JAN 2023 P2

Question 41

• The answer is D. Golgi apparatus
• Glycosylation is the process of adding carbohydrates to proteins or lipids
• The Golgi apparatus is responsible for processing and packaging proteins, including glycosylation
• Abnormal glycosylation patterns suggest a defect in the Golgi apparatus

Question 42

• The answer is B. Sweating during a yoga class
• Basic nervous system functions are involuntary and essential for survival.
• Sweating is a reflex controlled by the autonomic nervous system.
• Thought, speech, learning, voluntary muscle movements, and doing math calculus require higher-level cognitive processing.

Question 43

• The answer is A. The atmosphere
• Phosphorus cycle describes movement of phosphorus through the spheres of earth.
• Phosphorus is least abundant in atmosphere of all the other spheres.
• Phosphorus is mostly found in rocks and ocean sediments.

Question 44

• The answer is A. Stomach
• Steatorrhea is the presence of excess fat in feces, indicating fat malabsorption.
• The liver, small intestine, pancreas, and glands of the small intestine walls are all involved in fat digestion and absorption.
• The stomach primarily handles initial digestion and does not play a major role in fat absorption.

Question 45

• The answer is C. I and III
• Enzymes increase reaction rates by stabilizing the transition state
• Enzymes lower activation energy by altering the reaction pathway.
• Enzymes do not raise activation energy or shift the equilibrium; they only speed up the rate at which equilibrium is reached.

Question 46

• The answer is C. Metaphase
• Chromosomes are aligned at the metaphase plate (middle of the cell).
• This is a characteristic feature of metaphase in mitosis.

Question 47

• The answer is A. Most of the water on Earth is held in deep water bodies not easily affected by solar energy.
• The presence of water in nature is ensured by the water cycle.
• The water cycle takes time because a large portion of Earth's water is in deep water bodies, which are not easily affected by solar energy.

Question 48

• The answer is B. Autosomal-dominant
• The disease appears in every generation.
• Affected individuals have at least one affected parent.
• Males and females are equally affected.

Question 49

• The answer is E. 0%
• Person A is affected and has an autosomal dominant condition.
• The condition requires only one copy of the affected allele.
• The wild-type male does not have any affected allele.
• The offspring will inherit one allele from each parent.
• The offspring will have a 0% chance of inheriting the disease.

Question 50

• The answer is B. Frogs with the brown skin mutation are able to survive and reproduce more successfully than frogs without it.
• The key factor is the ability to survive and reproduce more successfully.
• This is the definition of natural selection.

Question 51

• The answer is B. X: maltose and Y: sucrose
• Maltose is a disaccharide composed of two glucose molecules, while sucrose is composed of glucose and fructose.
• Following cleavage, both would yield monosaccharides with aldehyde functionality.

Question 52

• The answer is B. Pulmonary arteries only
• Pulmonary arteries carry deoxygenated blood from the heart to the lungs to get oxygenated.
• Coronary arteries carry oxygenated blood to the heart muscle.
• Pulmonary veins carry oxygenated blood from the lungs back to the heart.
• Capillaries are involved in nutrient and waste exchange but do not carry blood away from the heart.

Question 53

• The answer is E. II and IV
• During prophase of mitosis, the nuclear membrane disappears, and the centrioles move to opposite poles, forming asters and spindle fibres.
• Chromosomes line up at the middle of the cell during metaphase.
• Cytoplasm divides during cytokinesis.

Question 54

• The answer is B. Artificial selection
• Artificial selection involves humans intentionally selecting for specific traits in organisms.
• Selective breeding for short snouts and flat faces caused the traits to appear.

Question 55

• The answer is D. Density
• Lipoproteins differ in density due to varying ratios of lipids and proteins.
• Density influences how they transport lipids in the bloodstream.

Question 56

• The answer is C. Blood temperature
• The renal system regulates blood pressure, solute concentrations, pH, and filtration.

Question 57

• The answer is D. Large molecular weight protein
• Glomerular filtrate contains water, electrolytes, amino acids, and glucose.
• Large proteins are typically retained in the blood due to their size.

Question 58

• The answer is B. Viviparity
• Viviparity (live birth) is shared by kangaroos and foxes.
• Platypuses lay eggs (not viviparous).
• Kangaroos have a pouch, but this isn't necessarily shared by foxes. Lactation is common to all mammals.
• Two post-orbital fenestrae is not in kangaroos.

Question 59

• The answer is A. Monkey
• The cladogram shows shared ancenstry.
• Monkey is closer to fox than the other species.

Question 60

• The answer is E. The active site can be influenced by molecules binding elsewhere on an enzyme.
• Regarding the induced fit model of enzyme catalysis, an enzyme changes shape upon substrate binding.
• This conformational change optimizes the interaction and can be influenced by molecules binding at sites other than the active site.

Question 61

• The answer is C. Met - Tyr - Gly - Phe - Ser - Stop
• Converting template DNA to mRNA sequence yields 5'-AUG CCG AAG UCU UGA-3'
• AUG is the start codon and codes for methionine.
• CCG codes for glycine, AAG codes for lysine, and UCU codes for serine. UGA is a stop codon.

Question 62

• The answer is D. Prophase I
• Crossing over occurs during prophase I of meiosis.
• Homologous chromosomes pair up, exchange genetic material, leading to genetic variation.

