Specialised cells Flashcards
What are the levels of organisation in a multicellular organism?
Specialised cells- Tissue- Organ- Organ system- Whole organism
How are specialised cells formed?
They are differentiated to carry out a specific role/ function within the body
Erythrocytes (red blood cells)
Transport oxygen around the body
Flattened biconcave shape- increase SA:V ratio
Do not have a nucleus- increase space available for haemoglobin
Flexible- can squeeze through narrow capillaries
Neutrophils (white blood cell)
Play a role within the immune system
Multi lobed nucleus- easier to squeeze through small gaps to get to the site of infection
Cytoplasm contains many lysosomes- contain enzymes that can attack pathogens
Sperm cells
Male gametes- deliver information to the female gamete
Have a flagellum- capable of movement
Many mitochondria- provide energy needed for movement
Acrosome contains digestive enzymes- released to digest protective layers around the egg cell so the sperm cell can penetrate
Palisade cells
Contain many chloroplasts- obtain light for photosynthesis
Rectangular shaped- closely packed together to form a continuous layer
Thin cell walls- increase rate of diffusion for CO2
Chloroplasts can move within the cytoplasm to absorb more light
Large vacuole to maintain turgor pressure
Root hair cells
Have root hairs- increase surface area to maximise uptake of water and minerals from the soil
Guard cells
Pairs form stomata- essential for gas exchange
Guard cells lose water- less swollen- change shape to close stomata- prevent further water loss
What is a tissue?
Collection of differentiated cells that are working together to carry out a specific function
Squamous epithelium
Thin- one cell thick so rapid diffusion of oxygen into the lungs can occur
Ciliated epithelium
Line the trachea
Goblet cells release mucus, trapping unwanted particles so they cannot reach the alveoli
Cells have hair like structures, cilia which beat in a rhythmic manner to sweep away mucus
Epidermis
Layer of closely packed cells covering surface of plants
Covered by waxy cuticle to reduce water loss
Stomata allow for gas exchange
Xylem
Transport of water and minerals throughout the plant
Composed of elongated dead cells
Walls strengthened with lignin, providing structural support
Phloem
Transport of sucrose from the leaves to the rest of the plant
Columns of sieve tube cells separated by sieve plates
What is an organ?
Collection of tissues that work together to perform a particular function within an organism
