MCAS Review2012

Chemistry of Life

Define Organic

Compounds that contain carbon atoms that are covalently bonded to other elements, typically hydrogen, oxygen, and other carbon atoms

C-H-O

All living things are made up of 6 essential elements: SPONCH

Name the 6 elements of life:

Sulfur

Phosphorus

Oxygen

Nitrogen

Carbon

Hydrogen

Elements join together by chemical bonds to form compounds. Name the 3 types of chemical bonds

Covalent Bonds

Ionic Bonds

Hydrogen Bonds

There are 4 major categories of organic molecules that are made up of the SPONCH elements.

Lipids

Carbohydrates

Proteins

Nucleic Acids

Lipids

Elements:

Structure:

Function:

Examples:

Carbon, Hydrogen, Oxygen

3 fatty acid chains linked by a glycerol backbone

Building blocks of the cell membrane, energy storing molecules

Steroids like cholesterol & fats

Carbohydrates

Elements:

Structure:

Function:

Examples:

Carbon, Hydrogen, Oxygen

Monosaccharides bonded together in long chains (poly)

Key source of energy!

Sugar and starch

Proteins

Elements:

Structure:

Function:

Examples:

Carbon, Hydrogen, Oxygen, & Nitrogen

Amino acids bonded in long chains that coil around each other into specific shapes

Enzymes (speed up reactions), structural (hair, muscle, skin, etc), antibodies (protect body)

Enzymes, collagen, antibodies

Nucleic Acids

Elements:

Structure:

Function:

Examples:

Carbon, Hydrogen, Oxygen, Nitrogen & Phosphorus

Long chain of nucleotides bonded together

DNA (store genetic info), and RNA (aid in building proteins)

DNA, RNA

Define Chemical Reaction:

The process during which chemical bonds between atoms are broken and new ones are formed, producing one or more different substances

AB + CD AC +BD

Write an example of a chemical reaction and label the reactants and products:

NaCl Na+ + Cl-

Reactant Products

Define Activation Energy

The energy needed to start a chemical reaction

Define Enzyme:

Proteins that increase the speed of a chemical reaction

Any factors that affect the shape of an enzyme affect the enzyme’s activity.

What effect does pH and temperature have on an enzyme’s function?

pH and temp must be within an optimal range for an enzyme to do its job

If pH and/or temp are not in the proper range then the enzyme may change shape or become inactive

Cell Biology

Draw a Plant Cell

Draw an Animal Cell

Complete the Table:

Cell Part Function (job) Plant/Animal/Both

Plasma Membrane

Encloses the cell & separates the cytoplasm from its surroundings, regulates what enters & leaves the cell

Both

Nuclear Envelope

Separates the nucleus from the cytoplasm

Both

Nucleus Stores DNA and makes mRNA Both

Nucleolus Located inside the nucleus, mRNA is made here

Both

Complete the Table:

Cell Part Function (job) Plant/Animal/Both

Cytoplasm Interior part of the cell made up of fluid that cushions all organelles

Both

Mitochondria Provide energy to the cell Both

Endoplasmic reticulum

Process & modify proteins that were made in the nucleolus

Both

Golgi apparatus

Package proteins into vesicles for export throughout the cell

Both

Complete the Table:

Cell Part Function (job) Plant/Animal/Both

Lysosome Contain digestive enzymes to clean up the cell

Both

Ribosome Aid in protein synthesis Both

Vacuole Help digestion of materials, store nutrients & keep cell pressure

Plant

Cell Wall Support & maintain shape, protect cell from damage, connect to nearby cells

Plant

Complete the Table:

Cell Part Function (job) Plant/Animal/Both

Chloroplast Use light energy to make food (carbohydrates) through photosynthesis

Plant

Cytoskeleton Help to maintain cell shape & aids in movement of materials in the cell

Both

Centriole Help the formation of the spindle to move chromosomes during mitosis

Animal

Prokaryote vs. Eukaryote

Prokaryote

No nucleus

No organelles

Reproduce asexually

Small

Example: bacteria

Eukaryote

True nucleus

Organelles

Reproduce either sexually or asexually

Larger

Example: plant, animal, protist, fungi cells

Draw the structure of the cell membrane:

Image source: library.thinkquest.org

What is it called?

