Stuff You Need to Know for Next Year

Characteristics of Life

Made of cells Able to reproduce Contains DNA Grows and develops Uses materials and energy Respond to their environment

Levels of Organization

Cells Tissues Organs Organ systems Organisms Population Community Ecosystem Biosphere

Getting Food

Autotrophs are organisms that can capture sunlight or energy to produce their own food. Also called producers.

Examples are plants, some algae, and some bacteria.

Autotrophs

Getting Food

Heterotrophs are organisms that rely on other organisms for their energy and food supply. Also called consumers.

Types of Heterotrophs

Herbivores obtain energy by eating only plants. Examples: cows, horses

Carnivores eat animals. Examples: snakes, owls

Omnivores eat both plants and animals. Examples: humans, bears

Detritivores feed on plant and animal remains and other dead matter. Example: snails, earthworms

Herbivores

Carnivores

Omnivores

Detritivores

Types of Heterotrophs

Decomposers break down organic materials.

Examples are fungi and bacteria.

Food Chains and Webs

A food chain is a series of steps in which organisms transfer energy by eating and being eaten.

A food web is a network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem.

Food Web

Ecological Pyramids

Ecological pyramids are used to show trophic levels in an ecosystem.

Energy Pyramid

An energy pyramid shows the relative amount of energy available at each trophic level.

Organisms use about 10% of this energy for life processes.

The rest is lost as heat.

Energy Pyramid

Biomass Pyramid

Biomass is the total mass of living organisms in a given area or ecosystem.

In a biomass pyramid, the greatest amount of biomass is at the base of the pyramid.

Biomass Pyramid

Pyramid of Numbers

A pyramid of numbers shows the relative number of individual organisms at each trophic level.

Pyramid of Numbers

Cycles in Nature

The water cycle is the process in which water moves between Earth’s surface and the atmosphere.

Water is returned to the atmosphere through evaporation and transpiration (plants).

Cycles in Nature

Carbon and oxygen are cycled through photosynthesis and respiration.

Carbon Cycle

Cycles in Nature

The nitrogen cycle is necessary for organisms to make amino acids and proteins.

Interactions Among Organisms

Competition occurs when organisms attempt to use a resource in the same place at the same time.

Predation is an interaction in which one organism (predator) captures and feeds on another organism (prey).

Predation

Interactions Among Organisms

Symbiosis is a relationship in which two species live closely together.

Mutualism is a relationship in which both species benefit. Ex: flower/insect

Commensalism is a relationship in which one species benefits and the other is not affected.

Symbiosis

Interactions Among Organisms

Parasitism occurs when one organism (parasite) lives on or inside another organism (host).

Ecological Succession

A series of predictable changes that occurs in a community over time.

Two Types of Succession

Primary succession takes place on an area that is originally completely empty of life.

Example of Primary Succession

In an area covered by lava, the first plants will be mosses that grow in cracks in the rock.

When they die, they will decompose and begin to form soil which will support grasses.

Eventually enough soil is formed to support small trees.

Primary Succession

Two Types of Succession

Secondary succession occurs in an area where life once existed but has since been destroyed.

For example, a forest that has been destroyed by a wildfire will contain no life. The first plants to grow will be weeds, followed by shrubs, pine trees, and hardwoods.

Secondary Succession

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Environmental Problems

Extinction occurs when a species disappears from all or part of its range.

Environmental Problems

Endangered species are species whose population size is declining in a way that places it in danger of extinction.

Endangered Species

Environmental Problems

Pollution is any potentially harmful substance added to an ecosystem.

Environmental Problems

Global warming is an increase in Earth’s average temperature caused by human activities adding carbon dioxide and other gases, such as methane, to the atmosphere.

Global Warming

Everything You Ever Wanted to Know About Cells

And Some You Didn’t.

Two Types of Cells

Prokaryotes are simple cells that do NOT have a nucleus or organelles. Ex: bacteria

Eukaryotes are cells that have a nucleus and organelles. Ex: plant and animal cells

ANIMAL CELL

BACTERIA CELL

ORGANELLES

An organelle is a structure within the cell with a specialized function.

Types of Organelles

1. nucleus- contains DNA and regulates cell activities

2. mitochondria- supplies the cell with energy through cellular respiration

3. ribosomes- produce proteins 4. Golgi apparatus (body)- processes and

packages proteins for export

More Types of Organelles

5. vacuoles- storage of water, food, wastes, etc.

6. cell membrane- provides protection and support and determines what enters and leaves the cell.

It is semi permeable. Some stuff gets in, and some stuff doesn’t.

THE CELL CYCLE

Cell Reproduction

Mitosis is the process in which a cell divides into two identical cells.

Somatic (body) cells reproduce this way.

Phases of Mitosis

1. prophase- DNA condenses to form chromosomes.

Phases of Mitosis

2. metaphase- chromosomes line up in the middle of the cell. Spindle fibers form.

Phases of Mitosis

3. anaphase- Spindle fibers pull chromosomes apart. Half moves into each

new cell.

Phases of Mitosis

4. telophase- chromosomes move to opposite sides and nuclear membranes

begin to form

cytokinesis- cytoplasm pinches in half. Each new cell has an identical set of

chromosomes from the parent

Interphase

Interphase- cell grows and develops and makes copies of DNA

Cancer

Cancer occurs when abnormal cells grow and undergo mitosis at an extremely rapid rate.

Genetics

Why You Look Like You Do

Gregor Mendel

Austrian monk Known as “the Father of Genetics” Performed experiments on pea plants

Alleles

An allele is two different forms of a gene that may be present on a chromosome.

A dominant allele will mask (cover up) the other.

Two recessive alleles must be present for it to be expressed.

Homos and Heteros

Homozygous means two alleles are the same. Ex: BB, tt

Heterozygous means two alleles are different. Ex: Bb, Tt

Genotype and Phenotype

Genotype is the genetic makeup of an organism. Ex: tt, Tt, TT

Phenotype is the physical expression of a trait (how an organism looks). Ex: short, tall

Generations

The parent generation is represented by the letter P.

The offspring of the parent generation are represented by F1.

The offspring of the F1 generation is F2.

Crosses

A monohybrid cross involves two individuals and a single trait.

Punnett Squares

If you cross a heterozygous tall plant (Tt) with a short plant (tt), what percent of the offspring will be tall?

Discovering DNA

James Watson and Francis Crick discovered the shape of the DNA molecule in 1953.

The shape is a double helix (twisted ladder).

Watson and Crick

DNA Shape

Structure

DNA contains sugar (deoxyribose), phosphates, and nitrogen bases.

Two Types of Bases: Purines: guanine and adenine Pyrimidines: thymine and

cytosine

Structure

Adenine pairs with thymine. Cytosine pairs with guanine.

DNA Structure

Selective Breeding

Selective breeding is the breeding of only organisms with desired traits to produced the next generation.

For example: horses, cattle, cats, dogs

Cloning

Dolly, a sheep, was the first mammal cloned from a somatic (body) cell.

The nucleus from an adult cell was transferred into an unfertilized egg that had its nucleus removed.

It was then implanted into another sheep.

Dolly

Karyotypes

A karyotype is an organized profile of a person’s chromosomes.

Chromosomes are arranged by size from largest to smallest.

Humans have 46 chromosomes. It can determine the cause of birth defects

or abnormalities.

Autosomes

Karyotype

Make a Karyotype

Down Syndrome

Sex Chromosomes

The 23rd pair of chromosomes determines a person’s sex.

Females have two X chromosomes. Males have one X chromosome and one Y

chromosome.

TO BE CONTINUED…