Congratulations - you have completed .
You scored %%SCORE%% out of %%TOTAL%%.
Your performance has been rated as %%RATING%%
Your answers are highlighted below.
Which of the following environmental conditions does not affect the activity of enzymes?
The amount of free energy in the cell
Chemicals in the enzyme’s environment
Question 1 Explanation:
The correct answer is (B). Typically, the rate of enzymatic reactions increases with temperature (up to a point), this is because increased temperature means increased energy means increased motion which makes for more frequent collisions of substrates with active sites. pH can have an impact on the functioning of an enzyme. For example, the stomach enzyme pepsin works best at a pH of about 1.5 and the enzyme trypsin, which acts in the small intestine, works best at a pH of about 8. Because enzymes are sensitive to their environment, certain chemicals can denature the protein, rendering it unable to perform its function. The amount of free energy in the cell does not affect the function of the enzyme.
Some enzymes require an effector in order to conform to a substrate. The site to which the effector binds is the:
Question 2 Explanation:
The correct answer is (C). The binding of an effector to the allosteric site will change the shape of the active site (the site to which the substrate binds) allowing (or preventing) the substrate to attach.
Why will the enzyme sucrase only act on sucrose and not bind to other disaccharides, such as maltose?
Because of sucrose’s molecular formula
Because sucrose has a 1-2 glycosidic linkage and maltose has a 1-4 glycosidic linkage
Because sucrose fits perfectly into sucrase’s active site, and other disaccharides do not
Because sucrose contains fructose
Question 3 Explanation:
The correct answer is (C). Enzymes work exclusively on specific substrates, based on their shape.
How do enzymes change the speed of chemical reactions in cells?
They increase the heat in the cell, and therefore speed up the reaction by allowing reactants to attain the transition state more often
Enzymes speed up reactions by changing the amount of free energy available in the cell for reactions
Enzymes make endergonic reactions exergonic
Enzymes speed up reactions by bringing substrates together to undergo a chemical reaction
Question 4 Explanation:
The correct answer is (D). Enzymes have a specialized area on the molecules called the active site, which bring substrates together for a chemical reaction to take place.
Which of the following is not an example of a catabolic pathway?
Citric Acid Cycle
Question 5 Explanation:
The correct answer is (D). Answers (A), (B) & (C) are catabolic because they result in the net release of energy with the end products being simpler than the input. Photosynthesis is an anabolic pathway since it results in the net gain of energy with the end products of the reaction being more complex than the input.
A battery being used in a flashlight is an example of:
Question 6 Explanation:
The correct answer is (C). Chemical energy is energy that is stored in chemicals. In the case of the battery, when the positive and negative terminals are connected so that electricity can flow between them, chemical reactions occur at the electrodes. The reactions release excess electrons at the anode which flow to the cathode.
Which statement is true of a cell in chemical equilibrium?
Cells in chemical equilibrium can no longer do work, and therefore, will die
Cells are most stable in chemical equilibrium, and able to produce molecules needed for biological processes to continue
Cells in chemical equilibrium are healthy and productive; cells in chemical disequilibrium typically are cancerous
As cells reach chemical equilibrium, the free energy of the mixture of reactants and products increases
Question 7 Explanation:
The correct answer is (A). If chemical reactions occurred in a test tube, they would eventually reach chemical equilibrium. Systems with chemical equilibrium have a minimum amount of free energy, and therefore they cannot do any work, and will eventually die. This is a very important aspect of life: that metabolism as a whole is never at equilibrium.
During the above reaction in glycolysis, which molecule acts as the oxidizing agent?
Question 8 Explanation:
The correct answer is (A). NAD+ is the oxidizing agent because it accepts electrons from glyceraldehyde-3-phosphate.
In the same reaction above in glycolysis, which molecule acts as the reducing agent?
Question 9 Explanation:
The correct answer is (C). Glyceraldehyde-3-phosphate is the reducing agent because it donates electrons to NAD+.
Which part of photosynthesis takes place in the stroma, uses ATP and NADPH to convert CO2 to the sugar G3P, and returns ADP and NADP+?
Electron Transport Chain
Question 10 Explanation:
The correct answer is (A). The Calvin Cycle can be broken down into 3 steps: (1) Carbon fixation, which incorporates each CO2 molecule by attaching it to a 5-carbon sugar (ribulose-1,5-bisphosphate), (2) Reduction, where each molecule of 3-phosphoglycerate receives an additional phosphate group from ATP and hydrogen from NADPH forming glyceraldehyde-3-phosphate, and (3) Regeneration of the CO2 acceptor (ribulose-1,5-bisphosphate). This all takes place in the stroma.
