Download UNIT 2 CELLS AND SYSTEMS

UNIT 2
CELLS AND SYSTEMS
Topic 1 Living Organisms
What do all living things have in common?
1) need energy
2) respond and adapt to their environment
3) reproduce
4) grow
5) produce wastes
6) made of cells
Topic 2 Microscopes and Cells
Microscopes – compound light microscopes – use more than one lens – magnify up to
2000 x - electron microscopes up to 2000000 x
How to calculate magnification : magnification of objective lens x magnification of
eyepiece lens.
How to calculate field of view. 1) Measure the diameter of the field of view on low
power. 2) for medium-power = low-power field of view x low-power lens
Medium-power lens
Topic 3 The Cell and Its Structures
Parts of an animal cell
cell membrane – surrounds cell and controls the passage of materials into and out of
the cell
cytoplasm – acts like blood in our bodies, moving materials such as oxygen and
food to the organelles and supports other organelles in cell
nucleus – contains genetic material that controls growth and reproduction –
surrounded by nuclear membrane
vacuoles – storage for food, wastes etc. – surrounded by a membrane
mitochondria – break down food particles to produce energy for the cell
Parts of a plant cell
membrane, cytoplasm, nucleus, vacuoles
cell wall – thick and rigid to give cell support
chloroplasts – where photosynthesis takes place
Topic 4
Fluid Movement in Cells
Diffusion in cells: ex. carbon dioxide passes through the cell membrane of an amoeba –
inside the cell CO2 is being produced, so there is a higher concentration of CO2 in the
cell – therefore, by diffusion, CO2 moves out of the cell until the concentration of CO2 is
equal on both sides of the cell membrane
Osmosis in cells: water is important to cells because it dissolves many substances the
cell needs – when a cell loses water the solution inside the cell becomes more
concentrated – water will move from a more dilute solution to a more concentrated
solution to even out the concentrations of the solutions on both sides of the cell
Fluid movement in plants – phloem carries food from leaves – xylem carries water and
minerals from the roots
when there is more water outside a root hair cell than inside water moves into the
cell by osmosis – it moves from cell to cell by osmosis to xylem tissue, which are like
straws – as more water enters the root hairs pressure is created pushing the water upwards
to stems and leaves
water is used in leaves for photosynthesis – leaves flat and thin to provide surface
area for sunlight and to diffuse gases into and out of cell through stomata – guard cells
open and close the stomata
as transpiration occurs through stomata this provides force to draw water up the
plant
plants use a pushing force from the roots and a pulling force from the leaves to
transport water up the plant
Topic 5 Cell Specialization and
Organization
Humans have about 100 different types of cells, each with its own function and structure – ex. nerve cells
have long fibres to carry signals, muscle cells are long so they can contract to do work, blood cells are
hollow disc shaped to increase surface area to pick up oxygen
Advantage of being unicellular – reproduce quickly
advantages of being multicellular – can grow large – don’t have to live in watery, food-rich environment –
can obtain energy from wide variety of foods – cells specialize and can do jobs more effectively
Cells of organisms are organized into tissues –
main types in animals – muscle – epithelial (skin and also covers internal structures such as
intestines) – connective (connects and supports ex. bone, blood – some are fibrous) - nerve
in plants – epidermal (skin) – xylem – phloem
several tissues working together form organs – ex. stomach, brain, eyes, lungs, heart, kidneys – in plants
(roots, stem, leaves)
organs work together to form systems – ex. circulatory, respiratory, digestive – in plants (root system, shoot
system and reproductive system)
RECENT ADDITION TO NOTES:
1. why does the body need oxygen? - oxygen is used in each of our cells to burn our fuel (food) to produce
energy
2. the pathway taken for carbon dioxide to exit the body from a cell in our hand
- the CO2 diffuses from the cell into a capillary, and then moves into a vein - the vein leads to the heart from there the CO2 moves into an artery to the lungs and again into a capillary so it can diffuse into the
alveoli - it moves into a bronchiole, a bronchus, the trachea and out through your nose or mouth
Topic 7 Body Systems and Your Health
High blood pressure (hypertension)
heart attacks, strokes
-test blood pressure to find:
blood volume
heart rate – if high builds blood pressure
artery size – if clogged harder for blood to move through
artery elasticity – if flexible can expand to let blood through – hardening of arteries
produces high blood pressure
blood viscosity – if thick flows less easily
disorders of circulatory system
cigarettes constrict vessels and CO competes with oxygen
poor diet – high salt raises blood pressure
_ cholesterol builds on walls of arteries, narrowing or blocking them – tiny
tears in walls cause blood clots – if travel to brain have stroke – restricted flow to heart,
heart attack
to avoid above - eat properly, exercise, don’t smoke
digestive system
carbohydrates – provide energy – sugar and starch – fruit, grains, beans, peas
fats – energy and cushion for internal organs – can be stored (great when we were–
cilia cells may die, mucus nomadic and did not have reliable food source; not so great
now)
proteins – growth and repair – meat, fish, eggs, certain plants
disorders of digestive system
low fibre diet – takes longer for colon to process – irritates colon wall – colon
cancer
stress, smoking, excessive alcohol – peptic ulcer
disorders of respiratory system
cigarette smoke and pollutants irritate cilia causing build-up of mucus on them –
cough to remove – lead to bronchitis - mucus producing cells multiply – narrow and
block airways – lead to emphysema
lung cancer – smoke damages lung tissue and causes cells to grow out of control