The Living Environment

Regents Review

Topic 1: Similarities & Differences Among Living Organisms

Organelle Function Human System

Nucleus Control center Nervous & endocrine

Mitochondria Aerobic respiration Circulatory, digestive, respiratory

Ribosome Protein synthesis Digestive, circulatory

Cytoplasm Holds organelles, transport

Circulatory

Vacuole Storage of wastes Excretory

Lysosome Intracellular digestion Digestive, immune

Cell membrane Regulates passage of substances in and out of cell

Immune system

Topic 1 cont’d Transport

Cell membrane is a lipid bilayer (two layers of lipids with proteins in between- some acting as channels and receptors)

Concentration gradient (when a difference in the amount of a particular substance exists across a barrier such as the cell membrane)

Passive transport (diffusion)- substances move along concentration gradient (from high concentration to low) WITHOUT the use of energy

Ie. O2,, CO2 & H2O (osmosis) Saline solution (water moves out of cells dehydrate) Distilled water (water moves into the cells swell & potentially

burst) Active transport- substances move against concentration gradient

WITH the use of energy in the form of ATP Na+ and K+ are kept at high levels in and out of the cell to

maintain a gradient for nerve impulses (sodium/potassium pump)

Osmosis

Red onion cells in concentrated salt solution (osmosis out of cell)

Red onion cells in distilled (100% water) (osmosis into the cell)

Topic 1 cont’d Cell receptors

Extend off of cell membrane Have a specific shape Only recognize certain substances to

allow in or out of the cell Neurons (nerve cells) have receptors

for specific chemicals (neurotransmitters)

Certain cells have receptors for certain hormones as the hormones travel throughout the circulatory system to reach target cells

Antibodies Proteins produced by B cells in

immune system (white blood cells) Specific in shape for particular

pathogens They isolate pathogens for

destruction by other white blood cells

Topic 2: Homeostasis in Organisms

Process Location Raw materials

Products Role in homeostasis

Photosynthesis chloroplast

CO2 & H2O Glucose,O2, & H20

Provides food (simple sugars) for producers

Respiration mitochondria

Glucose & O2 (aerobic)

ATP, CO2

& H2O

Releases energy from chemical bonds of glucose to the usuable form of ATP

Topic 2 cont’d Enzymes:

Proteins Specific shape so that they

only fit with a certain substrate

Enable (allow) reactions to occur faster and with less energy (organic catalysts)

Have optimal pH and temperature (if outside of optimal range the enzyme can be denatured (change shape) and be unable to function properly

Topic 2 cont’d Feedback mechanisms

Most common type in the human body is negative feedback Something is off unless activated, once its job is completed

it is deactivated Comparable to a thermostat (it only signals the oil burner

to turn on when the temperature drops below predetermined level- once temp. is restored a signal is sent to turn off the oil burner)

Our hormones typically work in this fashion Insulin is produced by the pancreas in response to an increase in

blood sugar levels the sugar is taken in by the liver and converted to the

polysaccharide glycogen once levels are low enough a signal is sent to the liver to stop

insulin production

Topic 2 cont’d Guard cells and feedback:

Guard cells are specialized cells found mainly in the lower epidermis of a leaf

They regulate an opening called a stomate, which allows gases such as CO2, H2O & O2 in and out as needed by the plant

The guard cells keep the stomate closed unless the plant needs gases to enter or leave

Guard cells w/ open stomate (top view)

Cross section of leaf epidermis w/ guard cells & stomate

Topic 3: Genetic Continuity DNA= deoxyribonucleic acid

Nucleic acid Double helix Building blocks = nucleotides

Sugar (deoxyribose) Phosphate Nitrogen base (A,T,C,G)

A-T & C-G RNA = ribonucleic acid

Nucleic acid Single stranded Building blocks = nucleotides

Sugar (ribose) Phosphate Nitrogen base (A,U,C,G)

Topic 3 cont’d DNA replication

Unwinds Unzips between bases Two identical molecules are created Occurs prior to mitosis

