specialised cells Flashcards
outline the levels of organisation of a multicellular organism in order
specialised cells –> tissues –> organs –> organ systems –> whole organism
define specialised
having particular structure to serve a specific function
define differentiated
specialised to carry out very specific functions
define cell
the smallest structural and functional unit of an organism
define tissue
collection of cells, of one or more types, working together to perform a function
define organ
a collection of tissues working together to perform a function
define organ system
collection of organs working together to perform a function
explain why multicellular organisms have specialised cells
- bc they are complex and require different organ systems to function
- specialised cells carry out functions very efficiently
- if no cells were specialised, no life process would be done as efficiently
explain how erythrocytes are specialised for their function
- flattened biconcave shape - increases SV ratio
- flexible - able to squeeze through narrow capillaries
- no nuclei & many other organelles in mammals - more space for haemoglobin
- essential for transporting O2
explain how neutrophils are specialised for their function
- multi-lobed nucleus to squeeze through small gaps to get to the site of infection
- granular cytoplasm contains lysosomes to contain enzymes used to attack pathogens
- essential to combat infections as part of immune system
explain how sperm cells are specialised for their function
- tail/flagellum - capable of movement
- many mitochondria - energy supply for swimming
- acrosome - contains digestive enzymes to allow sperm to penetrate the ovum and fertilise
- essential for delivering genetic information to female gametes
explain how palisade cells are specialised for their function
- chloroplasts - absorb large amounts of light for photosynthesis
- rectangular box shape - closely packed to form continuous layer
- thin cell walls - increased rate of diffusion of CO2
- large vacuole - maintain turgor pressure
- chloroplasts able to move within cytoplasm to absorb more light
- essential to maximise rate of photosynthesis
explain how root hair cells are specialised for their function
- long extensions (root hairs) - increase surface area of cell
- essential to maximise uptake of water + minerals from the soil
explain how guard cells are specialised for their function
- form stomata - allow CO2 to enter/exit plants
- when they lose water, they become less swollen due to osmotic forces, change shape and stoma closes to prevent further water loss from plant
- cell wall is thicker on one side so the cell does not change shape symmetrically as volume changes
state 4 main categories of tissue in animals
- nervous: support transmission of electric impulses
- epithelial tissue: cover body surfaces
- muscle: adapted to contract
- connective: hold tissues together/transport medium
explain how squamous epithelium is specialised for it function
- very thin - one cell thick & the cells are flat - small diffusion distance
- present when rapid diff. across a surface is essential (lining of lungs)
explain how ciliated epithelium is specialised for its function
- composed of ciliated epithelial + goblet cells
- cilia move in rhythmic manner, causing mucus to be swept away from the lungs
- tissue prevents particles & pathogens from reaching the alveoli once inside lungs
- found in the trachea
explain how goblet cells are specialised for their function
release mucus to trap unwanted particles from the air
explain how cartilage is specialised for its function
- firm + flexible - composed of chondrocyte cells embedded in extracellular matrix containing elastin & collagen
- prevents ends of bones rubbing together & causing damage
- found in outer ear, nose, ends of & between bones
explain how muscle tissue is specialised for its function
contain myofibrils that contain contractile proteins - allow muscle tissue to contract in order to move bones which moves diff parts of the body
explain how epidermis tissue is specialised for its function
- single layer of closely packed cells that covers surface of plants
- covered by waxy waterproof cuticle - reduces loss of water
- stomata (formed by guard cells) - allow CO2, H2O and O in and out
explain how xylem tissue is specialised for its function
- vascular tissue responsible for transport of water and minerals throughout plants
- vessel elements (elongated dead cells) walls of them strengthened with lignin - structural support for plants
explain how phloem tissue is specialised for its function
- vascular tissue responsible for transport of organic nutrients (sucrose) from leaves and stems where it is made to other parts of the plant
- composed of columns of sieve tube cells separated by perforated walls (sieve plates)
state 3 examples of organ systems in animals
- digestive system
- cardiovascular system
- gaseous exchange system
describe the function of the digestive system
takes in food, breaks down large insoluble molecules into small soluble ones, absorbs nutrients into the blood, retains water needed by body and removes undigested material from body
describe the function of the cardiovascular system
moves blood around the body to provide a transport system for the substance it carries
describe the function of the gaseous exchange system
brings air into the body so O2 can be extracted for respiration and CO2 can be expelled