Which of the following reactions represents photosynthesis?
Pyruvate + NADH + H+ → Lactate + NAD2
C4H6O5 + NAD+ → C4H4O5 + NADH + H+
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
6CO2 + 6H2O + Energy → C6H12O6 + 6O2
Question 11 Explanation:
The correct answer is (D). The summary equation of photosynthesis is the reverse of that of cellular respiration. Carbon dioxide, plus water, plus energy in the form of light are converted to glucose and oxygen inside a chloroplast.
What color of light is least effective in driving photosynthesis?
Question 12 Explanation:
The correct answer is (C). Most plants appear to be green. This is because green light is reflected and not available to provide energy for photosynthesis.
Which type of plants has a unique leaf structure, specifically adapted to hot, dry climates which helps to maintain CO2 concentration in the bundle sheath that favors photosynthesis over photorespiration?
Question 13 Explanation:
The correct answer is (A). C4 plants are given such a name because they preface the Calvin Cycle with an alternate mode of carbon fixation that forms a 4-carbon compound as its first product.
Which of the following biological process is not a step in cellular respiration:
Citric Acid Cycle
Question 14 Explanation:
The correct answer is (D). The Calvin Cycle is a the process by which ATP and NADPH convert CO2 to sugar in photosynthesis.
During which phase of cellular respiration is the most ATP produced?
Conversion of pyruvate to acetyl CoA
Citric Acid Cycle
Question 15 Explanation:
The correct answer is (B). Oxidative phosphorylation uses energy released by the electron transport chain to power ATP synthesis.
Which metabolic pathway is used by cellular respiration and fermentation?
Citric Acid Cycle
Electron Transport Chain
Question 16 Explanation:
The correct answer is (A). Fermentation consists of glycolysis plus reactions that regenerate NAD+.
Insulin is secreted by the pancreas, and controls blood sugar levels. When blood sugar level rises, the body responds by secreting insulin into the blood to lower blood sugar levels. When the blood sugar level reaches homeostasis, the pancreas stops releasing insulin. This system is an example of:
Question 17 Explanation:
The correct answer is (B). Negative feedback is the most common type of regulation in which the accumulation of the end product slows the process of producing more.
If a mammal such as an elk migrates from sea level to an area of high altitude, changes occur to accommodate activity at lower oxygen concentrations. These changes include an increased production of red blood cells and an increase in blood flow to the lungs. These changes are an example of:
Question 18 Explanation:
The correct answer is (C). One way in which an animal adjusts to changes in their external environment within the normal range of homeostasis is known as acclimatization. Acclimatization is a temporary change.
Which type of heat exchange involves the direct transfer of heat between molecules of objects in direct contact with each other?
Question 19 Explanation:
The correct answer is (D). Conduction takes place when heat moves between two objects that are touching each other, such as a snake basking on a rock.
Which types of animals utilize the countercurrent exchange of heat as a means of maintaining homeostasis?
Question 20 Explanation:
The correct answer is (D). Countercurrent exchange reduces heat loss when arteries carrying warm blood down the legs of waterfowl are in close contact with veins returning cold blood from cold lakes or ponds. This allows the heat from the blood in the arteries to warm the cold blood returning in the veins. When the blood from the veins reaches the body core, it is almost as warm as the body.
Which types of animals would most likely include osmoconformers?
Question 21 Explanation:
The correct answer is (A). The osmolarity of the body fluids of sea stars (starfish) conforms to that of marine waters in which they are found.
How does physical or emotional stress affect blood pressure?
Smooth muscles relax
Blood pressure decreases
Arterioles narrow, increasing blood pressure upstream in the arteries
Arterioles increase in diameter
Question 22 Explanation:
The correct answer is (C). When there is physical or emotional stress, nervous and hormonal responses trigger smooth muscles in arteriole walls to contract. This causes the arterioles to narrow, increasing blood pressure in the upstream arteries.
When a young seed is germinating, what environmental cue does it use to grow its leaves upward and roots downward when sunlight is not available (as in, when it is buried in the soil)?
Question 23 Explanation:
The correct answer is (C). Gravity provides the environmental cue signaling for the roots display positive gravitropism (growing downward) and the shoots to display negative gravitropism (growing upward). Photomorphogenesis describes the effects of sunlight on plant growth. Photoperiodism is the physiological response to a photoperiod (relative lengths of day and night), such as long-day and short-day plants. Thigmotropism is directional growth in response to touch, such as a vine wrapping its tendrils around another plant’s stem.
Once you are finished, click the button below. Any items you have not completed will be marked incorrect.
There are 23 questions to complete.