[SEC 3] CHAPTER 2 - movement of substances

Question 1

What is diffusion?

Answer 1

The net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient

Concentration gradient is the difference in concentration between two regions.

Question 2

What is a concentration gradient?

Answer 2

The difference in concentration between two regions

It is the driving force for the process of diffusion.

Question 3

What is dynamic equilibrium in the context of diffusion?

Answer 3

A state where the concentration on both sides is equal, and diffusion stops

At this point, there is no net movement of particles in either direction.

Question 4

What factor affects the rate of diffusion related to the size of molecules?

Answer 4

Smaller molecules diffuse faster

The size of molecules directly influences their ability to move through a medium.

Question 5

How does temperature affect the rate of diffusion?

Answer 5

Higher temperature results in faster diffusion

Higher temperatures increase the kinetic energy of molecules, enhancing their movement.

Question 6

What is the effect of concentration gradient on diffusion?

Answer 6

Steeper concentration gradient leads to faster diffusion

A greater difference in concentration between two areas accelerates the movement of molecules.

Question 7

How does the thickness of a membrane influence diffusion?

Answer 7

Thinner membrane allows for faster diffusion

A shorter distance for molecules to travel increases the rate of diffusion.

Question 8

What is the relationship between surface area to volume ratio and diffusion rate?

Answer 8

Larger surface area to volume ratio results in faster diffusion

A greater surface area provides more space for molecules to pass through.

Question 9

What is one application of diffusion in humans related to gas exchange?

Answer 9

Gaseous exchange at alveoli of lungs

Oxygen moves from the alveoli to the blood due to a concentration gradient.

Question 10

How do glucose and amino acids move from the small intestine to the blood?

Answer 10

They diffuse from the lumen of the small intestine to the blood in capillaries

The lower concentration of these substances in the blood facilitates this diffusion.

Question 11

What is the process of gaseous exchange at the stomata of plants?

Answer 11

Carbon dioxide moves into the leaf through tiny openings (stomata) due to lower concentration inside the leaf compared to the atmosphere.

Carbon dioxide is constantly being used up in the leaf.

Question 12

How do root hair cells absorb mineral salts?

Answer 12

Mineral salts are absorbed through diffusion and active transport from a higher concentration in the soil solution to a lower concentration in the cell sap of the root hair cells.

Mineral salts diffuse into the cell sap of root hair cells.

Question 13

Define osmosis.

Answer 13

The net movement of water molecules from a solution of higher water potential to a solution of lower water potential through a partially permeable membrane.

Osmosis is crucial for maintaining cell turgidity.

Question 14

What does water potential measure?

Answer 14

The tendency for water to move from one place to another.

It influences the direction of water movement in plants.

Question 15

What is a hypertonic solution?

Answer 15

A concentrated solution with lower water potential compared to another solution.

Cells in a hypertonic solution may lose water.

Question 16

What is an isotonic solution?

Answer 16

A solution having the same concentration (same water potential) as another solution.

No net movement of water occurs between isotonic solutions.

Question 17

What is a hypotonic solution?

Answer 17

A dilute solution with a higher water potential compared to another solution.

Cells in a hypotonic solution may gain water and swell.

Question 18

What happens to a plant when placed in a concentrated sucrose solution?

Answer 18

Water moves out of the cell sap by osmosis across the partially permeable membrane

This results in a higher water potential in the cell sap compared to the concentrated sucrose solution.

Question 19

What occurs to a cell when it becomes flaccid?

Answer 19

Plasmolysis occurs

This means the cell membrane and cytoplasm shrink away from the cell wall.

Question 20

What is the effect of a concentrated sucrose solution on the cell sap?

Answer 20

Cell sap in the concentrated solution becomes flaccid

This is observed in hypertonic solutions.

Question 21

What is turgor pressure?

Answer 21

The pressure exerted by the water on the cell wall

It occurs when water enters a plant cell, causing the vacuole to increase in size.

Question 22

What happens when a cell is placed in a hypotonic solution?

Answer 22

The cell becomes turgid

This occurs when water enters the cell, increasing the vacuole size and pushing contents against the cell wall.

Question 23

What is turgidity of the cell with water called?

Answer 23

Turgor

This refers to the state of being turgid due to water pressure.

Question 24

Fill in the blank: In a very concentrated solution, the cell is _______.

Answer 24

plasmolysed

This is a result of water leaving the cell.

Question 25

What happens to the cell wall when the vacuole increases in size?

Answer 25

It pushes the cell contents against the cellulose cell wall ## Footnote This is part of the process that creates turgor pressure.

Question 26

True or False: In an isotonic solution, a plant cell remains flaccid.

Answer 26

False ## Footnote An isotonic solution would not cause the cell to be flaccid; it remains in equilibrium.

Question 27

What is the relationship between turgor pressure and the cellulose cell wall?

Answer 27

The cellulose cell wall exerts an opposing pressure ## Footnote This helps maintain the shape and integrity of the plant cell.

Question 28

What is the definition of active transport?

Answer 28

The process where energy is required to move particles through a membrane against its concentration gradient ## Footnote Active transport moves particles from a region of lower concentration to a region of higher concentration.

Question 29

What type of energy source is required for active transport?

Answer 29

Energy from aerobic respiration ## Footnote Mitochondria carry out aerobic respiration, which is essential for active transport.

Question 30

When can active transport not occur?

Answer 30

When oxygen is absent ## Footnote The absence of oxygen prevents aerobic respiration, which is necessary for active transport.

Question 31

Give an example of a cell type that uses active transport.

Answer 31

Root hair cells ## Footnote Root hair cells absorb mineral salts (ions) mainly by active transport.

Question 32

What is required in large amounts for the process of active transport?

Answer 32

Many mitochondria ## Footnote A high number of mitochondria is necessary to provide the energy for active transport.

Question 33

How does the surface area to volume ratio affect active transport in large organisms?

Answer 33

A surface area : volume ratio is smaller ## Footnote In large organisms, the smaller surface area to volume ratio leads to slower rates of diffusion per unit mass.

Question 34

Why do active cells have a big surface area to volume ratio?

Answer 34

To ensure fast uptake of oxygen and nutrients and fast removal of waste ## Footnote A large surface area to volume ratio facilitates efficient transport processes.