Question

biology exam

1. which of the following phrases best describes active transport?

a. movement of substance against concentration gradient.
b. it does not use chemical energy.
c. formation of a vesicle around a large particle.
d. the reliance on diffusion of materials.

1. which phrase best describes the process of facilitated diffusion?

a. the movement of ions only.
b. the requirement of atp.
c. the movement of only nonpolar molecules.
d. there is no requirement of energy from the cell.

1. which of the following statements best describes osmosis?

a. the movement of proteins from inside the cell to outside the cell.
b. the movement of water molecules from an area of high concentration to an area of low concentration.
c. the movement of water molecules from an area of low concentration to an area of high concentration.
d. the movement of concentration gradients across a semipermeable membrane.

1. in an isotonic solution...

a. water enters the cell, causing the cell to swell and burst.
b. water exits the cell, causing the cell to shrivel up and die.
c. water does not enter or exit the cell, leaving the cell to remain as is.
d. water enters and exits the cell, causing the cell to remain stable.
in the beaker below, a cell is placed in a solution. the cell is represented by the circle.
use this beaker to answer questions 5 - 7.

1. determine the water concentration inside / outside of the cell.

a. 35% / 20% c. 85% / 90%
b. 50% / 75% d. 65% / 80%

1. what is the direction of osmosis?

a. the direction of osmosis is entering the cell.
b. the direction of osmosis is exiting the cell.
c. the direction of osmosis is entering & exiting the cell.
d. osmosis is not occurring in this cell.

1. what type of solution was the cell placed in?

a. hypertonic solution
b. hypotonic solution
c. isotonic solution
d. osmosis is not occurring in this cell.

Explanation:

1. Active transport moves substances against the concentration gradient and uses energy (ATP). Option a is incorrect as it says no chemical energy. Option b describes endocytosis. Option d is about passive transport. So, movement against concentration gradient (option a's first part is wrong, but among options, a's first part is wrong, b is endo, c is wrong, so a's first part is wrong but other options are worse. Wait no, re - check: Active transport uses energy. So the correct is movement against concentration gradient (a's first part is wrong. Wait no, the question is "Movement of substance against concentration gradient. It does not use chemical energy" (a). But active transport uses energy. Wait, no, the first part of a is correct (movement against gradient) but the second is wrong. But among options:

• a. Movement... against gradient (correct part) but no energy (wrong). But other options: b is endocytosis (vesicle), c is about diffusion (passive), d is passive. So the best is a (the first part is the key for active transport description, even if the second part is wrong. Maybe a typo in options. Because the definition of active transport is movement against gradient using energy.

1. Facilitated diffusion is a passive transport (no energy from cell). Option a: movement of ions only (no, can be other molecules). Option b: no ATP (facilitated diffusion is passive, so no ATP, but b says requirement of ATP (wrong). Option c: non - polar (facilitated diffusion is for polar or large molecules). Option d: no energy (correct as it's passive).
2. Osmosis is the movement of water from high to low concentration. Option a: proteins (wrong). Option c: low to high (wrong, that's active for solutes, but osmosis is water high to low). Option d: movement of gradients (wrong, movement of water).
3. In isotonic solution, water enters and exits at equal rates (cell remains stable). Option a: cell swells (hypotonic). Option b: cell shrivels (hypertonic). Option c: no movement (wrong, there is movement but balanced).
4. If the cell has 35% solution, then water is \(100 - 35=65\%\). Outside solution is 20%, so water is \(100 - 20 = 80\%\).
5. Osmosis is water from high to low. Outside water (80%) > inside (65%), so water exits the cell.
6. Hypertonic solution: outside has lower water (higher solute). Here, outside solution (20% solute) < inside (35% solute) (wait no: solute outside is 20%, inside 35%. So outside is lower solute (higher water). Wait no: hypertonic is higher solute outside. Wait, no:

• Solute inside: 35%, so water 65%. Solute outside:20%, water 80%. So outside has lower solute (higher water). Wait no, hypertonic is higher solute. Wait, no:
• If a cell is in a hypertonic solution, the solution has higher solute concentration than the cell. Here, cell has 35% solute, solution has 20% solute. So the solution is hypotonic (cell is hypertonic relative to solution). Wait no:
• Wait, the definitions:
• Hypotonic: solution has lower solute (higher water) than cell. So water enters cell.
• Hypertonic: solution has higher solute (lower water) than cell. So water exits cell.
• Here, water exits cell (from 80% outside (20% solute) to 65% inside (35% solute)). So the solution is hypotonic (cell is hypertonic). But the options:
• a. Hypertonic (solution has higher solute. But solution has 20% solute < cell's 35% solute. So no).
• b. Hypotonic (solution has lower solute (higher water) than cell. Correct as water exits cell (from high water outside to low inside).

Answer:

1. a
2. d
3. b
4. d
5. d
6. b
7. b