Specialised cells

• Erythrocytes

  Biconcave shape- larger SA

  Cytoplasm contains high amounts of haemoglobin- readily associates with oxygen

  No nucleus- more space

  Elastic membrane- flexible so can squeeze through narrow capillaries
• Neutrophils

  Very flexible- can squeeze through cell junctions

  Flexible- allows them to form pseudopodia (cytoplasmic projections) that engulf microorganisms

  Large number of lysosomes- digestive enzymes help destroy pathogens

  Flexible nuclear membrane- further helps penetrate cell junctions and thought to cause lobed nucleus
• Sperm Cells

  The head contains a nucleus with half the number of chromosomes

  The acrosome in the head contains digestive enzymes- breaks down the outer layer of egg cell

  The mid piece is packed with mitochondria- releases energy for tail movement

  The tail rotates- allows the cell to move towards the egg
• Root Hair Cell

  Root hairs- increase SA which increases rate of osmosis

  Thinner walls- shorter diffusion pathway/distance

  Permanent vacuole- contains cell sap which is more concentrated than soil water which maintains water potential gradient

  Contain mitochondria- for active transport of mineral ions
• Ciliated Epithelium

  Have cilia (hair like structures)- beat in a coordinated way to shift materials along the surface of the epithelium tissue

  Contain goblet cells- produce mucus which traps dust/dirt/microorganisms to prevent them entering vital organs
• Squamous Epithelium

  Consists of a single layer of flattened cells on a basement membrane- thin layer of cells forms a thin cross section which reduces the distance that substances have to travel

  Permeable- allows for easy diffusion of gases
• Palisade Cells

  Contain a large number of chloroplasts- maximises the absorption of light for photosynthesis

  Tall and thin shape- allows light to penetrate deeper before encountering another cell wall (cell walls absorb/reflect light)- also allows many cells to be densely packed together
• Guard Cells

  Inner cell walls are thicker (those closer to the stomata) while the outer cell walls are thinner (those further from the hole)- the difference in thickness allows the cell to bend when turgid

  The cytoplasm has a high density of chloroplasts and mitochondria- scientists believe these play a part in the opening of the stomata
• What is the role of erythrocytes?

  To transport oxygen to body cells
• What is the role of neutrophils?

  To engulf and digest pathogens