A2.2.7 - Unicellular Organisms

Question 1

The 8 Life Processes

Define MR HM

MR HM GREN

Answer 1

• (M) Metabolism
  → Chemical reactions take place within the cell(s)
• (R) Response to stimuli
  → Reacting to changes in external environment
• (H) Homeostasis
  → Maintenance of constant internal conditions
• (M) Movement
  → Have some control over their place & position

Question 2

The 8 Life Processes

Define GREN

MR HM GREN

Answer 2

• Growth
  → Increase in size over a period of time
  → In multicellular org.: ↑ no. of cells
• Reproduction
  → Production of offspring
• Excretion
  → Removal of metabolic waste products
• Nutrition
  → Intake/Production of nutrients

Question 3

Unicellular organisms

Which type of cells are unicellular?

Answer 3

All prokaryotes & some eukaryotes

Question 4

Unicellular organisms

How do unicellular organisms carry out processes compared to multicellular organisms?

Answer 4

Multicellular organisms often have whole groups of cells (organs) carrying out various functions

Question 5

Examples of unicellular functions

Examples of some unicellular functions

Answer 5

• Cell membrane: homeostasis; controls movement of materials in & out of cell
• Vacuoles:
  → isolation/storage of waste to prevent harm to cell
  → digestion for nutrition
• Mitochondria: energy production
• Ribosomes: protein synthesis for growth & repair

Question 6

Unicellular organisms

Examples of unicellular organisms

Answer 6

• Paramecium
  → Genus group of protozoa
  → Usually less than 0.25mm in size
  → Widespread in aquatic environment
  → Its cilia allows it to move
• Chlamydomonas (autotrophs)
  → Genus group of chlorophyta (green algae)
  → 10~30μm in diameter
  → Distributed everywhere (soil, fresh water, oceans, snow)
  → Has 2 flagella, a cell wall, a chloroplast & an ‘eye’ that detects light