2.1 Organisation of Cells

Question 1

what are the characteristics of unicellular organisms?

Answer 1

• contains only one cell
• doesn’t have tissues or organs
• can be either prokaryotic or eukaryotic
• always exposed to external environment
• passive transport
  e.g. bacteria

Question 2

what are the characteristics of colonial organisms?

Answer 2

• capable of living by themselves but evolved to live together
• better abled to detect and move towards food
  e.g. slime moulds

Question 3

what are the characteristics of multicellular organisms?

Answer 3

• eukaryotic cells
• can be made up of multiple different cells
• active transport
  e.g. tissuses

Question 4

what is a tissue?

Answer 4

A group of cells of the same type with the same function.
e.g. blood (animals) and phloem (plants)

Question 5

what is an organ?

Answer 5

Part of an animal or plantforming a structural unit which is made up of one or more tissues.
e.g. heart (animal) and leaf (plants)

Question 6

what is an organ system?

Answer 6

A group of organs that function together as a unit.
e.g. blood system (animal) and vascular system (plant)

Question 7

define specialisation providing examples

Answer 7

when a cell have specifc functions for an organism with distinct features.
e.g. red blood cells, guard cells

Question 8

define differenciation and provide specific examples

Answer 8

Differentiation is the process that a stem cell goes through to become specialised.
- all cells have the potential code to change into a specialised cell
- involves a cell ‘turning off’ certain codes which are not necessary for the specialised cell its turning into

Question 9

list 3 examples of specialised animal cells and descibe their structure and function

Answer 9

• red blood cell: concave disc shape, maximising surface area, has no nucleus. this allows it to travel faster, carrying oxygen and maximising the amount it can carry
• white blood cell: irregulat and large shape (has no specific shape). it kills/engulfs foreign bodies e.g. pathogens
• muscle cell: there are three types all different in structure, however, overall all are thin and long. they contract and shorten
• neurons: multiple parts (dentrite, axon, soma), over 1m long which allows it to carry electrical lessages from one body part to another and the signals to travel fast

Question 10

list 3 examples of specialised plant cells and descibe their structure and function

Answer 10

• epidermal cell: on the outside of the cell. it acts as a protection for the inside of the cell
• guard cell: at the bottom of the leaf and have muliple holes (stoma) which opens and closes. it enables gases to enter and leave
• trichome cell: hair shaped - pointy at the ends. it reflects light and secretes toxins (enzymes) to break down insects (predator)
• xylem/phloem: tubular shaped, walls are coveredby lignin. they transport water
• spongey mesophyll cell: irregular and loose shape. it allows the exchange of gases to occur

Question 11

what is the hierarchal system of the organisation of life from smallest to largest?

Answer 11

1. cell organelles (endoplasmic reticulum)
2. cell (human muscle cell)
3. tissue (cardiac, skeletal, smooth)
4. organ (muscle - gluteus maximus)
5. organ system (muscular system)
6. organism (human)
7. ecosystem (society)