Download - Lesson 12 levels of organisation (1)
Specialised Cells and Levels of Organisation
Lesson 12
Learning Objectives.
• Explain the structure and function of specialised cells: red blood cells, ciliated cells, palisade cells, xylem vessels, root hair cells, nerve cells, sperm cells, egg cells.
• Define the terms tissue, organ and organ systems with examples.
Red blood cells transport oxygen
cell surface membrane cytoplasm contains no nucleus
cytoplasm contains haemoglobin
bi-concave disc shape
allows more room for haemoglobin
increases surface area over which absorption of oxygen can occur
haemoglobin is a protein which carries the oxygen molecules
Ciliated cells move bacteria and dust away from the lungs
cilia
magnification X3000
nucleus
Cilia are small extensions of the cell. They beat rhythmically to sweep mucus, which has trapped bacteria and dust, away from the lungs
Root hair cells absorb minerals and water from the soil
cytoplasmcontains no chloroplasts as no photosynthesis is needed
root hairincreases surface area for absorption of water and mineral ions
Cross-section of a root hair cell
cell membrane semi-permeable, so will allow water and mineral ions into the cell
Xylem vessels transport water and minerals up the plant
xylem vessel
lignin
no cytoplasm
longitudinal sectioncross-section
water-proof and strong;helps support the plant
hollow: allows for continuous flow of water and dissolved mineral ions
xylem vessels are continuous tubes
Nerve cellsStructure:• These are extremely elongated
(long) cells• They have many branches at
both ends to connect to other nerve cells• The long axis (main branch) is covered in
fat to prevent the electrical impulses affecting the surrounding parts of your body
Function:• To carry nerve impulses around your body
Nerve Cells
Nerve cells transmit information in the form of electrical impulses
Direction of information
Match the cell type with the function.
Cell Type: Function:Ciliated cells conduction of water and supportRoot hair cells reproduction.Xylem vessels transport of oxygen.Palisade Cells movement of mucus in the
trachea.Nerve cells absorption.Red blood cells conduction of impulses.Sperm and Egg cells photosynthesis.
Levels of organisation
What you know so far:• Organelles – tiny structures found inside a cell.
» Nucleus, cytoplasm, ribosomes, etc.
• Cells – the basic unit of life.
A tissue is a group of cells of similar structure that perform a shared function
Animal tissues:muscle tissue
nervous tissue
upper epidermal tissue
palisade mesophyll tissue
spongy mesophyll tissue
lower epidermal tissue
Tissues found in the leaf
Cross-section of a leaf
An organ is a structure made of a group of tissues working together to perform specific functions
Plant organs include the stem and the leaves
heart
stomach
lungs liver
brain kidneys
An organ system is a group of organs that coordinate to perform related functions
In plants the shoot is an organ system consisting of leaves and the stem
lymphaticsystem
respiratorysystem
digestivesystem
excretorysystem
reproductivesystem
muscularsystem
skeletalsystem
nervoussystem
endocrinesystem
circulatorysystem
Levels of organisation
nerve cell nervous tissue
brain nervoussystem
Homo sapiens
smallest largest
cell tissue organ organsystems
organism
End of Chapter questions
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