Science Tests and You: A series of information sheets designed to improve the
transmission of scientific knowledge.
Volume 3, Issue 1
In order to ensure success in the upcoming science test on Cells, you
should direct your review on the following areas. These can be found
throughout Unit 1 of your most excellent textbook: “Investigating Science
and Technology 8”.
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1.1
1.2
1.3
2.1
2.2
2.3
3.1
3.2
3.3
Living things and Cell Theory
Comparing Plant and Animal Cells
The Flow of Materials Into and Out of the Cells
Unicellular Organisms
Multicellular Organisms and Cell Specialization
Plant and Animal Cellular Processes
From Cells to Tissues to Organs
Interdependant Organ Systems
The Impact of Research in Cell Biology
Happy Studying
Definitions
Cell – The Cell is the basic structure nit of an organism and the building block of life.
Compound Light Microscope – Uses light focused through several different lenses
to form a magnified image of a specimen.
Cytoplasm – A jelly-like material in which the parts of the plant and animal cell float.
Cell Membrane – A thin covering that which keeps the cytoplasm together.
Organelles – Tiny parts within the cell that have special functions that help the cell
survive.
Membrane – A covering that holds individual organelles together, and also keeps the
different parts of the cell apart.
Micrographs – A photograph taken with a microscope.
Permeable – Water and air can pass through it easily
Impermeable – Water and air cannot pass through it.
Selectiviely Permiable – Refers to the property of a barrier that allows only certain
substances to pass through it.
Cellular Transport – The movement of substances into and out of the cell.
Diffusion – The movement of particles from an area of higher concentration to an
area of lower concentration.
Osmosis – A special kind of diffusion that involves only water through a selectively
permeable membrane.
Unicellular Organisms – living things made of a single cell.
Multicellular Organisms – rely on a variety of types of cells to perform specific
functions.
Cell specialization: Cells that come in a variety of shapes and sizes that are
designed to carry out a specific function.
Cellular Respiration – The process by which mitochondria provide energy for plant
and animal cells by transforming oxygen and sugar (food) into carbon dioxide and
water.
Photosynthesis – Process by which the chlorophyll in chloroplasts uses the Sun’s
energy to convert carbon dioxide and water in to sugar and oxygen.
Cell Division – Process by which a cell divides into two new cells.
Tissue: A group of cells that are similar in shape and function.
Organs: A groups of tissues that are organized into larger structures.
Organ Systems: Groups of organs that have related functions (eg. Excretory,
digestive, respiratory, endocrine, nervous, and circulatory)
Cancer – a disease related to the uncontrolled and rapid reproduction of cells
through cell division.
Tumor – A mass of cells that are continually reproducing but are otherwise nonfunctional.
Section Summaries
1.1
LIVING THING ANS CELL THEORY
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Living things are all shapes and sizes, but they are all made up of cells.
Cells were not seen until the end of the 13th century when lens makers became
more skilled at grinding lenses.
The earliest microscope was a tube with a single lens at one end and a plate at
the other. The magnification was 10X the actual size of the object.
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The Basic Ideas of Cell Theory
- The cell is the basic unit of life. The cell is the smallest living organism that
shows the characteristics of living things.
- An organism can be as simple as one cell (unicellular), life a paramecium, or
it can be made of of trillions of cells (multicellular), like an elephant.
- All cells are created from existing cells through a process called cell division
by which a cell divides into new cells.
1.2
Comparing Plant and Animal Cells
The difference between plant and animal cells is reflected in the structure of their
cells. The have similar specialized parts that do the same job, but the plant has some
unique parts that allow them to convert the Sun’s energy into food.
Make sure you study both of the illustrations on pages 18, 19 of the parts
and functions of the plant and animal cell.
In order to see cells and their parts better, they are stained before being placed under
a microscope. The most common stains for student purposes are:
- Food colouring which is non-toxic
- iodine, which is used to detect the presence of starch
- methylene blue, which is used on animal cells to make the nucleus visible.
1.3
The flow of Materials into and out of Cells.