Phospholipid bilayer

Diffusion, Osmosis, & Facilitated Diffusion

Diffusion –

Osmosis –

Facilitated Diffusion -

Passive transport across a membrane from an area of high concentration to low concentration (downstream)**Does not require energy

Diffusion of Water**Does not require energy

Passive transport across a membrane from an area of high concentration to low concentration that requires carrier proteins**Does not require energy

What are the 6 Kingdoms of Life?

Eubacteria

Archaebacteria

Protista

Fungi

Plants

Animals

Identify the formulas:

6H20 + 6CO2 -> C6H12O6 + 6O2

C6H12O6 + 6O2 -> 6H20 + 6CO2 + energy

Photosynthesis

Cellular Respiration

Define Photosynthesis

The process that captures the sunlight’s energy in the chloroplast of plant cells and converts it to glucose (sugar), the food for life

Define Cellular Respiration

The process that breaks down glucose to make energy for the cells to use

How are Photosynthesis & Cellular Respiration related?

They are opposites!

One makes sugar (photosynthesis)

One breaks sugar (respiration)

Humans need oxygen to be able to perform cellular respiration and gain ATP energy.

What would happen to the oxygen levels on Earth if photosynthesis stopped?

Oxygen

What happens when a phosphate group is removed from ATP?

Energy is released for the cell to use!

Compare the energy levels of ATP, ADP, and AMP to the energy levels of a battery

ATP (Adenosine Triphosphate) is like a fully charged battery with 3 phosphates

ADP (Adenosine Diphosphate) is like a partially charged battery with 2 phosphates

AMP (Adenosine Monophosphate) is like a dead battery with only 1 phosphate

Draw and label the phases of the cell cycle:

What is the function of the cell cycle?

To successfully make new cells for growth of the organisms or replacement of dead or damaged cells

Compare and contrast mitosis and meiosis

Describe fertilization using haploid, gamete, diploid, and zygote

Genetics

What is DNA?

Deoxyribonucleic acid

The material that stores the information that determines an organism’s characteristics (traits)

Draw and Label a Nucleotide

How do nucleotides form the structure of DNA? Nucleotides link

together to form a chain

Corresponding nucleotides match-up according to the base-pairing rules to form the second chain

Draw a molecule of DNA

Sugar/Phosphate backbone

Nucleotide

Nitrogen bases

Hydrogen bonds

What is a double helix?

2 strands of nucleotides attached by hydrogen bonds in the middle and twisted together

Base-pairing Rules:

Adenine – Thymine

Guanine - Cytosine

What is the relationship between Gene and DNA?

Genes are sections of DNA that code for proteins

The rest of the DNA codes for nothing!

3 Steps of DNA Replication:

1. DNA helicase unwinds the double helix by breaking the hydrogen bonds, forming the replication fork

2. DNA polymerase adds complementary nucleotides to the separated DNA strands

3. DNA polymerase continues until it reaches the end of the molecule, forming 2 identical DNA molecules

Gene expression is the process of turning the genes in the DNA into a phenotype that can be seen

Draw and label the 2 phases of gene expression, and where they happen in the cell

End Products

Replication Transcription Translation

Start DNA DNA RNA

End DNA RNA Protein

Types of DNA Mutations:

What will happen if there is a mutation in a gamete?

Gametes are egg and sperm cells

A mutation would result in a genetic disorder or failure to fertilize (no zygote)

Two parents are heterozygous for brown eyes Bb x Bb

B b

B BB Bb

b Bb bb

Genotype Ratio:1BB:2Bb:1bb

Phenotype Ratio:3 Brown:1 Blue

What Percent of the Offspring have Blue Eyes?

