Cell Transport and Homeostasis

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Questions and Answers

Which of the following is NOT a type of passive transport?

Facilitated diffusion

Simple diffusion

Exocytosis (correct)

Osmosis

What is the difference between simple diffusion and facilitated diffusion?

Simple diffusion moves molecules down a concentration gradient, facilitated diffusion moves molecules against a concentration gradient.

Simple diffusion requires a transport protein, facilitated diffusion does not.

Simple diffusion is faster than facilitated diffusion.

Simple diffusion is used for small nonpolar molecules, facilitated diffusion is used for large molecules or polar molecules. (correct)

In which type of solution will a cell shrink?

Hypotonic

Hypertonic (correct)

Isotonic

None of the above

What does the term 'concentration gradient' refer to?

The difference in concentration of a substance between two areas. (B) Signup and view all the answers

Which of the following molecules is most likely to move across a cell membrane by simple diffusion?

Carbon dioxide (CO2) (A) Signup and view all the answers

What is the role of ATP in active transport?

ATP provides energy to move molecules against a concentration gradient. (A) Signup and view all the answers

Which of the following is NOT a characteristic of active transport?

Moves molecules down a concentration gradient. (C) Signup and view all the answers

Which of the following is an example of active transport?

The movement of sodium ions from the inside of a cell to the outside of a cell. (B) Signup and view all the answers

What happens to a cell placed in a hypertonic solution?

The cell shrivels (B) Signup and view all the answers

Which type of solution has an equal concentration of solutes compared to the cell's cytoplasm?

Isotonic solution (B) Signup and view all the answers

When a cell is placed in a hypotonic solution, what is the expected outcome?

The cell swells (D) Signup and view all the answers

What is the role of active transport in cellular processes?

It requires energy to move molecules against their concentration gradient (A) Signup and view all the answers

If a cell is in a 10% NaCl solution and it swells, what can be inferred about the solution's tonicity?

It is hypotonic to the cell (C) Signup and view all the answers

What characterizes a solution that is hypertonic relative to a cell?

Higher solute concentration than the cell (A) Signup and view all the answers

What type of transport mechanism is used when water moves through the cell membrane?

Osmosis (C) Signup and view all the answers

In a situation where the cell is in a 15% NaCl solution, what will happen to the cell?

The cell shrivels (B) Signup and view all the answers

Which type of transport is used by nerve cells to secrete neurotransmitters?

Exocytosis (B) Signup and view all the answers

Which type of transport is used by white blood cells to engulf bacteria?

Phagocytosis (C) Signup and view all the answers

Which of the following types of transport is responsible for maintaining blood pressure?

Osmosis (C) Signup and view all the answers

Which of the following is NOT a characteristic of a stimulus?

It always results in a negative feedback loop. (D) Signup and view all the answers

In a positive feedback loop, the output of a system:

Amplifies the initial stimulus. (D) Signup and view all the answers

Which of the following is NOT an example of a positive feedback loop?

Body temperature regulation. (C) Signup and view all the answers

Which of the following is a characteristic of negative feedback loops?

They help restore equilibrium to a system. (D) Signup and view all the answers

What is meant by the term "selectively permeable" as it relates to the cell membrane?

The cell membrane is composed of proteins and lipids, allowing only specific molecules to enter or exit. (D) Signup and view all the answers

Which of the following molecules would be able to pass through the cell membrane most easily?

A small, nonpolar molecule. (B) Signup and view all the answers

What is the main function of the cell membrane in maintaining homeostasis?

To control the movement of substances into and out of the cell. (D) Signup and view all the answers

Which of the following types of transport would require energy from the cell?

Active transport. (C) Signup and view all the answers

Study Notes

Cell Transport

Students will analyze the relationship between structures and functions of living cells.
They'll investigate the role of cellular transport (active, passive, osmosis) in homeostasis.

Homeostasis

Homeostasis is an organism's need to stay stable by regulating internal conditions.
It's a dynamic equilibrium, meaning things stay within a range, not always the same.
Examples of regulated factors include pH, temperature, and blood sugar.
Organisms respond to stimuli (changes in the environment) to maintain homeostasis.
Response is a change within the organism in reaction to a stimulus.

Feedback Mechanisms

Feedback mechanisms help maintain homeostasis.
They use system output to signal and change input, stabilizing or amplifying the system response.
Feedback can be positive or negative.

Positive Feedback

In a positive feedback loop, the output intensifies the response, creating a cycle of increasing effect.
Examples include childbirth (hormones, contractions, pressure), and fruit ripening (ethylene signaling).

Negative Feedback

In a negative feedback loop, the output causes a counter-response, returning the system to a set point (stabilization).
Examples include body temperature regulation, water concentration (osmoregulation), and blood sugar regulation.

Cell Membrane

Homeostasis is regulated at a cellular level, with the cell membrane controlling the movement of substances into and out of the cell.
Cell membranes are selectively permeable, meaning they are picky about what can pass through.
- Small, nonpolar, and/or neutral molecules pass easily
- Large and/or polar molecules pass less easily.

Types of Cell Transport

Active transport requires energy (ATP) to move substances against the concentration gradient (low to high).
- Examples: molecular pumps, exocytosis, and endocytosis.
Passive transport does not require energy. Substances move down the concentration gradient (high to low). Types include:
- Simple diffusion – substances move directly across the membrane; examples: O2 and CO2
- Facilitated diffusion – substances use transport proteins to move across the membrane; examples: glucose and calcium.
- Osmosis – the passive transport of water across a membrane from high water concentration to low concentration.
- Water moves in three types of solutions
  - Hypertonic - Water concentration is lower outside the cell, water leaves the cell, causing cells to shrivel
  - Hypotonic - Water concentration is higher outside the cell, water moves into the cell, causing cells to swell
  - Isotonic - Equal water concentration between inside and outside of the cell.
Endocytosis – Taking large particles into the cell using vesicles
Exocytosis – Exporting materials out of the cell using vesicles.
Phagocytosis – "cell eating," engulfing solids
Pinocytosis – "cell drinking," engulfing liquids

Summary

A chart summarizing the type of transport, examples of substances moved, and how it maintains homeostasis is also provided.

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Description

Explore the critical concepts of cell transport and homeostasis in living organisms. This quiz will focus on the mechanisms that help maintain stability through various feedback systems and the role of cellular processes in these dynamics. Test your understanding of active and passive transport, osmosis, and feedback mechanisms.