6.4 - The Organisation and Specialisation of Cells Flashcards
What are the levels of organisation in multicellular organisms?
Specialised cells —> tissues —> organs —> organ system’s —> whole organism
Define differentiation
The process by which stem cells become specialised into different types of cells
What are Erythrocytes?
• type of red blood cells
• have a flattened Biconcave shape which increases their SA:V ratio —> essential to their role of transporting oxygen around the body
• no nuclei or many other organelles —-> increases the space available for haemoglobin
• flexible —> squeeze through narrow capillaries
What are neutrophils?
• type of white blood cell
• multi- loved nucleus —> easier for them to squeeze through small gaps to get to the site of infections
• granular cytoplasm contains many lysosomes that contain enzymes used to attack pathogens
• flexible shape allows them to engulf foreign particles or pathogens
What are sperm cells?
• male gametes
• function = to deliver genetic information to the female gamete
• have a flagellum —> capable of movement and contain many mitochondria to supply the energy needed to swim
• the acrosome in the head of the sperm contains digestive enzymes —> which are related to digest the protective layes around the ovum and allow the sperm to penetrate = results in fertilisation
What are palisade cells?
• present in the mesophyll contain chloroplasts to absorb large amounts of light for photosynthesis
• thin cell walls —> increasing the rate of diffusion of CO2
• large vacuole to maintain turgor pressure
• chloroplasts can move within the cytoplasm in order to absorb more light
What are root hair cells?
• present at the surfaces of roots near the growing tips
• long extensions called root hairs
• increase the surface area of the cell
• this maximises the uptake or water and minerals from the soil
What are guard cells?
• pairs of guard cells on the surfaces of leaves form small openings called stomata —> necessary for CO2 to enter plants for photosynthesis
• when guard cells lose water they become less swollen as a result of osmotic forces —> they change shape and the stomata closes to prevent further water loss from the plant
• cell wall not s guard cell is thicker on one side so the cell fore not change shape symmetrically as its volume changes
What is squamous epithelium?
• very thin due to the squat or flat cells that make it up —> because it’s only one cell thick
• it is present when rapid diffusion across a surface is essential —> forms the lining of the lungs and allows rapid diffusion of oxygen into the blood
What is ciliated epithelium?
• cilia on surface move in a rhythmic manner
• lines the trachea —> swafting mucus away
• prevents the particles which may be bacteria from reaching the alveoli once inside the lungs
• goblet cells secrete mucus which helps to trap dust, dirt and microorganisms
What is a cartilage?
• connective tissue found in the outer ear , nose and at the ends of and between the bones
• contains fibres , proteins elastin and collagen
• firm and flexible
• composed of chondrocyte cells embedded in an extracellular matrix
• prevents the ends of bones from rubbing together and causing damage
What is muscle tissue?
• needs to be able to shorten in length = contract in order to move bones which in turn move the different parts of the body
• skeletal muscle fibres —> contain myofibrils which contain contractile proteins
What is epidermis?
• single layer of closely packed cells covering the surfaces of plants
• usually covered by a waxy, waterproof cuticle to reduce water Loss
• stomata formed by a pair of guard cells that can open and close are present in the epidermis —> allow CO2 in and out and water vapour and oxygen in and out
What are xylem tissues?
• type of vascular tissue responsible for transport of water and minerals through the plant
• tissue is composed of vessel elements —> elongated, dead cells
• the walls of these cells are strengthend with a waterproof material called lignin —> provides structural support for plants
What is phloem tissue?
• type of vascular tissue in plants
• responsible for the transport of organic nutrients particularly sucrose from leaves and stems where it is made by photosynthesis to all parts of the plant where it is needed
• composed of columns of sieve tube cells separated by perforated walls called sieve plates
