IMAT Examination Syllabus: Biology Practice Flashcards

Comprehensive practice flashcards structured around the Student Learning Outcomes (SLO) for all 13 topics in the IMAT Biology Examination Syllabus.

What are the exam parameters and scoring rules for the Biology section of the IMAT Examination?

The Biology section contains 23 questions, awarding 1.5 marks per correct answer and applying a penalty of -0.4 marks per wrong answer.

According to SLO 1.1.4, how do autotrophs and heterotrophs differ in how they obtain energy?

Autotrophs synthesize their own organic molecules from inorganic substances (such as via photosynthesis), whereas heterotrophs consume other organisms or organic matter for nutrition.

What are the three core principles of cell theory (SLO 2.1.1)?

1. All living organisms are composed of one or more cells. 2. The cell is the structural and functional unit of life. 3. All cells arise from pre-existing cells.

What key evidence supports the endosymbiotic theory for organelles like mitochondria and chloroplasts (SLO 2.1.2)?

Mitochondria and chloroplasts contain their own circular DNA, double membranes, 70S ribosomes, and replicate independently via binary fission similar to prokaryotes.

Why is the surface area to volume ratio significant for determining maximum cell size (SLO 2.1.3)?

As cell size increases, volume grows much faster than surface area, decreasing the ratio and limiting the rate at which nutrients and waste products can diffuse across the plasma membrane.

What roles do peroxisomes and glyoxysomes play as cellular microbodies (SLO 2.2.4)?

Peroxisomes break down fatty acids and neutralize harmful peroxides like hydrogen peroxide; glyoxysomes convert stored fats into carbohydrates in germinating plant seeds.

How do Gram-positive and Gram-negative bacteria differ in cell wall structure and Gram staining outcomes (SLO 2.3.1)?

Gram-positive bacteria have a thick peptidoglycan layer that retains crystal violet stain (appearing purple). Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane, losing crystal violet and counterstaining pink/red with safranin.

How do the lytic and lysogenic viral replication cycles differ (SLO 2.3.3)?

In the lytic cycle, the virus takes over host machinery to replicate rapidly, leading to host cell lysis. In the lysogenic cycle, viral DNA integrates into the host genome (as a prophage) and replicates silently along with host cell division.

What enzyme allows retroviruses like HIV to copy their RNA genome into DNA (SLO 2.3.4)?

Reverse transcriptase, which transcribes single-stranded viral RNA into double-stranded DNA for integration into host chromosomal DNA.

What is the fluid mosaic model of the cell membrane (SLO 3.1.1)?

It describes the membrane as a dynamic phospholipid bilayer with proteins, cholesterol, and carbohydrates embedded or attached, moving fluidly within the plane of the layer.

What are the main steps in the epinephrine signalling pathway (SLO 3.1.4)?

Epinephrine binds to a G-protein coupled receptor (GPCR), activating a G-protein that stimulates adenylyl cyclase to synthesize cyclic AMP ($\text{cAMP}$), which activates protein kinase A to initiate a cellular response cascade.

How does simple diffusion differ from facilitated diffusion across cell membranes (SLO 3.2.1, 3.2.2)?

Simple diffusion moves small, nonpolar molecules directly through the lipid bilayer down their concentration gradient without transport proteins. Facilitated diffusion uses specific transmembrane channel or carrier proteins to transport polar or charged molecules down their gradient without energy expenditure.

What analytical tests are used to detect reducing sugars and starch in carbohydrates (SLO 4.2.4)?

Benedict's test is used for reducing sugars (changing from blue to a green/orange/brick-red precipitate upon heating), and the Iodine test is used for starch (changing from yellow-brown to blue-black).

What interactions define the four levels of protein structure (SLO 4.3.2)?

Primary: sequence of amino acids linked by peptide bonds; Secondary: local alpha-helices and beta-sheets via backbone hydrogen bonds; Tertiary: 3D folding driven by R-group side chain interactions; Quaternary: association of two or more polypeptide subunits.

