Characteristics of Living Things

Thinking Question…•…there are many characteristics that all

living things have in common. Name at least TWO things you believe all life has in common.

•Be prepared to share at least 1!

Biology Unit 1Intro to Biology

Intro Target 1I can identify and describe the following parts of every scientific experiment, including:

ControlIndependent VariableDependent VariableObservationInferenceLaw Theory

Remember from Physical Science…

•A hypothesis is a possible prediction (more than just a guess) about what will happen in an experiment.

•It is written as an if, then statement.

•Example: If I use a chemical fertilizer, then my plants will grow taller.

The “if” portion…•…refers to the independent variable!• It is what is changed in the setup of the

experiment.•Whatever “treatment” is used.•The one difference in the setup from group

to group.

• In our hypothesis: If I use a chemical fertilizer, then my plants will grow taller.

•So the chemical fertilizer is the independent variable!

The “then” portion…•…is the dependent variable!•It is what is measured in an experiment.•What change does the independent

variable cause?

•In our hypothesis: If I use a chemical fertilizer, then my plants will grow taller.

•So the height of the plants is the dependent variable.

Control Group

•In an experimental setup, the control group is the group that doesn’t receive the “treatment”

•It is used to compare (is my treatment making it better or worse than it would have been without the treatment?)

In an experiment for our hypothesis: If I use a chemical fertilizer, then my plants will grow taller.

•The control group would be the group of plants that didn’t get the chemical fertilizer.

•How do I know if fertilizer makes the plants grow taller if I don’t know how tall they would have gotten without any fertilizer?

Observations vs Inferences

•Observations consist of receiving knowledge of the outside world through our senses, our recording information using scientific tools and instruments.

•Inferences are ideas or conclusions that are drawn from evidence and reasoning, using prior knowledge and experiences to make conclusions based upon the observations made initially.

Theories and Laws

• A well tested explanation that unifies a broad range of observations is called a theory! A theory describes the process of how something happens.

• A theory may become the dominant view, but is not absolute truth and can be revised with more useful, more supported explanations.

• A law is what happens under certain conditions outlined in the law. A law does Not BEGIN as a theory!! A law describes the pattern of why something happens.

Time for a WS and some activities!Simpson’s Variables WS, Practice Identifying Variables WS, Magic Fishy Lab, Surface Tension of Water Lab

Learning Target 2 for Intro UnitI can name and describe at least five characteristics or themes of life that apply to all living organisms.

Characteristics

•There are many characteristics that all living things have in common.

•Here’s what we discussed based upon the characteristics discussed…!

Six Elements!•99% of every single

living thing is composed of these six elements:

•C (Carbon)•H (Hydrogen)•N (Nitrogen)•O (Oxygen)•P (Phosphorus)•S (Sulfur)• Just remember,

CHNOPS!

Composed of Cells•All living things are

made up of one or more cells.

•Example: All the living things you see around you are multicellular (composed of more than one cell); most of the things around you that you can’t see are unicellular (composed of only one cell).

Metabolism• All living things must use

energy to maintain their normal life functions.

• Example: living things that make their own energy (from the sun or from chemicals) are autotrophic; living things that can’t make their energy and therefore must consume other living things to meet their energy requirements are heterotrophic.

Water•Water is essential

for life. Almost all biochemical reactions occur with or in water.

•Living things are made up of mostly water. You and I are about 66% water!

Respond to Stimuli•All living things will

show a response to different stimuli.

•Example 1: A spider reacts to the movement made by a struggling insect in its web.

Example 2:Phototropism/Geotropism

•The leaves of the seedling grow upwards in response to light (phototropism)

•The roots of the seedling grow downwards in response to gravity (geotropism)

Example 3: Killdeer

•Do you know what unusual response it shows to an invader coming near its nest eggs?

•It pretends to have a broken wing, luring predators away from its nest. Then it flies away, returning to the nest at a later time.

Growth and Development

•All living things grow and develop.

•We often call this their Life Cycle.

•Growth occurs by cell enlargement and/or cell division.

Cottontail Rabbits

Reproduction

•All living things must reproduce to ensure the survival of the species.

Do you know what kind of turtle this is?

Snapping Turtle!

Do you know which one mates for life?

Canadian Goose!

Adaptations

•A physical trait or behavior that gives an organism an advantage in its environment.

What Ohio animal is this? What adaptations does it have?

Muskrat!

•Webbed feet•Thick fur•Tail is flattened

vertically

Evolution

•Living things go through changes which are passed on genetically to future generations.

Are the changes experienced by these goslings an example of evolution?

No! It’s an example of growth and development!

The State Fossil of Ohio!

•What is it?•Did this animal

experience significant changes over time?

•What happened to its kind (species)?

The State Fossil of Ohio!

•It’s a trilobite.•They did not

change much over millions of years.

•They are now completely extinct.

How many of the characteristics of living things can you remember without looking?!?

Themes of Life•Biologists use these characteristics to come

up with the 7 themes of life:1. Cellular Structure and Function2. Metabolism3. Homeostasis4. Reproduction5. Evolution6. Heredity7. Interdependence

The ones not discussed yet…

•There were three themes on the previous slide that we have yet to discuss.▫Homeostasis▫Heredity▫Ingterdependence

Homeostasis

• Homeostasis: maintaining a stable internal environment despite changes in the external environment.

Examples• Crocodiles sun themselves on

rocks in the morning to increase their body temperature since they are cold-blooded.

• Blood sugar levels – when your blood sugar is too high, it triggers your liver to work harder to process it; if your blood sugar is too low, your brain triggers your body to be “hungry”to increase it.

Heredity• Heredity: Traits are

passed from generation to generation.

Examples• A parent passes on

half of its genes to its offspring.

• This is why offspring will look similar to the parents.

Interdependence• Interdependence: Different species

are dependent on each other to survive.

Examples• Symbiosis is a great example of

interdependence. In symbiosis, different species are using each other to survive.

• Parasitism – when one species benefits and the other is harmed. (ex: tapeworm in intestines)

• Commensalism – when one species benefits and the other is neither harmed nor benefitted. (ex: barnacles on whales)

• Mutualism – when both species benefit; they are helping each other. (ex: flowers and their pollinators)

Stop Here!!

Intro Targets 3 and 4I can identify the parts of a microscope, and their functions.

I can use a microscope properly.

body tube

eyepiece (oculars)

revolving nosepiece

low power objective lens

medium power objective lenshigh power objective lens

stage clipsdiaphragm/condenserilluminator

arm

stage

coarse focus knob

fine focus knob

base

Time for some activities!How to Use a Microscope Online Lab, Introduction to the Microscope Lab