Protein synthesis DNA has instructions for a particular protein The portion needed unwinds and unzips mRNA is created from the DNA template to carry code from nucleus to

ribosome (transcription) At the ribosome the mRNA is read in groups of three bases (codons) tRNA delivers the appropriate amino acids over to the codons on

mRNA and then leaves Peptide bonds join the amino acids together to create a polypeptide

(protein)

Topic 3 cont’d Genetic engineering:

Gene splicing- restriction enzymes used to cut out desired gene from DNA

Desired gene from one organism is inserted into the DNA of another organism

The gene for human insulin has been successfully inserted into a plasmid (circular portion of DNA) of bacteria bacteria produce human insulin and pass this trait onto their offspring

Genes for herbicide resistance, frost resistance, nutrient content etc. have been inserted into plant DNA (crops such as corn, rice, tomatoes)

Chromatography Gel Electrophoresis

Topic 3 cont’d Selective breeding:

Farmers have been doing this for years

Select seeds from desirable plants (biggest corn, juicy tomato etc.) and only grow the seeds from those plants

This is also done with livestock, racehorses and dogs

Certain individuals are chosen to mate so that their desirable traits are passed on to offspring

Decreases biodiversity Recessive traits (such as

diseases) can become more prominent

Topic 4: Reproduction & Development

Meiosis – cuts chromosome number in half in the creation of gametes (egg and sperm- contain monoploid/haploid (n) amount of chromosomes)

Crossing over and genetic shuffling increase variety in gametes

Meiosis occurs in the gonads or sex organs (ovaries & testes)

Fertilization is the union of egg and sperm to restore diploid number (2n) of chromosomes to create a zygote

Cleavage or mitosis in a zygote increases the number of identical cells

Stages of cleavage

Topic 4 cont’d Differentiation is the process by which cells are given specific

instructions through the activation of certain portions of their genetic code

Fertilization occurs in the fallopian tube of a human female (oviduct)

The zygote implants in the uterus and a placenta develops from the uterine wall for the transport of nutrients and wastes between mother and fetus

Feedback is involved in regulating the menstrual cycle involving the pituitary gland in the brain, the ovary and the uterus

Topic 4 cont’d Reproductive technology:

IVF- egg and sperm are harvested from parents and united in a petri dish

Cloning- a nucleus from a body cell of the organism to be cloned is put into an empty egg

The egg with the transplanted nucleus is treated with growth factors

When the zygote has divided (morula stage) it is put in a surrogate for gestation

Screening: Amniocentesis- amniotic fluid is sampled to screen for genetic

disorders Karyotype- chromosomes in amniotic fluid are harvested and

arranged in order from # 1 – 23 to screen for chromosomal disorders such as Down Syndrome

Ultrasound

Normal Karyotype

Karyotype of Individual withDown Syndrome

Topic 4 cont’d Mitosis: involved in asexual reproduction

IPMAT: Interphase- majority of the lifespan of a cell (all life

functions and chromosomes replicate) Prophase- chromosomes become visible and nuclear

membrane begins to break down Metaphase- double-stranded chromosomes line up at

the middle Anaphase- chromatids separate toward poles of the cell Telophase- nuclear membrane reappears around each set

of chromosomes and the cell membrane begins to pinch in (or in a plant cell a cell plate forms from the inside out)

Topic 4 cont’d

Types of asexual reproduction: Binary fission (equal cytoplasmic division)- bacteria Budding (unequal cytoplasmic division) – yeast

(unicellular) and hydra (multicellular) Vegetative propagation – part of a plant is used to grow an

exact copy of that plant (leaves, stems etc.) Regeneration – a part of the organism can be replaced or an

entire organism can be created from that piece (starfish, lizard tail)

Budding in yeast

Unicellular Bud

Multicellular bud

Budding in hydra

Topic 5: Evolution Natural selection (Charles Darwin)

Overproduction = more offspring produced than can possibly survive

Competition (struggle for survival)- there are limited resources

Variation- some will have a particular trait or set of traits that are favorable while others will not

Survival of the fittest- those with the favorable trait will be more likely to survive reproduce and pass the trait on to their offspring