What are the structural differences between triglycerides, phospholipids, and steroids (SLO 4.4.1, 4.4.2, 4.4.3)?

Triglycerides contain one glycerol linked to three fatty acid chains; phospholipids contain one glycerol, two fatty acid chains, and a phosphate group; steroids consist of a fused carbon backbone made of four interconnected rings.

What components make up a DNA nucleotide (SLO 4.5.1)?

A nitrogenous base (adenine, thymine, cytosine, or guanine), a deoxyribose five-carbon sugar, and a phosphate group.

How do competitive and non-competitive enzyme inhibitors differ in mechanism (SLO 4.6.4)?

Competitive inhibitors bind directly to the enzyme's active site, competing with the substrate. Non-competitive inhibitors bind to an allosteric site elsewhere on the enzyme, altering its active site shape regardless of substrate concentration.

What roles do plasmids and restriction enzymes play in recombinant DNA technology (SLO 5.1.1)?

Restriction enzymes cut double-stranded DNA at specific recognition sequences, while bacterial plasmids serve as vectors to carry foreign DNA fragments into host bacterial cells for replication.

What are the three steps in each cycle of the Polymerase Chain Reaction (PCR) (SLO 5.1.3)?

1. Denaturation (heating to separate target DNA strands), 2. Annealing (cooling to allow primers to bind), and 3. Extension (heat-stable DNA polymerase synthesizes new complementary strands).

What molecules are separated and identified using Southern and Northern blotting techniques (SLO 5.1.4)?

Southern blotting detects specific DNA sequences, whereas Northern blotting detects specific RNA sequences.

What are the primary reduced electron carriers generated during cellular respiration (SLO 6.1.2)?

$\text{NADH}$ (derived from $\text{NAD}^+$) and $\text{FADH}_2$ (derived from $\text{FAD}$).

What is the location and net yield of glycolysis per molecule of glucose (SLO 6.2.1)?

Glycolysis takes place in the cytoplasm and produces a net yield of $2\text{ ATP}$, $2\text{ NADH}$, and $2\text{ pyruvate}$ per glucose molecule.

What reaction occurs during pyruvate decarboxylation in aerobic respiration (SLO 6.2.2)?

Pyruvate is transported into the mitochondrial matrix, loses a carbon as $\text{CO}_2$, reduces $\text{NAD}^+$ to $\text{NADH}$, and binds Coenzyme A to form Acetyl-CoA.

What are the end products of alcoholic fermentation versus lactic acid fermentation (SLO 6.3.2, 6.3.3)?

Alcoholic fermentation produces ethanol, $\text{CO}_2$, and regenerated $\text{NAD}^+$. Lactic acid fermentation produces lactate (lactic acid) and regenerated $\text{NAD}^+$.

Where do light-dependent reactions occur in chloroplasts, and what are their primary products (SLO 7.1.1, 7.1.2)?

They occur in the thylakoid membrane, producing $\text{ATP}$, $\text{NADPH}$, and $\text{O}_2$ (from photolysis of water).

What are the three main stages of the Calvin cycle (SLO 7.2.1)?

1. Carbon fixation (catalyzed by RuBisCO), 2. Reduction (utilizing $\text{ATP}$ and $\text{NADPH}$), and 3. Regeneration of the carbon acceptor $\text{RuBP}$ (ribulose-1,5-bisphosphate).

How do stable, labile, and permanent cells differ regarding cell cycle activity (SLO 8.1.4)?

Labile cells continuously divide throughout life. Stable cells are normally in $\text{G}_0$ phase but re-enter the cell cycle upon tissue damage. Permanent cells leave the cell cycle permanently and cannot divide after maturation.

How do crossing over and independent assortment generate genetic diversity in meiosis (SLO 8.2.2)?

Crossing over exchanges genetic material between non-sister chromatids of homologous chromosomes during prophase I; independent assortment randomly distributes maternal and paternal chromosomes into daughter cells during metaphase I and anaphase I.