25%

Why do men experience male-pattern baldness more than women?

The trait is sex-linked

Men only have one X chromosome, so whatever allele they get for hair, whether it is the dominant normal or the recessive allele that causes baldness, it will show.

Men have XY and women have XX

Using Mendel’s laws of segregation and independent assortment, explain why not all tall people have brown hair. The law of segregation says that during

meiosis the alleles separate independently during Metaphase II of meiosis

The law of independent assortment says that homologous chromosomes separate independently during Metaphase I of meiosis

The two traits are chosen randomly

Describe an example for each of the following:Codominance – Polygenic traits -

Incomplete dominance – Multiple alleles -

Both forms of the trait are displayed – dalmation dog with black spots

Several genes control one trait – skin color or hair color

Neither allele for the trait is dominant – white flower X red flower = pink!

More than 2 alleles for one trait – Blood types A, B, AB, O

Anatomy & Physiology

Describe the 4 levels of structural organization in the human body

Cells

Tissues

Organs

Organ Systems

Digestive System

Function Path of Food (all major organs)

Important Digestive Enzymes

Breaks down and absorbs nutrients from food; removes waste; maintains water balance

Mouth – pharynx – epiglottis – Esophagus – stomach – small intestine – large intestine – rectum – anus

Amylase – in saliva, breaks down sugar

Pepsin – in stomach, breaks down protein

Lipase – in pancreas, breaks down fat

Circulatory System

Function Path of Blood (all major organs)

Transports nutrients, wastes, hormones, and gases

Capillary drops off nutrients to cell & picks up waste – venule – vein – right atrium – right ventricle – pulmonary artery – capillaries (lungs) – pulmonary vein – left atrium – right atrium – aorta – artery – arteriole - capillary

Excretory System

Function of Kidneys Function of Liver

Regulate the amount of water and salts in the blood

Secretes bile which helps break down fats and absorb vitamins; regulates sugar levels in blood

Respiratory System

Function Path of oxygen/carbon dioxide (all major organs)

Move air into and out of lungs; controls gas exchange between blood and lungs

Mouth/nose – pharynx – epiglottis – larynx – trachea – bronchi – bronchioles – alveoli – bronchioles – bronchi – trachea – larynx – epiglottis – pharynx – mouth/nose

Nervous System

Function Basic Unit – The Neuron (How it Works)

Major Components

Regulates behavior; maintains homeostasis; regulates other organ systems; controls sensory and motor functions

Neuron is made up of dendrites that receive an electrical signal which is then carried to the cell body which is then carried through the axon and is then passed on to the next neurons dendrites

Peripheral NS – sensory & motor neurons

Central NS – brain & spinal chord

Muscular/Skeletal System

Function of Muscles 2 functions of bones

Help in movement of bones; contraction of heart and other organs

Provide shape and support to the bodyProduce blood cells and platelets in the marrow of the bone

3 types of muscle tissue

Skeletal – muscles that move bones

Smooth – involuntarily controlled; the muscles that cause the stomach to contract

Cardiac – involuntarily controlled; is the muscle that makes up the heart

2 Types of Connective Tissue

Ligament – attaches bone to bone

Tendon – attaches muscle to bone

Define homeostasis

The process of maintaining internal stability within an organism

Explain how body temp is maintained When it is cold out, the sensory neurons (nervous

system) send a signal to the spinal cord then the brain

The brain interprets the signal and sends a message to the motor neurons

The motor neurons trigger the muscles in your body to contract/relax over and over, which causes the bones to move

This increases warmth in the body

The heart also beats faster sending warm blood more quickly throughout the body to increase warmth

Evolution & Biodiversity

What is Evolution by Natural Selection? Evolution is the change of a species over time

This happens due to some kind of change in the environment of an organism. It must adapt or die

If there is a mutation or trait that is advantageous, it will be selected for (natural selection)

Organisms with the advantageous trait are picked as mates and reproduce more successfully, passing on the good genes