** Over time the population SHIFTS to CONSIST of mostly those with the favorable trait (DO NOT SAY BECOME RESISTENT ETC.!!!!!!!)**

Topic 5 cont’d Evidence of evolution:

Homologous structures – similar in origin and layout but may be different in function and appearance (suggest a common ancestor)

Comparative embryology, cytology and biochemistry are all types of molecular evidence based on DNA and are therefore more reliable than physical evidence

Topic 5 cont’d Adaptations = favorable traits for a particular

environment at a particular time that increase chances of survival

Selecting agents (an environmental factor such as food source that determines which traits in a population are favorable)

Speciation – creation of a new species as the result of accumulating enough different adaptations from the main population to be able to successfully reproduce fertile offspring Reproductive and geographical isolation contribute to this Adaptive radiation – development of several new species

from a single common ancestor (finches)

Variation in shell coloration/pattern

Overproduction of clownfish eggs

Topic 6: Ecology

Levels of organization: Biosphere biomesecosystemcommunitypopulation (greatest

biodiversity to least amount of biodiversity) Abiotic = all nonliving factors in an ecosystem (ie. Carbon

dioxide, water, sunlight, temperature, pH) Biotic= all living factors in an ecosystem (algae, trees, frogs,

minnows, foxes, sharks etc.) Food webs provide illustrations of all possible pathways of

energy/nutritional relationships in an ecosystem (more stable) Food chains indicate one pathway of energy/nutritional

relationships in an ecosystem

Topic 6 cont’d

Producers are always found at the base in an ecosystem/foodweb/foodchain/food pyramid because they contain the most available energy

Energy CANNOT be recycled in an ecosystem and must be constantly SUPPLIED for it to remain stable

Materials such as carbon dioxide, water, oxygen, nitrogen must be RECYCLED by decomposers such as bacteria and fungi for an ecosystem to remain stable

Topic 6 cont’d Nutritional Relationships/trophic levels

Producers/autotrophs convert light energy into chemical energy in organic compounds (glucose)- a.k.a- make their own food (inorganic raw materials organic product)

Primary consumers (herbivores)- consume only producers Secondary consumers (can be omnivores or carnivores)-

consumer other consumers and sometimes some producers Teriary consumers (typically carnivores) consume

primarily other consumers Scavengers consume dead organisms (turkey vultures,

hyenas, raccoons) Decomposers break the remains of dead organisms (and

their wastes) down to recycle their nutrients back into the ecosystem

Topic 6 cont’d

Symbiotic relationships: Mutualism (both benefit: +,+) (ie. Remora

cleaning parasites off of a shark) Parasitism (one harmed, one benefits: -,+) (ie.

Ticks and dogs, tapeworm and human) Commensalism (one benefits, one unaffected: +,0)(best example is barnacles on a whale)**Predator/prey is NOT a symbiotic relationship

because it is short term- once the prey is caught the relationship is over

Barnacles on a whale A remora and a shark

Tick on a dog

Topic 6 cont’d A habitat is where an organism lives and its niche is its role in that habitat

(ie. What it consumes) Competition results over limited resources as there can only be one species

per niche in an ecosystem Limiting factors help keep populations in an ecosystem in check: ie.

Predators keep their prey populations in check and visa versa, light intensity controls where plants can grow, temperature, pH (they can be biotic or abiotic)

Carrying capacity = the amount of a particular population that can be maintained indefinitely in an ecosystem (determined by limiting factors)

Ecological succession (due to natural disaster such as a volcanic eruption or forest fire)

Pioneer organisms are the first to show up and can survive harsh conditions (ie. Lichens, grasses, mosses)

Climax community is the final, stable, self-sustaining stage that can last until a major disruption

Each stage paves the way for the next, making them self-sacrificing

Carrying Capacity Graphs

Topic 7: Human Impact

Global Warming Cause- excess greenhouse gases in atmosphere trap heat Carbon dioxide is the most common greenhouse gas

released Burning fossil fuels and deforestation are two major

sources of increased atmospheric carbon dioxide Cleaner fuel sources such as solar power, wind etc. are

ways to reduce greenhouse gas emissions Reforestation is another way as trees take in CO2 from the

atmosphere for photosynthesis Burning fossil fuels also releases sulfur dioxide which can

cause acid rain!

