Bio 121 Exam 2 Flashcards

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Questions and Answers

Which of the following statements about diffusion is true? (Select all that apply)

It requires expenditure of energy by the cell.

It is a passive process. (correct)

It always requires integral proteins of the cell membrane.

It occurs when molecules move from a region of lower concentration to a region of higher concentration.

It is very rapid over long distances.

Which of the following is a correct difference between active transport and facilitated diffusion?

Facilitated diffusion can move solutes against a concentration gradient, and active transport cannot.

Active transport can move solutes in either direction across a membrane, but facilitated diffusion can only move in one direction.

Active transport involves transport proteins, and facilitated diffusion does not.

Active transport requires energy from ATP, and facilitated diffusion does not. (correct)

Facilitated diffusion involves transport proteins, and active transport does not.

Which of the following statements about the sodium-potassium pump is correct?

The sodium-potassium pump uses an existing proton gradient to drive the movement of sodium and potassium ions.

The sodium-potassium pump transports Na+ and K+ across the plasma membrane in the same direction at the expense of ATP hydrolysis.

The sodium-potassium pump moves sodium out of the cell and co-transports protons into the cell.

The sodium-potassium pump is a symporter that results in a net negative charge outside the cell.

The sodium-potassium pump is an antiporter that results in a net negative charge inside the cell. (correct)

Which of the following statements about cotransport of solutes across a membrane is correct?

Cotransport proteins allow a single ATP-powered pump to drive the active transport of many different solutes. Signup and view all the answers

Which of the following enables a cell to pick up and concentrate a specific kind of molecule?

Receptor-mediated endocytosis. Signup and view all the answers

Which of the following categories best describes the function of the rough endoplasmic reticulum?

Protein production. Signup and view all the answers

Which of the following five membranes is the most likely to have a lipid composition that is distinct from the other four?

Mitochondrial outer membrane. Signup and view all the answers

Which of the following structures is found in animal cells but NOT plant cells?

Centrioles. Signup and view all the answers

At body temperature (37 °C), a very fluid plasma membrane would be composed of primarily?

Phospholipids with unsaturated hydrocarbon tails. Signup and view all the answers

Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the membrane would carbohydrates most likely be found?

On the outside (external) surface of the membrane. Signup and view all the answers

Which of the following best describes substrate-level phosphorylation?

An enzymatic process that transfers phosphate from a molecule to ADP. Signup and view all the answers

Which of the following best describes glycolysis?

A multistep metabolic process involving multiple enzymes. Signup and view all the answers

What best describes oxidation?

The loss of electrons from a molecule. Signup and view all the answers

Which of the following is true?

Pyruvate has more free energy than carbon dioxide. Signup and view all the answers

Which of the following must be true of the metabolism of sugar and oxygen into carbon dioxide and water, according to the laws of thermodynamics?

Energy is transferred, but some of it is dissipated as heat. Signup and view all the answers

Which of the following is true of glycolysis and the citric acid cycle (oxidative respiration)?

An end product of glycolysis is a molecule that can be further metabolized in the citric acid cycle. Signup and view all the answers

Where are the proteins of the electron transport chain located?

Mitochondrial inner membrane. Signup and view all the answers

Which of the following best describes the thermodynamic change when sugar and oxygen are reacted to produce carbon dioxide and water?

There is a decrease of free energy. Signup and view all the answers

Which molecule collects high energy electrons from glucose and transports them around the mitochondria so that they can eventually be given to oxygen?

NAD+/NADH. Signup and view all the answers

Chemiosmosis uses the energy from the sodium gradient across the mitochondrial membrane to synthesize ATP from ADP and inorganic phosphate.

False Signup and view all the answers

What step in photosynthesis produces oxygen?

The splitting of water. Signup and view all the answers

What molecule in the plant leaf is responsible for absorbing light for photosynthesis?

Chlorophyll. Signup and view all the answers

How do chloroplasts generate ATP for use in photosynthesis?

The electron transport chain and chemiosmosis. Signup and view all the answers

Which step in photosynthesis uses ATP?

The Calvin Cycle. Signup and view all the answers

Where does light absorption occur in a chloroplast?

The thylakoid membrane. Signup and view all the answers

Study Notes

Diffusion and Membrane Transport

Diffusion is a passive process that does not require energy, allowing molecules to move from areas of high concentration to low concentration.
Active transport uses ATP to move molecules against their concentration gradient, whereas facilitated diffusion does not require energy and allows movement with the gradient.
The sodium-potassium pump actively transports 3 sodium ions out and 2 potassium ions into the cell, creating a net negative charge inside.

Cotransport and Endocytosis

Cotransport proteins enable multiple solute transports using a pre-established gradient created by ATP-powered pumps.
Receptor-mediated endocytosis is a process allowing cells to selectively acquire bulk substances through specific receptors on their surface.

Organelles and Membrane Composition

Rough endoplasmic reticulum is studded with ribosomes to produce proteins that enter the ER lumen or integrate into the membrane.
Mitochondrial membranes differ in lipid composition due to mitochondrial replication rather than lipid transfer from the ER, unlike most other organelles.
Centrioles are present in animal cells but absent in plant cells, despite their organized microtubule systems.

Membrane Fluidity and Structure

At body temperature, fluid plasma membranes are primarily composed of phospholipids with unsaturated hydrocarbon tails, enhancing fluidity.
In the fluid mosaic model, carbohydrates attached to proteins face outward, forming part of the extracellular matrix.

Metabolic Processes

Substrate-level phosphorylation is the enzymatic transfer of a phosphate group to ADP, directly generating ATP.
Glycolysis is a multistep metabolic process transforming glucose, occurring in the cytosol and not directly involving oxidative reactions.

Electron Transport and Energy Transfer

Oxidation is characterized by the loss of electrons, while reduction is their gain; cellular respiration reactions are essential for energy extraction.
Glycolysis produces intermediate molecules that are substrates for the citric acid cycle, facilitating further energy production.

Mitochondrial Functions

Proteins of the electron transport chain are embedded in the mitochondrial inner membrane, crucial for ATP synthesis during oxidative phosphorylation.
The proton gradient, not sodium, drives ATP synthesis in chemiosmosis during electron transport.

Photosynthesis Mechanisms

The splitting of water during photosynthesis produces oxygen, while chlorophyll is the pigment responsible for light absorption.
ATP generation in chloroplasts primarily occurs via the electron transport chain and chemiosmosis during the light-dependent reactions, with the Calvin cycle utilizing ATP for glucose synthesis.

Light Reactions and the Calvin Cycle

The Calvin cycle uses ATP produced in light reactions to convert glyceraldehyde-3-phosphate into glucose, reinforcing the cyclic nature of photosynthesis.
Light absorption occurs in the thylakoid membrane of chloroplasts, facilitating the synthesis of ATP and NADPH during the light-dependent phase.

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Description

Test your knowledge on diffusion and its principles in this Bio 121 Exam 2 quiz. Learn about the key concepts that define diffusion and its role in cellular processes. Perfect for students looking to reinforce their understanding of biological processes.