6.4- Organisation And Specialisation Of Cells Flashcards
What are the levels of organisation in multicellular organisms?
Specialised cells = tissues = organs = organ systems = whole organism.
how are erythrocytes specialised.
Erythrocytes/ red blood cells:
- flattened biconcave shape- increases SA to V ratio. Essential to their role of transporting oxygen around body.
- In mammals, don’t have a nuclei- increases space available for haemoglobin .
- Flexible- able to squeeze through narrow capillaries.
how are neutrophils specialised?
Neutrophils are a type of white blood cell. Play an essential role in immune system.
- Multi-lobed nucleus - makes it easier to squeeze through small gaps to get to infections.
- Granular cytoplasm contains many lysosomes that contain enzyme used to attack pathogens.
How are sperm cells specialised?
Sperm cells = male gametes. Deliver genetic info to female gamete.
- Flagellum- aids movement.
- Many mitochondria- supplies energy needed to swim.
- Acrosome on head - contains digestive enzymes to break through protective layers around ovum and allow sperm to penetrate.
How are palisade cells specialised?
Present in the mesophyll.
- chloroplasts- absorb large amounts of light for photosynthesis.
- Cells are rectangular shapes - can be closely packed to form continuous layer.
- Thin cell walls - increases rate of diffusion of co2.
- Large vacuole- maintains turgor pressure.
- Chloroplasts can move in cytoplasm to absorb more light.
How are root hair cells specialised?
Present at the surfaces on roots near the growing tips.
1. Long extensions called root hairs- increase surface area. This maximises uptake of water and minerals from soil.
How are guard cells specialised?
Pairs of guard cells on the surfaces of leaves form small openings called stomata which are necessary for co2 to enter plants for photosynthesis.
- When guard cells lose water and become less swollen, stomata closes to prevent further water loss.
- Cell wall is thicker on one side- so cell doesn’t change shape symmetrically as its volume changes.
What is a tissue?
A tissue is made up of a collection of differentiated cells that have specialised functions. As a result each tissue is adapted for a a particular function within organisms.
What are the 4 main categories of tissue in animals and their adaption.
- Nervous tissue- support transmission of electrical impulses.
- Epithelial tissue- to cover internal and external body surfaces.
- Muscle tissue- to contract.
- Connective tissue- either to hold tissue together or as a transport medium.
Squamous epithelium.
specialised tissue made up of specialised squamous epithelial cells. Flat appearance .
- Very thin due to the flat cells that it consists of. Only one cell thick.
- Present when rapid diffusion across a surface is essential.
- Forms lining of the lungs and allows rapid diffusion of oxygen into blood.
Ciliated epithelium.
Specialised tissue made up of ciliated epithelial cells.
- Cells have hair like structures called cilia on one surface that move in rhythmic manner.
- Ciliated epithelium lines the trachea- causes mucus to be swept away from lungs.
- Goblet cells present - release mucus to trap any unwanted particles present. Prevents bacteria reaching alveoli.
Cartilage.
Connective tissue found in outer ear, nose, ends (and between) of bones.
- Contains fibres of proteins elastin and collagen. Firm + flexible.
- Composed of chondrocyte cells embedded in an extra cellular matrix.
- Cartilage prevents bones rubbing together and causing damage.
Muscle.
A tissue that needs to be able to shorten in length in order to move bones.
1. Skeletal muscle fibres contain myofibrils which contain contractile proteins.
Epidermis
A single layer of closely packed cells covering the surfaces of plants.
- covered by waxy, waterproof cuticle - reduces water loss.
- Presence of stomata- allow co2 and oxygen in and out.
Phloem tissue.
Type of vascular tissue in plants. Responsible for transport of organic nutrients (sucrose) from leaves and stems.
1. Composed of columns of sieve tube cells separated by perforated walls called sieve plates.
