Living Environment Regents Exam - Key Concepts

Molecules and Cells

• Amino acids are the building blocks of polypeptides (proteins).
• Monosaccharides are the building blocks of polysaccharides (starch).
• Enzymes are proteins that catalyze chemical reactions; their 3D shape is crucial for function.
• Bacteria are prokaryotic cells (no nucleus or membrane-bound organelles).
• Eukaryotic cells contain a nucleus with DNA.
• Chloroplasts (in autotrophs) produce glucose via photosynthesis.
• Mitochondria produce ATP energy through aerobic cellular respiration.
• The cell membrane is selectively permeable.
• Diffusion moves small, uncharged molecules from high to low concentration.
• A large surface area increases the rate of diffusion.
• Active transport uses ATP to move materials across the cell membrane.
• Receptor proteins bind to specific molecules.
• Cells differentiate to perform specific functions.
• Mitosis: diploid cell divides into two identical diploid daughter cells.
• Cancer: uncontrolled cell division by mitosis.
• Meiosis produces haploid cells and increases genetic variation.
• Asexual reproduction yields offspring genetically identical to the parent.
• Cloning of mammals is possible with modern cell biology techniques.

Heredity

• Mutations/chromosomal abnormalities in gamete-producing cells can be inherited.
• Testosterone stimulates sperm production and secondary sex characteristics in males.
• Fertilization: fusion of haploid sperm and egg to form a diploid zygote.
• Cleavage: mitotic cell division in embryonic development without cell size change.
• Amnion and placenta maintain homeostasis during intrauterine development.
• Mating parents with desirable traits increases the chance of offspring inheriting those traits.
• Genetic diseases are inherited via DNA during sexual reproduction.
• Chromosomes contain hundreds of genes.
• Environmental factors can turn genes on or off.
• DNA replication creates identical copies of DNA, following complementary base pairing (A-T, C-G).
• DNA unzips during replication as weak H bonds break.
• $DNA \rightarrow RNA \rightarrow Protein$
• DNA mutations can cause abnormal protein production or halt it altogether.
• Transformation: inserting recombinant plasmids into bacteria to produce new proteins.
• Transduction: adding recombinant viral DNA to human cells.
• Electrophoresis separates DNA fragments by size.

Evolution

• Organisms have structural adaptations for survival.
• Natural selection can lead to the evolution of new species.
• The fossil record supports evolution.
• The first organisms were single-celled prokaryotes.
• Evolution rate varies among organisms.
• Allele frequency: percentage of alleles for a trait in a population.
• Small, isolated populations may evolve into new, specialized species or become extinct.
• Genetic changes drive variation and new species formation.
• Genetic diversity enhances a population's ability to adapt to environmental changes.

Homeostasis

• Organisms' organs and systems maintain homeostasis.
• Digestive enzymes hydrolyze carbohydrates, proteins, and lipids.
• The circulatory system transports plasma and cells while the lymphatic system transports water to cells.
• The right side of the heart pumps deoxygenated blood to lungs, the left pumps oxygenated blood to cells.
• White blood cells fight pathogens.
• Antibodies (produced by white blood cells) bind to pathogens.
• Organ transplants can trigger immune rejection.
• Vaccines contain weakened pathogens or their proteins.
• The nervous and endocrine systems coordinate actions.
• Hormones are chemical messengers that bind to target cell receptors.
• Insulin (from the pancreas) lowers blood glucose.
• Hormonal feedback mechanisms maintain homeostasis.
• Kidneys regulate urine composition and water balance.
• Stomates regulate gas exchange and water loss in leaves.
• Chlorophyll captures light energy for photosynthesis.
• Photosynthesis consumes carbon dioxide and produces oxygen.
• Glucose is the initial stable product of photosynthesis.
• Cellular respiration produces ATP energy from glucose and oxygen in mitochondria.
• Carbon dioxide is a waste product of cellular respiration.
• All organisms respire to produce ATP.
• Photosynthesis and respiration stabilize atmospheric oxygen and carbon dioxide levels.

Ecology

• Energy is transferred through food webs.
• Decomposers recycle materials from dead organisms.
• Food chains start with producers, continue with consumers, and end with decomposers.
• Only 10% of energy transfers to the next trophic level due to metabolic use.
• Plants hold the most energy in an ecosystem.
• Changes in one population affect others in the food web.
• Host-parasite relationships benefit one organism (parasite) at the expense of the other (host).
• Stable ecosystems have complex food webs and high biodiversity.
• Biomes are regions with similar climate, plants, and animals.
• Ecological succession leads to climax communities over time.
  • Water ecosystems: pond and lakes into marshes, into swamps, into dry land.
  • Land ecosystems: rock into soil by lichens acid secretions, into mosses, into grasses, into shrubs, into conifers and then into deciduous forests (leafy trees), called a climax community: the most mature kind of community.
• Climax communities are stable unless disrupted.

Human Impact and Scientific Method

• Human population growth has increased exponentially (past 60 years).
• Increased human population leads to resource depletion and environmental damage.
• Pollution disrupts ecosystems and endangers species.
• Acid rain is caused by factory emissions (nitrogen and sulfur).
• Pesticides and wastes harm wildlife and reduce biodiversity.
• Ozone layer destruction increases ultraviolet radiation.
• Greenhouse gases (CO2, CH4) contribute to global warming.
• Imported species can disrupt food webs and cause environmental damage.
• Overpopulation increases competition for resources.
• Carrying capacity: maximum population size an area can support.
• Biological controls are preferable to chemical controls for population regulation.
• Chemical pesticides cause lasting environmental damage.
• The problem is framed as a question.
• The hypothesis is a testable statement.
• A conclusion is based on experimental data.
• An inference is supported by the data and conclusion.
• Experiments must be repeatable to be valid.
• The independent variable is known before the experiment.
• The dependent variable is measured during the experiment.
• Experiments must have a control group.
• Conditions must be identical except for the variable being tested.
• Multiple setups and averaging results are essential for valid data.
• Adjust microscope brightness with the diaphragm and use the fine adjustment knob at high power.
• Wet mount slides: to view live specimens under a microscope
• Indicators:
  • Bromothymol Blue: carbon dioxide.
  • Iodine (Lugol's solution): starch.
  • Wide range pH paper: acidity/basicity.
• Data tables: for organizing data.
• Line graphs: for two sets of numerical data with labeled axis.
• Evolution:
  • Gradualism: slow, steady pace (Darwin).
  • Punctuated Equilibrium: rapid bursts with stability (Gould).