Biology Chapter 3.5 Active Transport Quiz

Questions and Answers

Describe active transport.

Active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration; uses transport proteins powered by chemical energy; cells use active transport to get needed molecules regardless of the concentration gradient and to maintain homeostasis.

What do protein pumps do?

Protein pumps move contents from lower concentrations to higher concentrations.

Why do cells use active transport?

Cells use active transport to get needed molecules regardless of the concentration gradient and to maintain homeostasis.

How does active transport move molecules against the concentration gradient?

Active transport proteins can use chemical energy to move a substance against its concentration gradient. Signup and view all the answers

Describe the sodium-potassium pump.

The sodium-potassium pump uses energy directly from the breakdown of ATP. It pumps three sodium ions out of the cell for every two potassium ions it pumps in. Signup and view all the answers

Describe the proton pump.

The proton pump uses energy from the breakdown of ATP to move hydrogen ions (or protons) out of the cell, creating a concentration gradient. Signup and view all the answers

How do cells move large molecules in and out of the cell?

Transport in vesicles lets substances enter or exit a cell without crossing through the membrane. Signup and view all the answers

Describe endocytosis.

Endocytosis is the process of taking liquids or fairly large molecules into a cell by engulfing them in a membrane. Signup and view all the answers

What is phagocytosis?

Phagocytosis is a type of endocytosis in which the cell membrane engulfs large particles. Signup and view all the answers

What does phagocytosis do for the immune system?

Macrophages help your body fight infection by finding and engulfing foreign materials such as bacteria and destroying them. Signup and view all the answers

Describe exocytosis.

Exocytosis is a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane. Signup and view all the answers

What does exocytosis do in the human body?

Exocytosis releases chemical signals at nerve endings, helping transmit messages throughout the nervous system. Signup and view all the answers

What might happen if your vesicles in your neurons were suddenly unable to fuse with the cell membrane?

The vesicle wouldn't be able to expel its contents, resulting in some nerve functions being severed. Signup and view all the answers

Under what conditions would a molecule need to be actively transported across a membrane?

Active transport is needed when moving against the concentration gradient, such as when glucose is taken in. Signup and view all the answers

How do transport proteins that are pumps differ from those that are channels?

Pumps require energy to move substances in a specific direction, while channels allow molecules to pass through passively. Signup and view all the answers

How do endocytosis and exocytosis differ from diffusion?

Endocytosis and exocytosis involve moving substances in and out of the cell using energy, while diffusion is a passive process. Signup and view all the answers

Small lipid molecules are in high concentration outside a cell. They slowly cross the membrane into the cell. What term describes this action? Does it require energy?

Diffusion is the movement of a molecule from high concentration to low concentration; it takes no energy. Signup and view all the answers

Ions are low in concentration outside a cell. They move rapidly into the cell via protein molecules. What term describes this action? Does it require energy?

Active transport drives molecules across a membrane from a region of lower concentration to higher concentration; it uses energy. Signup and view all the answers

Do you think endocytosis and exocytosis can occur within the same cell?

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Study Notes

Active Transport Overview

Active transport moves molecules from lower to higher concentrations, requiring energy.
Utilizes transport proteins powered by chemical energy to maintain cellular homeostasis.

Protein Pumps

Protein pumps shift ions or molecules from regions of lower to higher concentrations using energy.

Purpose of Active Transport

Essential for cells to acquire necessary substances regardless of existing concentration gradients.

Mechanism Against Concentration Gradient

Active transport proteins harness chemical energy (ATP) to relocate substances against their gradients.

Sodium-Potassium Pump

Transports three sodium ions out for every two potassium ions in, using ATP energy for function.

Proton Pump

Utilizes ATP to move hydrogen ions (H+) out of the cell, creating a positive charge outside the cell compared to inside.

Vesicular Transport

Large molecules enter or exit cells without crossing the membrane via transport in vesicles.

Endocytosis

Engulfs large molecules or liquids by forming a pocket in the membrane that transforms into a vesicle within the cell.

Phagocytosis

A specific type of endocytosis where the cell membrane engulfs large particles, effectively admitting them into the cell.

Phagocytosis in Immunity

Macrophages engulf and destroy foreign substances, such as bacteria, aiding in immune response.

Exocytosis

The release of cell vacuole contents to the exterior, achieved through the fusion of vacuole and cell membranes.

Role of Exocytosis in the Human Body

Essential for neurotransmission; vesicles at nerve endings release chemicals, converting electrical signals to chemical signals between neurons.

Impact of Vesicle Fusion Failure

If vesicles in neurons cannot fuse with membranes, it disrupts the release of neurotransmitters, impairing nerve function.

Conditions for Active Transport

Active transport is required when moving molecules against the concentration gradient, typically using ATP to facilitate transport.

Difference between Transport Proteins

Pump proteins require energy for movement and function actively, while channel proteins facilitate passive transport when opened.

Endocytosis and Exocytosis vs. Diffusion

Endocytosis and exocytosis are energy-requiring processes for moving substances into or out of the cell versus diffusion, which occurs naturally down a concentration gradient.

Diffusion of Small Lipid Molecules

Movement of small lipid molecules from high to low concentration across the membrane is termed diffusion and does not require energy.

Active Transport of Ions

Ions moving rapidly into the cell from lower to higher concentration via protein molecules is an example of active transport, which requires energy.

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Description

Test your knowledge of active transport mechanisms in biology. This quiz covers key concepts including the role of protein pumps and concentration gradients. Perfect for students studying cell biology and membrane functions.