6.4 - Organisation & Specialisation of Cell Flashcards
State the organisation of multicellular organisms.
specialised cells > tissues > organs > organ systems > whole organism
How are erythrocytes specialised to perform their function?
- Small & flexible to fit throughtiny capillaries
- No nuclei to allow for haemoglobin
- Biconcave shape to provide large SA for faster diffusion
How are neutrophils specialised to perform their function?
- Multi-lobed nucleus to help movement through membranes, and to reach site of infection
- Many ribosomes - to manufacture digestive enzymes
- Many lysosomes - to hold lysozymes
- Membrane-bound receptors - to recognise pathogens
How is a sperm cell specialised to perform its function?
- Flagellum to enable rapid movement
- Acrosome - has enzymes to digest ovum surface
- Many mitochondria - to provide energy for rapid movement
How are palisade cells specialised to perform their function?
- Cytoplasmic streaming - where the chloroplasts move around within the cell to absorb more light
- Elongated, rectangular shape for tight and efficient packing in mesophyll
- Many chloroplasts to absorb light
How are root hair cells specialised to perform their function?
- Long root hair extensions - increasing SA for H2O uptake
- Active pumps in plasma membrane to absorb mineral ions by active transport
- Thin cell wall - reduces diffusion distance
How are guard cells specialised to perform their function?
- Active pumps in plasma membrane - to move ions in and out to control water potential which controls stomatal aperture
- Cell wall of thicker on one side - cell will not change shape symmetrically as its volume changes
- Large vacuole - to take up water and open stoma
Define tissue
Define organ
Define organ system
Tissue: Collection of specialised cells working together to perform a specific function
Organ: A collection of tissues working together to perform a common function
Organ System: A collection of 2 or more organs working together to perform a life function such as excretion or transport
What are the 4 categories of tissue and their respective roles?
- Nervous tissue - supports electrical impulse transmission
- Epithelial tissue - covers internal and external body surfaces
- Muscle tissue - contracts
- Connective tissue - transport medium or holds other tissues together
How are squamous epithelial tissue specialised?
- Has squamous epithelial cells - flat to cover large area, and thin to provide short diffusion distance
- Lines lung surfaces
- Can be ciliated - has goblet cells that secrete mucus and the cilia waft the mucus away
- Lines trachea
What are the roles and adaptations of cartilage?
- Connective tissue found in outer ear, between bones and nose
- Contains elastin and collagen fibres
- Cartilage is firm, flexible and has chondorcyte cells that secrete collagen
- Prevents bones from rubbing together causing damage
What are the roles and adaptations of muscle?
Types
- Smooth - single cells that can contract
- Skeletal Muscle - forms multinucleate fibres with actin and myosin filaments that slide past one another
- Cardiac Muscle - forms cross-bridges
What are types of specialised plant tissue?
Epidermis tissue - adapted to cover plant surfaces
Vascular tissue - transport of water/nutrients
What are the roles and adaptations of epidermis tissue?
- Layer of closely packed cells covering plant surface - Covered by waxy waterproof cuticle reducing water loss - Stomata are present on surface of epidermis to allow gas and water exchange.
What are the roles and adaptations of xylem tissue?
- Vascular tissue responsible for water and mineral transport
- Tissue composed of vessel elements - elongated dead cells
- Walls of these cells strengthened by waterproof lignin which provides structural support
