• Improve Tuition
  • Improve Tuition
  • Improve Tuition
  • Improve Tuition
  • Improve Tuition

Study Guide : Cells and Organisation

 

All living organisms are made up of cells. Cells are the building

blocks of life. Because there are a vast number of cells, some

cells are specialized to ensure they provide a specific function.

They can only be viewed by using a light microscope. By

placing a cell under the microscope, and using a stain this

ensures the cell is visible to the human eye.When drawing

cells it is important to use a pencil and draw as much detail

as possible.

 

To calculate the total magnification you multiply the eyepiece

lens magnification by the objective lens magnification.

 

TOTAL MAGNIFICATION = = EYE PIECE LENS       

MAGNIFICATION X OBJECTIVE LENS MAGNIFICATION

Specialized cells

PART

FUNCTION

FOUND IN

Cell membrane

Outer part of cell, which acts as a barrier controlling what goes in and out

Animal and plant cells

Cytoplasm

This is where all the reactions occur

Animal and plant cells

Nucleus

Controls the cell and carries all the genetic information

Animal and plant cells

Chloroplast

This is where photosynthesis occurs as it contains chloroplasts

Plant cells

Vacuole

Keeps the cell firm as it contains a liquid call cell sap

Plant cells

Cell wall

Outer wall which supports the cell ensuring its structure

Plant cells

 

Animal cells and plant cells


Animal cells have a very irregular shape and often look uneven

and unequal however plant cells have a very regular shape.

Plant cells and animal cells differ in function due to the

different parts they have.

This is highlighted in the diagram below.

 

Type of Cell

Function

Special Features

Red Blood cell

To carry oxygen in the blood.

Has hemoglobin which carries the oxygenHas a concave, donut like shapeDoes not have a nucleus so it can carry more oxygenHas a large surface area to allow to carry more oxygen

Nerve Cell

Carries nerve impulses (messages) from the body to the brain and back again.

They are long, have many connections so can reach every corner of the bodyThey carry electrical signals so the impulse is relayed quickly

Egg cell

To join with the sperm cell and provide nutrition for the zygote (new cell) when formed.

It is large and contains lots of cytoplasm for reaction to take place.

Sperm Cell

To reach the egg cell and join.

Has a tail, which allows it to move.Also has a head to carry genetic information and penetrate the egg cell.

Root Hair Cell

To absorb water and minerals.

Has a large surface area, which allows it to absorb as much as possible.

Palisade cell (Leaf cell)

To absorb sunlight to allow the plant to photosynthesize.

Has a large surface area and many chloroplasts, which allow it to absorb as much sunlight as possible.

 

Unicellular organisms

A unicellular organism is one that only has one cell for

example bacteria, protozoa and fungi.

 

Bacteria

Bacteria are very small cells, they differ from normal animal

cells as they do not contain a nucleus so the DNA is either

floating free or kept in small containers called plasmids they

also may have a tail like structure usually called a Flagellum

allowing the cell to move.

 

Protozoa

Protozoa are also unicellular organisms however it has certain

characteristics that are similar to animal cells.

It has feet like projections that allow it to move and take food

into the cell.

Yeast

Yeast is commonly used in bread making and making alcohol

as it converts sugar into alcohol.

Yeast is similar to plant cells in that, they have cells walls

which means they can absorb sugars.

 

Cells, tissues, organs and systems

Tissues are a group of cells working together to perform a

specific function e.g. muscle, lining the intestines or lungs.

Organs are a group of tissues which work together to perform

a larger task e.g. heart, lungs, stomach.

Organ systems are a group of organs working together to

perform a task in the body e.g.

Cardiovascular system, reproductive system.

 

EXAM TIP


Never call the nucleus the “brain of the cell”, it is not a very

good description and will not get you any marks.

Learn the difference between animal and plant cells, as it is

a very common question.



 Check the box if you are a member of Improve Tuition
 Email me more information and special offers