B1 - Cell structure and Transport

eyepiece

closes lens to eye, magnification of x10

arm

holds the eyepiece and lens above the stage

coarse focus

focuses the image to see clearly

fine focus

focuses the image to see clearly and sharply

revolving nose piece

holds the objective lens, can rotate

Objective lens

has 3 lenses of different strength to magnify the image more clearly

stage

where you put a microscope slide, clips hold the slide in place

diaphragm

Controls the amount of light that goes onto the microscope slide

light

projects light onto microscope slide, can use a mirror or light bulb

base

very heavy to prevent the microscope from falling over

Two types of microscopes

1. light microscope - used in school
2. electron microscope

How to use a light microscope

1. place the slide with the specimen onto the stage.
2. Ensure the lowest power objective lens is in place and the stage is as high as possible.
3. look through the eyepiece
4. adjust the coarse and fine focusing dials until the image is clear and sharp
5. To increase magnification, twist the nose piece so the next highest objective lens is in place
6. adjust the coarse and fine focusing dials again until the image is clear

A microscope has x5 eyepiece lens. Describe how to use this microscope to observe a prepared slide of root hair cells at a magnification of x50

The eyepiece lens magnifies x5 so you will need an objective lens of x10 to make the total magnification x50. Place the root hair cell on the stage and rotate the nosepiece to x10. You turn the coarse focus knob to see the root hair cells clearly and adjust the fine focus so the image is clear and sharp

cell membrane

controls what goes in and out

chloroplast

absorbs light energy to make food by photosynthesis and contains chlorophyll

cell wall

made of cellulose, strengthen the cells and gives it support

vacuole

filled with cell sap, keeps the cell rigid to support the plant

cytoplasm

liquid gel in which most of the chemical reaction need for life take place

nucleus

contains DNA, controls all the activities of the cell

mitochondria

releases energy during respiration

ribosome

where protein synthesis takes place

3 cells that plants have that animal don't

1. chloroplast
2. vacuole
3. cell wall

Nerve cell - Location, Function and Adaptation

Location: Around the body
Function: To carry electrical impulses from one part of the body to another
Adaptation: Long axon carries nerve impulses from one part of the body to another.
Lots of Mitochondria to release energy needed to make chemicals which help cells to communicate

Muscle cells - Location, Function and Adaptation

Location: walls of blood vessels and hollow organs
Function: specialized to contract and relax
Adaptation: Lots of mitochondria, to release lots of energy for movement through aerobic respiration.
Special contractions protein to help change the size of muscle for movement

Sperm cells - Location, Function and Adaptation

Location: male parent
Function: fertilizes an egg
Adaptation: long tail to help the sperm move through the reproductive system.
Lots of Mitochondria which releases energy needed for movement

Red blood cells - Location, Function and Adaptation

Location: In blood
Function: Picks up oxygen from the air in your lungs, carry to the cell where needed
Adaptations: Lots of haemoglobin which binds to the oxygen.
No nucleus or mitochondria so more space for haemoglobin so more oxygen can be carried

Root hair cells - Location, Function and Adaptation

Location: close to the tips of growing root
Function: help them to take up water and mineral ions efficiently.
Adaptation: extended, long root hair increases the surface area so more water can enter (shape).
Many mitochondria are needed to transfer enough energy to help minerals and ions move into the cell

Palisade (leaf) cells - Location, Function and Adaptation

Location: Plants
Function: Can make their own food by photosynthesis
Adaptation: Many chloroplast with chlorophyll mean more light can be absorbed for photosynthesis. Photosynthesis is how a plant cell makes food

Definition of diffusion and where does it occur

Movement of particles from an area of higher concentration to an area of lower concentrations, occurs across cell membrane

in which states can molecules diffuse?

molecules in liquids and gases are constantly moving and bumping into each other. This means that they tend to spread out.

How does the temperature affect the rate of diffusion?

An increase in temperature affects particles by diffusing very quickly using more kinetic energy

concentration gradient

Difference in concentration between two areas.

large concentration gradient

small concentration gradient

How does the concentration gradient affect the rate of diffusion?

The larger the difference in concentration, the higher the rate of diffusion.

what substances diffuse into animal cells?

Oxygen (from the lungs) and glucose (from digested food).

What substances diffuse out of animal cells?

Carbon dioxide (excreted via the lungs) and urea from liver cells (excreted via the kidneys).

What substance diffuses into plant leaves?

Carbon dioxide (for photosynthesis).

What substances diffuse out of plant leaves?

Oxygen and water (through the stomata)

3 features of a good gas exchange

1. Folded shape → larger surface area so more space for molecules to enter

2. Thin → to provide a shorter diffusion distance so diffusion rate increases

3. (in animals) efficient blood supply, always enough oxygen to keep a high concentration gradient.

importance of active transport

When molecules need to move from low concentration to high concentration organisms use active transport. This requires energy to move molecules against a concentration gradient with the help of transport protein.