Movement Into and Out of Cells

Question 1

What is diffusion?

Answer 1

Diffusion is the net movement of particles from an area of high concentration to an area of low concentration down the concentration gradient, due to their random movement.

Question 2

What provides energy for diffusion?

Answer 2

The kinetic energy of the molecules and ions provides energy for diffusion.

Question 3

Why is diffusion important for cells?

Answer 3

Diffusion allows crucial substances like oxygen and glucose to enter cells for metabolic processes like respiration and photosynthesis.

Question 4

What factors affect the rate of diffusion?

Answer 4

Surface area: Greater surface area increases the rate.
Temperature: Higher temperatures increase the rate by providing more kinetic energy.
Concentration gradient: A steeper gradient increases the rate.
Diffusion distance: Shorter distances increase the rate.

Question 5

What is osmosis?

Answer 5

Osmosis is the net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane.

Question 6

What happens to plant cells during osmosis?

Answer 6

Turgid: Water enters, and the cell swells due to turgor pressure.
Flaccid: Water leaves, and the cell shrinks slightly.
Plasmolysis: Excessive water loss causes the cell membrane to peel away from the cell wall.

Question 7

What happens to animal cells during osmosis?

Answer 7

In a hypotonic solution (high water potential), cells may burst (lysis).

In a hypertonic solution (low water potential), cells shrink.

Question 8

How can osmosis be demonstrated using dialysis tubing?

Answer 8

Fill dialysis tubing with concentrated sucrose solution and immerse it in distilled water. Water will move into the tubing (lower water potential) via osmosis.

Question 9

What is active transport?

Answer 9

Active transport is the movement of molecules against a concentration gradient (low to high concentration) using energy from respiration.

Question 10

What role do carrier proteins play in active transport?

Answer 10

Carrier proteins in the cell membrane bind molecules on the side with lower concentration, use energy to change shape, and transport them to the side with higher concentration.

Question 11

Give examples of active transport.

Answer 11

Uptake of ions like nitrates by root hair cells.

Uptake of glucose in the small intestine and kidney tubules.

Question 12

Why is water essential in cells?

Answer 12

Maintains turgor pressure for support.

Acts as a solvent for metabolic reactions.

Buffers temperature due to high specific heat capacity.

Question 13

How do root hair cells take up water?

Answer 13

By osmosis, as water moves from the soil (high water potential) into root hair cells (low water potential).

Question 14

What are the conditions of cells in different osmotic environments?

Answer 14

Environment Plant Cell Animal Cell
Hypotonic (dilute) Turgid Swells, may burst
Isotonic (same) No change No change
Hypertonic (concentrated) Plasmolysis Shrinks

Question 15

What is turgor pressure?

Answer 15

Turgor pressure is the pressure exerted by the cell membrane pushing against the cell wall when a plant cell becomes turgid due to water entering via osmosis.

Question 16

What does it mean for a plant cell to be flaccid?

Answer 16

A flaccid plant cell has lost water via osmosis, causing it to shrink slightly, though the cell membrane remains attached to the cell wall.

Question 17

What is plasmolysis?

Answer 17

Plasmolysis occurs when a plant cell loses too much water, causing the cell membrane to peel away from the cell wall.

Question 18

What is dialysis tubing, and how is it used to study osmosis?

Answer 18

Dialysis tubing is a partially permeable membrane made of cellulose. It allows small molecules like water to pass through while blocking larger molecules like sucrose. It is used to demonstrate osmosis by placing it in solutions with different water potentials.

Question 19

Why is active transport important in plants?

Answer 19

Active transport is crucial for the uptake of ions like nitrates and magnesium from the soil, which are essential for plant growth and metabolism.

Question 20

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

Answer 20

Water enters the cell by osmosis, causing it to swell and potentially burst (lysis) due to the lack of a cell wall.

Question 21

Why do plant cells not burst in a hypotonic solution?

Answer 21

Plant cells have a rigid cell wall that prevents them from bursting when they become turgid in a hypotonic solution.

Question 22

How does temperature affect the rate of diffusion?