Topic 7 cont’d Ozone depletion:

Cause is CFCs from coolants in refrigerators, ACs, and in aerosols

Montreal Protocol banned CFCs however older appliances if disposed of improperly can release CFCs into the environment

Not all countries adhere to this ban, thus some CFCs are still used in products globally

The ozone protects organisms from more harmful UV rays getting through, but the thinner it is the more rays can enter, increasing the incidence of skin cancer

Laws must be enforced globally banning CFCs and there must be stricter penalties for improper disposal

Topic 7 cont’d Biological Controls:

Pesticides can harm species other than those that are being targeted

Biological controls are natural remedies for pest control and include natural predators of pest species and sterilizing individuals to prevent reproduction

Advantages = target pest populations only, can be cheaper Disadvantages= the natural predators may begin to

consume native species or compete for a niche with a native species

Biomagnification = greater quantities of pollutants are found in top level consumers as each successive level consumes more of the previous level (ie. DDT still found in fatty tissue of humans)

Topic 7 cont’d

Deforestation Leads to loss of habitat Decreases biodiversity Medicines and other medical advancements may

go undiscovered Increases carbon dioxide in atmosphere as there

are less trees to take it in for photosynthesis Stricter laws should be passed to limit and

reforestation can reverse the effects as long as it is done at a rate to compensate

Topics 8&9: Lab Skills and Scientific Method

Scientific Method- Problem: Phrased as a question

Ie. How does pH affect petal color? Hypothesis: Phrased as a statement

Ie. It is hypothesized that an acidic pH will produce flowers with red petals, while a basic pH will produce flowers with white petals

Design a controlled experiment: Only one variable (ie. pH level) = INDEPENDENT DEPENDENT VARIABLE relies on independent ie. Growth relies

on or depends on the pH, temperature, amount of sunlight etc. Other factors remain the same (constants) (ie. Plant species,

amount of water, sunlight, temperature) Collect measurable data (ie. Number of plants with red petals and

number of plants with white petals in each group)

Topics 8&9 cont’d Organize data into a table with headings and units and create an

appropriate graph with an even scale and labels Large sample size (the more specimens in each group the more

reliable the data- accounts for variety) Draw a conclusion (state whether or not the hypothesis was

supported and provide data from the experiment to support) (ie. Out of 50 plants in the acidic pH 45 of them had red petals, while in the basic pH 49 of the 50 plants had white petals, therefore the hypothesis that flowers grown in acidic soil will have red petals was supported)

Future research – explain how the experiment could be improved in the future or expanded upon

Topics 8&9 cont’d

1cm = 10 mm 1mm = 1000 µm Microscope:

Coarse adjustment (only under low power) Fine adjustment (for both) Eyepiece (ocular) typically 10x Objectives (low typically 10x, high typically 40x) Total magnification = eyepiece x objective Images appear upside down and backwards and appear to

move in opposite direction High power has a SMALLER field of view and is

DARKER than low power!!

Topics 8&9 cont’d Chromatography- separates pigments into color

components (those that are more water soluble travel further up the paper)

Gel electrophoresis- restriction enzymes cut DNA from each individual into fragments of various sizes The DNA of each individual is loaded into a separate well

in the gel The gel is hooked up to a current (negative at the top and

positive at the bottom) as DNA has a negative charge it is drawn toward the bottom toward the positive charge

A banding pattern is created as the larger fragments settle toward the top and the smaller ones toward the bottom

Both techniques are used to determine evolutionary relationships (common ancestry)

Topics 8&9 cont’d

Indicators: Starch indicator (Lugol’s iodine)- goes from an amber/gold

color to a deep blue/purple in presence of starch

Glucose indicator (Benedict’s solution)- goes from a pale blue to an orange/green color in the presence of glucose WHEN HEATED!