Biology Osmosis and Science Skills

osmosis

The passive movement of water from a low solute concentration to a high solute concentration through a selectively permeable membrane.

diffusion

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

tonicity

Tonicity describes the relative concentration of solutes in two solutions separated by a semipermeable membrane.

hypertonic solution

A solution with a higher solute concentration compared to another, causing water to move into it.

hypotonic solution

A solution with a lower solute concentration compared to another, causing water to move out of it.

isotonic solution

A solution with equal solute concentration compared to another, resulting in no net water movement.

plant cells in a hypotonic solution

They swell and become turgid due to water intake.

animal cells in a hypotonic solution

They may swell and burst (lyse).

cells in a hypertonic solution

Water leaves the cells, causing them to shrink.

molecule that can freely diffuse

Oxygen (O₂) or carbon dioxide (CO₂).

ions and membrane diffusion

Because they are charged and cannot pass through the nonpolar lipid bilayer.

factors affecting the rate of diffusion

Temperature, concentration gradient, surface area, molecule size, and polarity.

aquaporins

Protein channels that facilitate faster water movement across the membrane.

percentage change in mass formula

% Change = (Final Mass - Initial Mass) / Initial Mass × 100

type of transport for osmosis and diffusion

Passive transport - they do not require energy.

What is the purpose of developing aims and questions in a biology investigation?

To guide the direction of the investigation and focus data collection.

What are independent, dependent and controlled variables?

Independent: the variable changed; Dependent: the variable measured; Controlled: variables kept constant.

What is a hypothesis?

A testable prediction that explains what might happen in an experiment.

Why are hypotheses important?

They provide a focus for the investigation and allow predictions to be tested.

What is a controlled experiment?

An experiment in which only one variable is changed at a time to test its effect.

What are examples of investigation methodologies?

Case study, classification and identification, controlled experiment, correlational study, fieldwork, literature review, modelling, simulation, product/system development.

Why is it important to select appropriate equipment and procedures in an investigation?

To ensure valid, accurate and reliable data are collected and sources of error are minimised.

What is the difference between qualitative and quantitative data?

Qualitative data is descriptive; quantitative data is numerical.

What must be considered when designing sampling techniques?

Sample size, representation, potential bias, and sources of error or uncertainty.

Why is collaboration important in scientific investigations?

It allows for more perspectives, verification, and division of tasks within constraints.

What is the purpose of a risk assessment in scientific investigations?

To identify and minimise potential safety hazards using SDS and lab safety guidelines.

How is primary data different from secondary data?

Primary data is generated by the researcher; secondary data is obtained from existing sources.

What are accuracy and precision?

Accuracy: closeness to the true value; Precision: consistency of repeated results.

What are repeatability and reproducibility?

Repeatability: consistent results within the same lab; Reproducibility: consistent results across different labs.

What are random and systematic errors?

Random: unpredictable variation; Systematic: consistent bias in measurement.

How do you identify outliers?

Data points that deviate significantly from the rest of the data set.

Why should experiments be repeated?

To improve the reliability and robustness of results.

How can investigations be improved?

By refining methods, controlling variables more effectively, and reducing sources of error or bias.

What is an evidence-based conclusion?

A conclusion that is directly supported by experimental data and not opinion.

How do you evaluate if evidence supports a hypothesis?

Compare results to the predicted outcomes stated in the hypothesis.

What are the limitations of scientific conclusions?

Limited data, uncontrolled variables, sample size, or measurement uncertainty.

What is the role of scientific reasoning in conclusions?

To justify findings logically based on the data and context.

Why is it important to distinguish opinion from evidence?

To ensure conclusions are scientifically valid and not biased or anecdotal.