Unit 3 - Movement into & out of the cells

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What does diffusion involve in biological systems?

Random movement of molecules against a concentration gradient
Movement of molecules from higher to lower concentration (correct)
Movement of molecules from lower to higher concentration
Selective absorption of molecules by the cell membrane

What role does the cell membrane play in diffusion?

It is completely impermeable to all substances
It regulates movement only based on electrical charges
It facilitates the movement of all molecules without restriction
It selectively allows certain molecules to pass through (correct)

Which of the following examples illustrates diffusion in living organisms?

Water diffusing into cells against the gradient
Cell waste expelled through vesicular transport
Nutrients actively transported into cells
Oxygen moving from lungs to bloodstream (correct)

In the context of plants, when do they require carbon dioxide for photosynthesis?

When light and temperature conditions are optimal (B) Signup and view all the answers

Which substances are typically obtained by diffusion in the small intestine?

Digested food products like glucose and amino acids (B) Signup and view all the answers

What causes plant cells to become turgid?

Increase in turgor pressure from water uptake (D) Signup and view all the answers

What happens to animal cells placed in a strong sugar solution?

They become crenated (C) Signup and view all the answers

Which of the following describes active transport?

Movement of particles against a concentration gradient using energy (B) Signup and view all the answers

What is the consequence of plant cells becoming flaccid?

Reduced ability to support the plant (C) Signup and view all the answers

What role do carrier proteins play in active transport?

They pick up specific molecules and move them against a concentration gradient (A) Signup and view all the answers

Which process is responsible for water moving out of plant cells when placed in a concentrated solution?

Osmosis (B) Signup and view all the answers

Why do animal cells not have the same ability to support themselves as plant cells?

They do not have cell walls (D) Signup and view all the answers

What is a possible effect of placing an animal cell in distilled water?

It will burst due to excessive water intake (A) Signup and view all the answers

What is the primary energy source that drives diffusion?

Kinetic energy from particle movement (B) Signup and view all the answers

What effect does an increased surface area to volume ratio have on diffusion rates?

Speeds up diffusion (C) Signup and view all the answers

How does temperature influence the rate of diffusion?

Higher temperatures increase molecular movement and diffusion (B) Signup and view all the answers

What occurs when plant tissue is placed in a concentrated salt solution?

Water leaves the plant tissue, causing it to lose mass (B) Signup and view all the answers

Why is water considered an essential solvent for living organisms?

It helps transport dissolved substances easily (D) Signup and view all the answers

Osmosis involves the movement of water from a region of _ water potential to a region of _ water potential.

Higher; lower (B) Signup and view all the answers

What is a likely outcome if a plant cell experiences excessive water intake by osmosis?

The cell will burst due to high pressure (C) Signup and view all the answers

Which of the following factors does NOT influence the rate of diffusion?

Light intensity (D) Signup and view all the answers

In an osmosis experiment, what would be indicated if plant tissue shows no change in mass after being placed in a solution?

There was a balance of water potential inside and outside (A) Signup and view all the answers

What is the role of cell membranes in osmosis?

They are selectively permeable to small molecules like water (C) Signup and view all the answers

What happens to plant cells when placed in distilled water?

They become turgid and firm (D) Signup and view all the answers

Which type of cell structure is specifically adapted to increase diffusion efficiency in animals?

Cells lining the ileum (C) Signup and view all the answers

What is the reason for using dialysis tubing in osmosis experiments?

To allow only specific small molecules to pass through (D) Signup and view all the answers

Which of the following accurately describes the movement of molecules across membranes?

Molecules move from areas of high concentration to low concentration (D) Signup and view all the answers

Diffusion

The movement of molecules from an area of high concentration to an area of low concentration.

Concentration Gradient

The difference in concentration of a substance between two areas.

Partially Permeable Membrane

A membrane that allows some substances to pass through easily, but restricts the passage of others.

How Diffusion Helps Living Organisms

The process by which cells obtain necessary substances, like nutrients, and eliminate waste products.