Question 63

• The answer is C. Secondary structure
• The alpha helix is a common secondary structure in proteins.
• It is formed by hydrogen bonds between amino acids in polypeptide chain.

Question 64

• The answer is A. 2
• In DNA, A pairs with T, and G pairs with C.
• If A is 20% and G is 30%, then T is also 20%, and C is also 30%.
• Given 20 total nucleotides, T = 20% of 10 = 4.
• But in reality A=T, so the math done earlier (T = 20% of 10 = 4) is wrong.
• Given 20 total nucleotides, the number of As= 20% of 20= 4, hence the number of Ts = 4 as well.
• Given 20 total nucleotides, the number of Gs= 30% of 20= 6, hence the number of Cs = 6 as well.
• Since %A + %T + %G + %C = 100%, this means %A + %T = 40%, therfore %G + %C = 60%
• The percentage does not add up to 100%, (20 + 30 + x +y = 100), assuming the number of G is correct.
• There has to be an error in the amount of Gs in the molecule therefore.
• Lets assume A=20%, and T=20%, therefore Gs = 30% and Cs = 30%, so this means 20+20+30+x = 100, so x =30%
• Now we can assume the number of T molecules is 20% of 20= 4, A=4, G =6, and C=6, giving us a total of 20 nucleic acids.

Question 65

• The answer is B. Paracrine function
• Paracrine signaling involves a cell releasing a signal that affects nearby cells.

Question 66

• The answer is D. Presence of the enzyme
• Factors that affect reaction rate include temperature, pH, substrate concentration.
• An enzyme acts as only a catalyst
• Removing the enzyme would stop the forward and backward reaction from occuring.

Question 67

• The answer is D. Glucagon
• After consuming a cheeseburger and milkshake, insulin, secretin, and cholecystokinin would be expected to increase
• Insulin increases due to increase in blood sugar level.
• Secretin and cholecystokinin increase in response to fat and protein digestion.
• Glucagon works to raise blood sugar levels and would not be expected to increase.

Question 68

• The answer is C. Type-AB, type-A, and type-B
• A person with type-B blood has either BB or BO alleles.
• A person with type-AB blood has AB alleles.
• Possible combinations: AB + BB -> AB or BB & AB + BO -> AA, BB, AB, BO.
• The possible blood types of their children are type-A, type-B, and type-AB.

Question 69

• The answer is A. Normal lysosomes contain different degradative enzymes that can hydrolyze lipids and prevent their accumulation.
• Wolman disease is characterized by a lysosomal enzyme deficiency, leading to the accumulation of lipids.

Question 70

• The answer is D. 6.25%
• Mother is a carrier so the genotype is XcX.
• Father is unaffected so the genotype is XY.
• The possibilities for children are: XX, XcX, XY, XcY.
• Male and colorblind genotype occurs 1/4 of the time.
• Thus the probability of the first child being affected and male is 1/4 * 1/2 =1/8. The probability of the second child being affected and male is 1/4 * 1/2 = 1/8.
• The probability of both children being colorblind and male is (1/4 * 1/2) * (1/4 * 1/2) = 1/64 = 0.015625= 1.5625%

Question 71

• The answer is A. Collecting ducts
• ADH (antidiuretic hormone) increases water reabsorption in the collecting ducts of the kidneys.

Question 72

• The answer is C. ATP production in the cell will decrease.
• Damage to the chloroplast membrane would affect all functions carried out in the mitochondria.
• Damage to the membrane affects ATP production.

Question 73

• The answer is B. The levels of T3 and T4 hormones are low, which indicates hypothyroidism.
• Hypothyroidism occurs when low T3 and low T4 levels are preesent.
• Sympoms include fatigue, weight gain, hair loss, muscle cramps, and depression.

Question 74

• The answer is E. Fascicle, muscle fiber, myofibril
• A muscle is composed of fascicles.
• Fascicles are composed of muscle fibers.
• Muscle fibers are composed of myofibrils.

Question 75

• The answer is D. Nondisjunction
• Nondisjunction is the failure of chromosomes to separate properly during cell division.
• Abnormality such as Trisomy 21 (Downs syndrome) is often a result of nondisjunction.

Question 76

• The answer is B. Most of the refraction of the incoming light rays occurs at the cornea.
• The cornea is responsible for most of the refraction (bending) of light as it enters the eye.

Question 77

• The answer is C. All their sons will be normal, and all their daughters will be carriers.
• Since the mom has normal vision and does not carry the allele for degenerative myopia, the mom has XX genotype,
• Since the man has an X-linked disease, his genotype is X'Y.
• All sons will receive an X chromosome from mom, with genotype X'Y = normal.
• All daughters will have carriers, with geotype XX'.

Question 78

• The answer is C. Feedback inhibition
• Feedback inhibition occurs when the product of a reaction binds to the enzyme.
• ATP produces G-6-P which blocks the acess to ATP.

Question 79

• The answer is D. To prevent the mixing of oxygenated and deoxygenated blood inside the heart
• Mammals and birds have separate chamber to ensure that oxygenated and deoxygenated blood does not mix.

Question 80

• The answer is E. 200
• Starch, each containing 100 monosaccharide subunits, are cleaved completely by specific enzymes.
• 2 polymers containing 100 subunits each will produce 200 molecules of glucose after a complete cleavage.