Biology Study Notes: Cells, Diffusion & Osmosis

Practice questions covering cell structure, specialization, levels of organization, diffusion, and osmosis.

What characterizes a eukaryotic cell?

Eukaryotic cells have a nucleus and are found in multicellular organisms such as plants and animals.

What characterizes a prokaryotic cell?

Prokaryotic cells have no nucleus and are found in unicellular organisms such as bacteria.

Which organelles are found in plant cells but NOT in animal cells according to the notes?

Cell wall, permanent vacuole, and chloroplast.

What is the function of the mitochondria?

It is the site of respiration to make energy.

What is the function of the cell membrane?

It controls what enters and exits the cell.

What is the standard unit for measuring most cells?

The micrometer (symbol: $\mu m$).

What is the formula for calculating magnification?

$$\text{Magnification} = \text{Image Size} \div \text{Actual Size}$$

What is cell differentiation?

The process by which cells develop into many different types in order to carry out specific functions.

Where are adult stem cells mainly found in humans?

In bone marrow, adipose (fat) tissue, and blood.

What is the function of the myelin sheath on a neuron?

It speeds up signal transmission.

How do red blood cells facilitate efficient oxygen absorption?

They have a biconcave shape which increases surface area and they have no nucleus to allow them to carry more oxygen.

What is the purpose of the genetic information and enzymes in the head of a sperm cell?

The genetic information is for fertilization, and the enzymes help penetrate the egg cell membrane.

What is the specific function of ciliated cells?

They have cilia that beat back and forth to create a current and move substances along the respiratory tract and oviducts.

How are root hair cells specialized for absorption?

They have long hair-like extensions that greatly increase surface area for more efficient absorption of water and minerals.

Define 'Tissue' in the levels of organisation.

A group of similar cells that are specialized to perform a particular function.

Define an 'Organ System.'

When groups of organs work together to perform a particular function, such as the circulatory system.

What tissue in a plant leaf carries out photosynthesis?

Mesophyll (made up of palisade and spongy mesophyll cells).

What are cell membranes made of?

A lipid bilayer (two layers of fat) and proteins.

What is the difference between passive and active transport?

Passive transport does not require energy and moves molecules down the concentration gradient, while active transport requires energy and moves molecules against the concentration gradient.

Define diffusion.

The net movement of particles from a region of high concentration to a region of low concentration, down a concentration gradient, as a result of their random movement.

List four factors that affect the rate of diffusion.

1. Concentration gradient, 2. Temperature, 3. Surface area, and 4. Distance.

Why are alveoli surfaces kept moist?

To encourage gas molecules to dissolve easily for efficient exchange.

Define osmosis.

The movement of water molecules from a high water potential to a low water potential across a partially permeable membrane.

What happens to an animal cell placed in a dilute solution?

Water moves into the cell by osmosis, causing the cell to swell and potentially burst ($\text{lysis}$).

What is the state of a plant cell when its cytoplasm and vacuole swell and push against the cell wall?

Turgid.

What is plasmolysis?

When the cell membrane pulls away from the cell wall due to excessive water loss.