Over time, the build-up of differences is called evolution

Example:

Evidence for Evolution

Fossil Record

Comparative Anatomy Genetic & molecular similarities

Homologous Structures

Vestigial Structures

Bones from Lucy show a relationship between apes and humans

The forearm of penguin, human, lizard, and bats all have the same bones

Whale used to be a 4-legged animal on land and then moved into the sea and evolved so that the pelvis and legs have lost their function

Gorilla and human have an almost identical hemoglobin protein in the blood

Speciation

Mutation – elephant with NO tusks

Reproductive Isolation – does not get hunted by poachers and lives freely

Natural Selection – live longer since they are not hunted and are selected by other elephants

Divergence – over time if populations stay separated they may continually adapt and develop more and more genetic differences

New Species – if the 2 populations become so genetically different that they no longer breed successfully, they are considered 2 species

Define Species:

The basic classification of living things

What characteristics are organisms classified (or grouped) by?

Form and structure

Behavior

Molecular similarities

8 Levels of Classification

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species

Binomial Nomenclature Rules:

The first word is the Genus name and is capitalized

The second word is the species and is lowercase

Humans = Homo sapiens

Define Biodiversity

The variety of organisms, their genetic differences, and the communities and ecosystems in which they occur

How does evolution affect biodiversity?

Evolution by natural selection offers a means by which organisms can become more and more different over time to a point where they become new species.

Every living thing experiences evolution at some speed

The large biodiversity of life on Earth can be attributed to the process of evolution

Ecology

What is Ecology?

The study of interaction of living organisms with one another and with their physical environment

What are the components of an ecosystem?

Biotic factors (living) – plants, animals, bacteria, fungi

Abiotic factors (non-living) – soil, water, weather, climate

Define Community

All the living things in one ecosystem

Flow of energy

Energy begins with the producers who take the sun’s energy and turn it into food

Primary consumers (herbivores) obtain their energy by eating the producers

Energy moves to the secondary consumers (omnivores/carnivores) who obtain their energy by eating the herbivores

Lastly, when all organisms die, decomposers obtain their energy and recycle it back into the ecosystem

What does a food chain show?

The path of energy flow in a specific ecosystem

Grass -> Rabbit -> Fox -> Wolf

How do food chains relate to food webs?

A food web is made up of many interconnected food chains

Why are energy pyramids usually no more than 4 trophic levels?

As you go up the trophic levels in an energy pyramid, energy is lost as heat from the organisms that are not eaten (die)

Once you reach the top there is very little energy available

DecomposersDecomposers belong anywhere outside the pyramid. This is because of their niche. Decomposers niche in an ecosystem is to obtain energy from any dead organism and then to recycle the nutrients back into the ecosystem

Water Cycle

Water starts in the nonliving as vapor in the atmosphere (clouds) then falls as rain, goes into soil, is taken up by the roots of plants (now part of the living) and then transpired back into the atmosphere

Carbon Cycle

Carbon in form of carbon dioxide

(CO2)

PhotosynthesisCellular Respiration

Carbon in form of food and living

things

Nitrogen Cycle

Nitrogen in the non-usable form of

nitrogen gas

Nitrogen-fixing bacteria

Denitrifying bacteria

Nitrogen in the usable form of nitrates and

ammonia

Biological Communities

CommensalismInteraction between 2 organisms where 1 benefits and the other is neither helped nor harmed

CompetitionWhen 2 organisms use the same resources and there is a struggle to obtain the resources

ParasitismInteraction between 2 organisms where 1 benefits and the other is harmed

MutualismInteraction between 2 organisms where both benefit

Predator/PreyInteraction between 2 organisms where the predator needs to hunt and kill the prey for food/energy in order to survive

Define Population

A group of organisms of the same species living in one area

Factors that affect population size and biodiversity:

Climate change

Loss of resources

Changes in symbiotic relationships

Pollution due to human activity

Good Luck on the MCAS Biology Exam!You can do it!