Chapter 2: Movement of substances

Question 1

What is active transport?

Answer 1

Active transport is the net movement of substances against a concentration gradient, with the use of energy that is released from respiration (takes place through a partially permeable membrane)

Question 2

What is diffusion?

Answer 2

Diffusion is the net movement of substances down a concentration gradient, with or without a partially permeable membrane without the use of energy.

Question 3

What is osmosis?

Answer 3

Osmosis is the net movement of water molecules down a water potential gradient through a partially permeable membrane without the use of energy

Question 4

Why is turgor pressure so important to plants (Think about its shape and support)

Answer 4

1. It helps to maintain the shape of soft tissues in plants.
2. Helps to provide mechanical support to the plants so they can be upright to get maximum sunlight for photosynthesis.
3. Provides mechanical support for the cell membrane and prevents it from bursting when the cell is filled with water

Question 5

How does volume to surface area ratio of a root hair cell (for instance) affect its function?

Answer 5

An increased SA:V ratio would allow for a increase rate of absorption of mineral salts via active transport

Question 6

Describe the state of a RBC when placed in a hypotonic solution

Answer 6

1. The RBC increases in size and swells and potentially bursts
2. Water molecules move from the hypotonic solution to the red blood cell down a water potential gradient.
3. Water enters the red blood cell via osmosis and thus expands and bursts.

Question 7

What are the keywords to describe a plant tissue and cell placed in a hypertonic solution respectively?

Same question but placed in a hypotonic solution

Answer 7

Plant tissue: Flaccid
Plant cell: plasmolyzed

Hypotonic
Plant tissue: Firm
Plant cell: Turgid

Question 8

What are the keywords to describe an animal cell and tissue placed in a hypertonic solution and hypotonic solution respectively.

Answer 8

Hypertonic
animal tissue: Flaccid
animal cell: Crenated

Hypotonic
Animal cell: Burst

Question 9

What is plasmolysis?

Answer 9

It is when the cell membrane and cytoplasm shrink away from the cell wall.

Question 10

Why doesn’t a plant cell burst when placed in a solution of higher water potential?

Answer 10

As water enters the cell, the vacuole increases in size and pushes the cytoplasm against the cell wall. However, the cell wall provides structural support for the cell membrane, preventing it from bursting when water enters the cell.