What are Mendel's Law of Segregation and Law of Independent Assortment (SLO 9.1.1)?

The Law of Segregation states that allele pairs separate during gamete formation so each gamete carries only one allele. The Law of Independent Assortment states that alleles for different genes segregate independently of one another during gamete formation.

What experiment confirmed that DNA replication is semi-conservative (SLO 9.3.2)?

The Meselson and Stahl experiment, which cultured E. coli with heavy ($^{15}\text{N}$) and light ($^{14}\text{N}$) nitrogen isotopes and measured DNA density gradient centrifugation across successive cell divisions.

What three modifications occur during pre-mRNA processing in eukaryotic cells (SLO 9.3.4)?

1. Addition of a 5' cap (7-methylguanosine cap), 2. Addition of a 3' poly-A tail (polyadenylation), and 3. RNA splicing (removal of non-coding introns and ligation of coding exons).

What does degeneracy mean in the context of the genetic code (SLO 9.3.6)?

Degeneracy means that multiple distinct mRNA triplet codons can specify the same amino acid (e.g., 64 codons coding for 20 standard amino acids and stop signals).

What are telomeres and why are they necessary for eukaryotic chromosomes (SLO 9.4.4)?

Telomeres are repetitive non-coding DNA sequences at the ends of linear chromosomes that prevent chromosome degradation and chromosome fusion during cell divisions.

How is inducible gene regulation achieved in the lac operon (SLO 10.1.1)?

In the absence of lactose, the lac repressor binds to the operator and blocks transcription. When lactose is present, allolactose binds and inactivates the repressor, allowing RNA polymerase to transcribe the operon.

How is repressible gene regulation achieved in the trp operon (SLO 10.1.2)?

The trp operon is active by default. When tryptophan levels are high, tryptophan acts as a co-repressor that binds to the repressor protein, enabling it to attach to the operator and turn off transcription.

How do miRNA and siRNA regulate eukaryotic gene expression (SLO 10.2.3)?

MicroRNAs (miRNA) and small interfering RNAs (siRNA) bind to complementary sequences on target mRNA molecules, leading to mRNA cleavage or inhibition of translation.

What historical experiment demonstrated bacterial transformation (SLO 11.1.3)?

Griffith's experiment (1928), which showed that non-virulent R strain Streptococcus pneumoniae could acquire virulence from heat-killed virulent S strain bacteria.

What experiment proved that DNA, and not protein, is the genetic material of T2 bacteriophages (SLO 11.1.5)?

The Hershey-Chase experiment (1952), using radioactive phosphorus ($^{32}\text{P}$) to label viral DNA and radioactive sulfur ($^{35}\text{S}$) to label viral protein coats during bacterial infection.

How do homologous, analogous, and vestigial structures differ in evolutionary biology (SLO 12.1.1)?

Homologous structures share common ancestral origin but may serve different functions. Analogous structures perform similar functions due to convergent evolution without common ancestry. Vestigial structures are anatomical remnants that have lost their ancestral primary function.

What five conditions must be met for a population to remain in Hardy-Weinberg equilibrium (SLO 12.2.3)?

1. No mutations, 2. Random mating, 3. No gene flow (no migration), 4. Extremely large population size (no genetic drift), and 5. No natural selection.

What are the four primary types of animal tissues (SLO 13.1.1)?

Epithelial tissue, connective tissue, muscle tissue, and nervous tissue.

What electrical events produce the phases of a neuronal action potential (SLO 13.2.8)?

Depolarization occurs when voltage-gated $\text{Na}^+$ channels open allowing sodium influx. Repolarization occurs when $\text{Na}^+$ channels close and voltage-gated $\text{K}^+$ channels open allowing potassium efflux. Hyperpolarization occurs before resting potential ($-70\text{ mV}$) is restored by the $\text{Na}^+/\text{K}^+$ ATPase pump.