Answer 22

Higher temperatures increase the kinetic energy of molecules, causing them to move faster and increasing the rate of diffusion.

Question 23

How does surface area affect diffusion?

Answer 23

An increase in surface area provides more space for particles to move through, enhancing the rate of diffusion.

Question 24

What is the difference between osmosis and diffusion?

Answer 24

Osmosis: Movement of water across a partially permeable membrane from high to low water potential.

Diffusion: Movement of particles from high to low concentration.

Question 25

How does active transport differ from diffusion and osmosis?

Answer 25

Active transport requires energy from respiration to move molecules against their concentration gradient, whereas diffusion and osmosis are passive processes.

Question 26

What role does water play in metabolic reactions?

Answer 26

Water acts as a medium for metabolic reactions and helps maintain the optimum temperature for enzyme activity due to its high specific heat capacity.

Question 27

Why is osmosis important for water regulation in plants?

Answer 27

Osmosis ensures water moves from the soil into root hair cells, maintaining hydration necessary for photosynthesis and structural support.

Question 28

What is the water potential gradient?

Answer 28

The water potential gradient is the difference in water potential between two areas, driving the movement of water during osmosis.

Question 29

Why is energy required for active transport?

Answer 29

Energy from respiration is needed to move molecules against their concentration gradient, which does not happen naturally.

Question 30

How does active transport occur in root hair cells?

Answer 30

Root hair cells use energy to actively transport ions like nitrates from the soil (low concentration) into the cell (high concentration).

Question 31

What are carrier proteins, and how do they function?

Answer 31

Carrier proteins are embedded in the cell membrane and help transport molecules by changing shape using energy, moving the molecules to the opposite side of the membrane.

Question 32

What is isotonic, and what happens to cells in isotonic solutions?

Answer 32

Isotonic solutions have equal solute concentrations inside and outside the cell, so there is no net movement of water, and cells remain unchanged.

Question 33

What is the relationship between diffusion distance and the rate of diffusion?

Answer 33

A shorter diffusion distance increases the rate of diffusion as particles have less distance to travel.

Question 34

How does water potential affect osmosis?

Answer 34

Water moves from a region of higher water potential (less concentrated solution) to a region of lower water potential (more concentrated solution) through osmosis.

Question 35

Why do cells in the kidney tubules perform active transport?

Answer 35

Cells in kidney tubules actively transport glucose and other essential molecules back into the blood against the concentration gradient.

Question 36

How can the factors influencing diffusion be investigated?

Answer 36

The factors can be investigated by varying surface area, temperature, concentration gradient, and distance in controlled experiments to observe their effects on diffusion rates.

Question 37

How does water move in and out of cells?

Answer 37

Water moves in and out of cells through the cell membrane by osmosis.

Question 38

What happens to plant tissues in solutions of different concentrations?

Answer 38

In a dilute solution: Water enters cells, making them turgid.

In a concentrated solution: Water leaves cells, making them flaccid or plasmolyzed.

Question 39

What are the terms used to explain osmosis in plant cells?

Answer 39

Turgid: Swollen cells due to water uptake.
Turgor pressure: Pressure exerted by the cell membrane against the cell wall.
Flaccid: Cells lose water and become soft.
Plasmolysis: The cell membrane peels away from the cell wall when water loss is severe.

Question 40

Why is water potential important for organisms?

Answer 40

Water potential determines the movement of water by osmosis, essential for processes like nutrient transport and maintaining cell structure.

Question 41

Why is active transport important?

Answer 41

Active transport allows cells to take up nutrients and ions even when they are in lower concentrations outside the cell, such as:

Ion uptake by root hairs for plant growth.
Glucose absorption in the small intestine.

Question 42

How does active transport occur?

Answer 42

Carrier proteins in the cell membrane use energy from respiration to transport specific molecules or ions across the membrane against the concentration gradient.

Question 43

What is an example of active transport in plants?

Answer 43

Uptake of nitrate ions by root hair cells, where ion concentrations in the soil are lower than inside the root hair cells.

Question 44

What is an example of active transport in animals?

Answer 44

Glucose absorption in the small intestine, where glucose moves against its concentration gradient into the bloodstream.