Population Dynamics and Growth

Population Dynamics

• Global human population remained very low until 2000-4000 years ago.
• Agriculture caused a gradual increase (alongside technological and cultural progress).
• The last 150-200 years saw exponential population increase due to the Industrial Revolution and advances in medicine and agriculture.
• Greater equality for women leads to smaller families.
• Improved living & health standards, along with retirement benefits, reduce the need for large families.
• Urbanization means fewer children are needed.
• Ecological density is calculated by dividing the number of organisms by the space available to them.
• A habitat with 350 deer in a valley with 530 km² area, and 80 km² of uninhabitable area results to an ecological density of 0.78 deer/km².
• Logistic growth can also be described as S-shaped or sigmoid growth.
• An increasing deer population indicates it hasn't reached its habitat's carrying capacity, meaning births exceed deaths.
• A competitor consuming the same resources as deer would decrease deer numbers, effectively lowering the environment's carrying capacity.

Biochemistry

• Condensation, Redox, Neutralization, and Hydrolysis are all forms of reactions.
• A covalent bond forms when atoms share valence electrons, which enables each atom to obtain a full valence shell.
• Exocytosis removes materials such as wastes from the cell and Endocytosis brings materials such as water and solid particles into the cell; both are active transport processes that need a cellular membrane.
• Salt creates a hypertonic environment relative to the inside of cells, thus, water migrates out by osmosis.

Correct Triglyceride Molecule Structure

• Reactants are Glycerol and 3 Fatty acids.
• Product is Triglyceride.
• Functional groups are Hydroxyl (OH) and Carboxyl (H-C=O).
• Main linkage is Ester linkage.
• Enzymes attach to reactants and position them to lower the activation energy.

Metabolic Processes

• ATP features three phosphate tails for energy storage, where each phosphate group has a negative charge that repels each other.
• Potential energy is liberated upon breaking the last bond between phosphate groups, enabling cell function (ATP → ADP).
• Adding energy and a phosphate group source reforms ATP.
• ATP converts to ADP to make energy for the cell.
• The matter and energy obtained from consumed foods enables the body to produce ATP again.
• Photosynthesis: 6 CO₂ + 6 H2O + energy → C6H12O6 + 6 O₂
• Cellular Respiration: C6H12O6 + 6 O₂ → 6 CO₂ + 6 H2O + ATP energy
• Fermentation produces a strong odour of alcohol.

Photosynthesis

• Light-dependent reactions occur in the thylakoid membrane to convert light energy to chemical energy stored in ATP and NADPH, producing oxygen.
• Light-independent reactions occur in the stroma to use ATP and NADPH to make glucose, producing glucose.
• The dark reaction receives energy captured from sunlight stored in ATP and NADPH molecules.
• Photosystem 680, NADPH, Calvin Cycle, Krebs Cycle, Glycolysis, Pyruvate Oxidation, and Glucose are all parts of cellular reactions.

Molecular Genetics

• Watson and Crick explained Deoxyribose Nucleic Acid (DNA) as a double helix (or twisted ladder) that is made of nucleotides.
• Each nucleotide contains a nitrogen base, a sugar, and a phosphate.
• The sugars and phosphates of the nucleotides make up the sides of the ladder, the nitrogen bases make up the rungs.
• DNA gyrase prevents helix from super-coiling.
• DNA helicase unwinds and unzips DNA helix by breaking the hydrogen bonds between nitrogen bases.
• DNA polymerase III catalyzes the formation of phosphodiester bonds between adjacent deoxyribonucleoside triphosphates and is responsible for “stringing” nucleotides together.
• DNA ligase glues together Okazaki fragments.
• RNA primase lays down RNA primers.
• DNA, mRNA, and Amino Acids are types of codons.
• TAC (DNA) = AUG (mRNA) = Methionine,
• CAG (DNA) = GUC (mRNA) = Valine,
• GTA (DNA) = CAU (mRNA) = Histidine,
• GAC (DNA) = CUG (mRNA) = Leucine

Missense mutation

• Missense mutation results in a different codon, which changes the sequence of amino acids and can change the resulting protein.

Homeostasis

• Filtration is the movement of fluids from the blood into Bowman's capsule, which is called filtratrion.
• Plasma protein, blood cells, and platelets are too large to move through the pores of the glomerulus, while smaller molecules pass through the walls and enter the nephron using passive transport.
• Reabsorption is the transfer of essential solutes and water from the nephron back into the blood.
• Active transport moves sodium ions, glucose, and amino acids back into the blood.
• Passive transport moves water from the nephron back into the blood.
• Secretion is the movement of materials, such as nitrogen-containing waste, excess hydrogen ions, and some minerals and drugs, secreted into the urine, using passive transport.

Homeostasis and Hormones

• Estrogen is produced in the ovaries, which targets developing follicles and thickens the uterus lining, causes the egg to mature (undergo meiosis), as well as develops the female's secondary sex characteristics.
• Cortisol is produced in the adrenal cortex to target muscles and the liver, to increase the amount of amino acids in the blood (that the liver converts to glucose for energy) and to convert fats to fatty acids to produce energy for the body
• Depolarization creates a positive charge inside the nerve membrane, causing sodium gates to close and stopping sodium influx.
• A sodium/potassium pump then restores the resting membrane condition by moving three sodium ions out and two potassium ions in.
• Energy for the pump comes from ATP.
• Restoring the nerve membrane's original polarity is called repolarization.

This covers human population growth from early times to the present, noting the impact of agriculture, the Industrial Revolution, and societal changes such as greater equality for women. Additionally, it explains ecological density calculations and logistic growth patterns in populations. Increased living standards impact family size.