Transcript biology-unit-1 - Churchill High School


An unmanned space
probe was sent to
Mars to check for
signs of life on the
planet. How could
such a probe confirm
the existence of life?
Unit One: The Nature
of Life
BIOLOGY

It is the study of living
things
Characteristics of Life

Each living thing is called an organism

Organisms have the following characteristics:

1) Living things are highly organized and contain
many complex chemical substances

2) Living things are made up of one or more cells,
which are the smallest units that can be said to be
alive

Organisms cont’d

Living things use energy

Living things have a definite form and a limited
size

Living things have a limited life span

Living things grow
Organisms cont’d

Living things respond to changes in the
environment

Living things are able to reproduce

Groups of living things evolve, or change, over
time

Non-living objects may show one or a few of
these characteristics but never all

There are some “borderline” cases:
Viruses- can be stored like chemicals in a bottles
but when inside living cells, they will reproduce
(but they still don’t have all the characteristics of
living things)

Life Processes

Living things carry out many different kinds of
processes








Nutrition
Transport
Respiration
Synthesis and Assimilation
Growth
Excretion
Regulation
Reproduction

Many of these life processes are required for
maintaining a constant environment within an
organism despite its changing external
environment

The condition of a constant internal
environment is known as homeostasis
Nutrition




All organisms take materials from its external
environment and changes it into a more
usable form
Nutrients are the substances that an
organism needs for energy, growth, repair or
maintenance
Taking in food from the environment is
ingestion
Digestion is the breakdown of food materials
into simpler forms
Transport

This is the process by which substances
enter and leave cells and become distributed
within the cells

Transport varies between single celled
organisms and multi-cellular organisms

Ex. Circulatory system in humans
Respiration

All life processes require a constant supply of
energy

Respiration deals with energy released within
cells

This may or may not involve breathing
Synthesis and Assimilation




Synthesis is when organisms are able to
combine simple substances chemically to
form more complex substances
Synthesis produces materials that can
become part of the structure of an organism
It also allows the organism to `grow
The incorporation of materials into the
organism’s body is called assimilation
Growth

Growth is the process by which living
organisms increase in size

This is one of the results of the assimilation of
nutrients

Growth in animals usually follows a pattern
and will end

Some plants will continuously grow
Excretion

All organisms produce waste

Waste, if accumulated, can be harmful to the
body

Removal of wastes is excretion
Regulation

All activities that help to maintain an
organism’s homeostasis make up the
process of regulation

Ex. Digestive system

Ex. Nervous system

Ex. Excretory system
Reproduction


This is the process by which living things
produce new organisms of their own kind
2 types:

Asexual (single individual produces offspring
identical to the parent)

Sexual (2 parents and offspring are not identical
to either parent)
Metabolism

All the chemical reactions occurring within the
cells of an organism are called its metabolism

This includes processes that build up
complex substances from simpler ones and
breaks down complex substances into
simpler ones
Questions

How are humans and crystals, such as those
that form on a window, alike in terms of their
signs of life? How are they different?

Looking at the pictures shown previously, list
all the characteristics that prove an organism
is living. (rock, plant, mouse, paramecium,
dead tree, cockroach, kitten)
Questions

List 4 ways in which a car is like a living thing.
List 4 ways a car is not a living thing.
In PAIRS ONLY- create a mnemonic device
that will help you remember all 9 life
processes
Ex. Planets- My Very Eager Mother Just
Served Us Nachos
