This document discusses different types of specialized cells and their functions. It provides examples of: - Red blood cells that transport oxygen using hemoglobin. - Ciliated cells in the lungs that move mucus and trapped particles away from the lungs using cilia. - Root hair cells that absorb water and minerals from soil through their large surface area and semi-permeable cell membranes. - Xylem vessels that transport water and dissolved minerals throughout plants in a continuous flow through hollow, reinforced tubes. - Nerve cells that transmit electrical impulses along their long, branched structures to connect and communicate between different parts of the body.

1. Specialised Cells and Levels of
Organisation
Lesson 12

2. 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.

3. 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

4. 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

6. Root hair cells absorb minerals and water from
the soil
cytoplasm
contains no
chloroplasts as no
photosynthesis is
needed
root hair
increases 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

9. 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

10. Nerve cells
Structure:
• 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

11. Nerve cells transmit information in the
form of electrical impulses
Direction of information

12. Match the cell type with the function.
Cell Type: Function:
Ciliated cells conduction of water and support
Root 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.

13. 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.

14. 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

15. 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

16. 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
lymphatic
system
respiratory
system
digestive
system
excretory
system
reproductive
system
muscular
system
skeletal
system
nervous
system
endocrine
system
circulatory
system

17. Levels of organisation
nerve cell nervous
tissue
brain nervous
system
Homo sapiens
smallest largest
cell tissue organ organ
systems
organism

18. End of Chapter questions
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