Animal & Plant Cells (Cambridge O Level Biology)

Animals

• The main features of animals:
  • They are multicellular
  • Their cells contain a nucleus with a distinct membrane
  • Their cells do not have cellulose cell walls
  • Their cells do not contain chloroplasts (so they are unable to carry out photosynthesis)
  • They feed on organic substances made by other living things
  • They often store carbohydrates as glycogen
  • They usually have nervous coordination
  • They are able to move from place to place

A typical animal cell

Plants

• The main features of plants:
  • They are multicellular
  • Their cells contain a nucleus with a distinct membrane
  • Their cells have cell walls made out of cellulose
  • Their cells contain chloroplasts (so they can carry out photosynthesis)
  • They feed by photosynthesis
  • They store carbohydrates as starch or sucrose
  • They do not have nervous coordination

A typical plant cell

Cell Structures Found in Both Animal and Plant Cells Table

Cell Structures Found Only in Plant Cells Table

Animal and Plant Cell Diagrams

An animal and plant cell as seen under a light microscope; only larger structures are visible under a light microscope so smaller structures such as ribosomes will not be visible

Identifying Cell Structures and Function

• Within the cytoplasm, the following organelles are visible in almost all cells except prokaryotes when looking at higher magnification (i.e. using an electron microscope):
  • Mitochondria (singular: mitochondrion) are organelles found throughout the cytoplasm
  • Ribosomes are tiny structures that can be free within the cytoplasm or attached to a system of membranes within the cell known as Endoplasmic Reticulum
    • Endoplasmic reticulum studded with ribosomes looks rough under the microscope; this gives rise to its name of Rough Endoplasmic Reticulum (often shortened to R.E.R.)
  • Vesicles can also be seen using a higher magnification - these are small circular structures found moving throughout the cytoplasm

Structures in an animal cell visible under a light microscope and an electron microscope

Structures in a plant cell visible under a light microscope and an electron microscope

• To record the observations seen under the microscope (or from photomicrographs taken) a labelled biological drawing is often made
• Biological drawings are line pictures which show specific features that have been observed when the specimen was viewed
• There are a number of rules/conventions that are followed when making a biological drawing

Guidelines for microscope drawings

• The conventions are:
  • The drawing must have a title
  • The magnification under which the observations shown by the drawing are made must be recorded
  • A sharp HB pencil should be used (and a good eraser!)
  • Drawings should be on plain white paper
  • Lines should be clear, single lines 
  • No shading
  • The drawing should take up as much of the space on the page as possible
  • Well-defined structures should be drawn
  • The drawing should be made with proper proportions
  • Label lines should not cross or have arrowheads and should connect directly to the part of the drawing being labelled
  • Label lines should be kept to one side of the drawing (in parallel to the top of the page) and drawn with a ruler
• Drawings of cells are typically made when visualising cells at a higher magnification power, whereas plan drawings are typically made of tissues viewed under lower magnifications (individual cells are never drawn in a plan diagram)

Biological Drawing of an Animal Cell

An example of a tissue plan drawn from an electron micrograph of an animal cell

Biological Drawing of a Plant Cell

An example of a tissue plan drawn from an electron micrograph of a plant cell