAMP is responsible for carrying the chemical stimulus into the cytoplam and triggering a response, and so is called a 2o messenger

The single greatest direct source of ATP in the cell is the electron transport chain The Krebs cycle does occur in the matrix of the mitochondria and oxidative phosphorylation (the electron transport chain) occurs in the inner membrane The final product of glycolysis is pyruvate, which is converted into acetyl coA for use in the Krebs cycle Citrate is an intermediate in this cycle (it is the first molecule formed; another term for the Krebs cycle is the Citric Acid cycle) The Krebs cycle only forms two ATP directly, all of the other ATPs that are formed are produced by oxidative phosphorylation (the nucleotides NADH and FADH2 donate their electrons to the electron transport chain)

Answer choice A is true because the first set of respiratory reactions are anaerobic and involve the breakdown of glucose into pyruvate Answer choice B is true because two ATP are required and four are produced leaving a net of two ATP Answer choice C is true because pyruvic acid, the final product of glycolsis can be anaerobically converted to lactic acid in humans and broken down to ethanol & CO2 in yeast (yeast are used to make alcoholic beverages and cause dough

to rise) Answer choice E is true because two NADH are produced by glycolysis and will donate their electrons to

compound Q in the electron transport chain Answer choice D is false, and therefore the correct answer, because FADH2

is not produced until the Krebs cycle

Oxidative phosphorylation occurs in the cristae of the mitochondria NADH and FADH2 donate their electrons to a series of cytochrome molecules and form an electron gradient, which forms a proton gradient This proton gradient drives

a proton pump that is coupled to an enzyme, which produces ATP The donated electrons are ultimately picked up by O2 and form H2O, one of the metabolic wastes of cellular respiration Each FADH2 from the Krebs cycle results in two ATP, while each NADH results in three ATP However, the NADH from glycolysis only produce two ATP due to the energy needed to get their electrons into the mitochondria from the cytoplasm

Glycogen is a storage polysaccharide sometimes known as animal starch It is made usually in the liver as a result of high glucose concentrations in the blood Answer choice B is incorrect because plants do not produce glycogen, rather they produce starch Answer choice C is incorrect because glycogen is degraded by a process called glycogenolysis, and answer choice D is incorrect because glycogen is synthesized by a process called glycogenesis Answer choice E is incorrect because glycogen is also a highly branched molecule

14 E

If a cell such as a pancreatic exocrine cell is producing large amounts of enzymes for export, lots of protein synthesis will be occurring in the rough endoplasmic reticulum (RER) This process will begin in the nucleus with the transcription

of lots of mRNA, which will be translated in the RER into polypeptides These polypeptides will be packaged and

modified in the Golgi for export out of the cell This cell would also have a large nucleolus as the nucleolus is the RNA source for the ribosomes

A cell that is involved in active transport, such as the epithelial cells of the intestine, will require large amounts of ATP If a cell utilizes large amounts of ATP, it must produce it in many mitochondria Answer choice A is incorrect because high levels of adenylate cyclase activity is found in cells that are the target cells for hormones Answer choice B is incorrect because many polyribosomes are found in cells that have a high level of protein synthesis Answer choice D is incorrect because high levels of DNA synthesis are found in cells that undergo rapid reproduction and mitosis Answer choice E is incorrect because many lysosomes would be found in phagocytic cells enabling them to digest the foreign material they've endocytosed

Phagocytosis is the process of engulfing large matter such as a bacterium Answer choice A is incorrect because pinocytosis is the process of taking in small amounts of liquid, and answer choice B is incorrect because exocytosis is the process of releasing proteins from the cell Answer choice C is incorrect because cytokinesis is the division of the

cytoplasm during mitosis, and answer choice E is incorrect because osmosis is the movement of water from an area of lower solute to an area of higher solute concentration

The degeneracy of the genetic codes describes how it is not precise or specific More than one codon can code for each of the different amino acids For example, both UAU and UAC code for tyrosine Since there are three bases in a codon, there are 64 possible codons and only 20 amino acids Obviously, there will be some repeating of amino acids among the codons Answer choice B is the opposite of answer choice A and therefore not true Answer choice C is incorrect because it is essential that the anti-codon be the exact base pair complement of the codon to maintain protein integrity Answer choice D is true, but not the definition of the degenerate genetic code

Protein synthesis does require energy Answer choice A is true because tRNA brings the amino acid to the ribosome where it interacts with the mRNA with the proper sequence Answer choice B is true because tRNA molecules do have the amino acid bound to their 3' end The mRNA is read from 5' to 3' as the ribosome moves along the message Answer choices D and E are both true

The plasma membrane separates the cellular contents from the environment and is responsible for the permeability of the membrane and what is allowed in and out The fluid mosaic model of the plasma membrane states that it is a bilayer

of phospholipid interspersed with proteins acting as receptors, pores, and channels The pores and channels cross the entire membrane The cytochrome chain is actually located in the cristae (the inner membrane) of the mitochondria