Cell walls and membranes are selectively permeable to allow for the flow of materials
into and out of them (Cellular transport). Without this, cells would starve or
dehydrate.
See Diffusion and Osmosis definitions.
2.1
Unicellular Organisms
Unicellular organisms can live everywhere that can sustain life; in water, soil and in,
or on multicellular organsms. There are millions of species.
- Some are harmful (some bacteria), but they are essential for life on Earth.
- Phytoplankton provide most of the oxygen in Earth’s atmosphere and are the
foundation of the ocean food chain.
- Some bacteria are decomposers. They complete the cycling of matter by converting
nitrogen in soil into a form of nitrogen that can support plant life and the terrestrial
food chains.
- They move in different ways: Paramecium propel themselves with little hairs (called
cilia), E.Coli move by lashing a whip-like tail (a flagellum), an amoeba moves by
changing its shape and extending a pseudopod (false foot)
2.2
Multicellular Organisms and Cell Specialization
Multicellular organisms rely of specialized cells that perform specific functions. For
example: Specialized cells in a frog, including the eyes, muscles, and tongue, must
work in perfect coordination to capture an insect for food.
- Although the specialized cells have the same organelles as other plant or
animal cells, the organelles may be better adapted to performing the cell’s tasks.
- It is necessary to have many small cells instead of fewer large cells so that
material (water, food, oxygen) can be delivered within the cell over a shorter period
of time.
Specialized animal cells
- Skin cells – make up the largest organ in the human body
- Bone Cells – make up the structure that supports the body
- Muscle Cells – Have more mitochondria than other cells, so they can
transform more energy
- Nerve Cells – Transmit electrical impulses along the pathways to the brain
- Brain Cells – Receive and transmit electrical impulses
- Fat Cells – Store energy in the form of fat.
Specialized Plant cells
- Leaf cells contain chloroplasts, which convert the Sun’s energy into food
- Cell in a plant stem transport water and materials throughout the plant.
- Cell in a plant root – Absorb water and nutrients from the soil and transport
these resources to the stem.
2.3
Plant and Animal Cellular Processes
- All cellular processes such as growth, repair, and reproduction need energy.
Mitochondria provide energy for the cell through the process of cellular respiration.
- Plants produce energy through the process of photosynthesis.
- Cells have a lifespan. Human brain cells live between 30 and 50 years. Red blood
cells live for 120 days. Skin cells live for 20 days. Before they die, they create a
replacement for themselves through cell division.
Cell Division
- The cells nucleus splits in two.
- The membrane begins to pinch near the middle to divide the cytoplasm,
including its organelles.
- Then the cell splits into two.
3.1
From Cells to Tissues to Organs
Specialized cells that are similar in structure and function are grouped together
in tissues.
Organs are made up of tissues that work together to perform a specific task.
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Animal Tissues in Organs (4 types: Connective, Epithelial, Nervous, Muscle)
Connective Tissues supports and connects different parts of the body
Epithelial Tissues: Covers the surface of the body.
Nervous Tissues: Transmits and receives nerve impulses.
Muscle Tissues: Contracts to cause motion.
Plant Tissues in Organs (3 types: protective, photosynthetic, and transport)
- Protective: Form a covering on most plants that helps prevent water loss.
- Photosynthetic: Transform the Sun’s energy into sugar
- Transport: Contains hollow, tube-like cells that move food and water through
the plant.
3.2 Interdependant Organ Systems
Please read and understand the function of each of the HUMAN
ORGAN SYSTEMS
- A plant has two types of organ systems (root system and shoot system)
Skeletal, muscular, circulatory, respiratory, nervous, digestive, excretory,
integumentary, endocrine, lymphatic, reproductive.
1.3
The Impact of Research in Cell Biology
As we understand more about cellular processes, we are able to conduct research in
cell biology in a variety of areas. These include:
Stopping to development of cancers
Regenerate nerve cells to repair spinal cord injuries
Develop vaccines to prevent disease
Discover biological tools to clean up pollution
Prepare to stop infectious diseases not yet known
Increase world food production.