Organisation of the Organism

Biology Chapter 2

Cell

Cell membrane

Controls movement in and out of cells

Cytoplasm

Where chemical or metabolic reactions take place

Nucleus

Contains DNA, stores genetic information and controls the activity of the cell

Mitochondria

Where aerobic respiration happens

Ribosome

Allows protein synthesis in the cytoplasm

Endoplasmic reticulum

System of membranes that helps in the transport of substances within the cell and in the synthesis of proteins and lipids.

Vacuole

Cell sap to keep cell turgid

Cell wall

Rigid to hold the shape of the cell, strengthens the cell

Chloroplast

Contain chlorophyll, which absorbs light energy for photosynthesis

Bacterial cell

only contains a cell wall made of peptidoglycan, cell membrane, cytoplasm, ribosomes, and plasmids

Plasmids

• are small, circular rings of DNA in the cytoplasm with extra genes outside the chromosomal DNA.

Tissue

Groups of cells with similar structures working together to perform a shared function

Organ

Group of tissues working together to perform a specific function

Organ system

Group of organs with related functions working together to perform body functions

Organism

Any living thing that can carry out all the basic processes of life independently.

Specialised Cells

• Specialised Cells have Specific Functions.

Specialised Cells	Specific Function	Location of Cell
Ciliated cells	Movement of mucus in the trachea and bronchi	Respiratory Tract, Fallopian Tube, Testes
Root Hair cells	Absorption	Roots
Palisade Mesophyll cell	Photosynthesis	Leaf Cells
Neurones	Conduction of electrical impulses	Everywhere in an organism
Red Blood cells	Transport of oxygen	Everywhere in an organism
Sperm and Egg cells/ovum (gametes)	For reproduction	In their respective gonads (glands)

Cilia

• specialized epithelial cells with hairlike projections. They use sweeping to-and-fro moment to move items or also can have a sensory function

  

Root hair cell

• specialized extensions epidermal cells located at the tips of roots to maximise water and mineral absorption

  

Palisade mesophyll cell

• elongated epidermal cell on the surface level which contains a lot of chloroplasts to maximise photosynthesis

  

Neurone

• specialized cells of the nervous system responsible for sensory reception, processing and transmitting information

  

Red blood cell

• Biconcave shaped discs without nucleus or mitochondria to maximise oxygen consumption

  

Sperm cell

• Specialized for fertilization having a streamlined body and a flagellum for swimming, numerous mitochondria for energy production and acrosomes on the head which produce enzymes to penetrate the egg

  

• Egg

Egg cell

• One of the largest cells in the body and also non-motile. Contains nutrients needed for initial development of zygote once it gets fertilized by the sperm.

  

Magnification

Refers to how many times larger an object appears when viewed through a microscope compared to its actual size

The general formula is represented in these ways:

Magnification=size of drawing size of specimen=image actual=IA Magnification=size of specimen size of drawing​=actual image​=AI​

Other Forms in Magnification Formula

• Actual size = image size ÷ magnification

• Image size = magnification x actual size

Unit Conversions (μm - micrometre)

• 1cm = 10mm

• 1mm = 1000μm

• 1μm = 0.001mm

Magnification does NOT have any units (‘x 50’ or ‘x 5000’)