biology paper 2

• Homeostasis is an organism's ability to regulate internal conditions even when external conditions change, crucial for optimal enzyme function
• The nervous system consists of the CNS (central nervous system - brain and spinal cord) and the PNS (peripheral nervous system - nerves throughout the body)
• A reflex arc is when a signal bypasses the brain and goes straight through the spine to the affector, resulting in a faster response
• Glands, like salivary glands, can be affectors producing specific chemicals needed by the body depending on the situation
• Thermoregulation is the body controlling its internal temperature by the brain sensing blood temperature and sending signals to effectors to lose heat to the surroundings
• The endocrine system is a system of glands that produce hormones affecting various bodily functions, slower than the nervous system
• The pituitary gland in the brain is considered the main gland, producing hormones that travel to other glands in the body to regulate chemical production
• The pancreas regulates blood glucose levels: insulin moves glucose from blood into cells, while glucagon converts glycogen back into glucose when levels are low
• Menstruation in females involves the maturation of eggs, production of estrogen, and thickening of the uterus lining, controlled by hormones like FSH and LH
• Myopia is shortsightedness, while hyperopia is long-sightedness; glasses or contact lenses are used to correct these vision issues
• Antidiuretic hormone (ADH) is produced in the pituitary gland, causing the kidneys to reabsorb more water into the bloodstream, maintaining water balance
• In the ovary, maturation causes the production of estrogen, thickening the uterus lining, inhibiting FSH production, and triggering the release of LH (luteinizing hormone) for egg release
• Progesterone, produced by the ovaries, maintains the uterus lining, crucial for pregnancy; contraception methods include inhibiting FSH production, progesterone injections to prevent egg release, implants, condoms, diaphragms, and IUDs
• Infertility issues can result from insufficient FSH or LH production, treated with injections; IVF (in vitro fertilization) is a costly solution for more complex problems
• Adrenaline increases heart and breathing rate in stressful situations for fight or flight response; thyroxin, secreted by the thyroid, controls metabolic rate
• Plants have hormones like gibberellins for seed germination and flowering, ethene for fruit ripening, and auxins for Chute and root growth, showing phototropism and geotropism
• Genome refers to all genetic material in an organism, stored in DNA; genes are sections of DNA that code for specific proteins, influencing phenotype
• DNA is made of nucleotides (A, T, C, G) forming a double helix; genes code for proteins through mRNA copying, translated into amino acids, affecting protein function
• Mutations can alter gene function; epigenetics studies how DNA influences gene expression without changing the DNA sequence
• Inheritance involves genes passed from parents, leading to variation; dominant and recessive alleles determine traits like eye color, with Punnett squares predicting offspring outcomes
• Variation results from inherited genes and environmental factors; Darwin's theory of evolution states random variations can lead to better adaptation to the environment, influencing survival and reproduction
• Resistance to antibiotics is a concern due to the potential production of more resistant bacteria, emphasizing the importance of using antibiotics only when absolutely necessary
• Completing the whole course of antibiotics is crucial to ensure weaker bacteria are killed off completely, preventing the survival and reproduction of more resistant ones
• Organisms producing fertile offspring are considered to be of the same species; for example, tigers and lions, although capable of producing offspring, are not considered the same species as their offspring are infertile
• Selective breeding can enhance desired characteristics in living things, such as breeding dogs to produce specific breeds like Labradors or Pugs
• Advancements in biology, including genetic modification, allow for the enhancement of characteristics in organisms; for instance, genetically modifying crops to boost yields or nutritional value, like golden rice with inserted genes producing vitamin A
• Genetic engineering involves chemically cutting a gene from an organism with desired characteristics, inserting it into a vector like a bacteria plasmid or virus, and then inserting it into another organism, ensuring the gene is present in every cell of the organism as it grows
• Cloning involves making exact copies of plants or animals; while cloning plants is relatively easier through cuttings or tissue culture, cloning animals involves more complex processes like splitting embryo cells or transferring nuclei into egg cells
• Fossils are the remains of organisms that died long ago, often preserved as bones replaced by minerals or as footprints in hardened mud, providing valuable insights into past life forms
• Classification of organisms includes Kingdom, Phylum, Class, Order, Family, Genus, and Species, with the binomial Latin name combining the genus and species; the addition of the domain level above Kingdom was later introduced, with three domains: Archaea, Bacteria, and Eukarya
• Ecology studies how organisms interact in ecosystems, where they compete for resources like food, water, space, and mates, showcasing interdependence and the roles of abiotic and biotic factors in ecosystem dynamics
• The food chain illustrates the flow of biomass and energy in an ecosystem, from producers (plants or algae) to primary consumers (herbivores), secondary consumers (carnivores or omnivores), and tertiary consumers, with apex predators at the top of the chain
• Population numbers in ecosystems fluctuate over time, influenced by factors like competition, predation, and environmental changes, highlighting the dynamic nature of ecosystems
• Biodiversity refers to the variety of organisms in an ecosystem, with high biodiversity contributing to ecosystem stability; human activities like deforestation and pollution often lead to reduced biodiversity and environmental challenges
• The Pyramid of Biomass in a food chain demonstrates the transfer of mass and energy between trophic levels, showing how biomass decreases as it moves up the chain due to inefficiencies and losses in energy transfer
• Food security is a critical issue influenced by factors like increasing world population, changing diets, transportation of food, and conflicts, prompting the need for sustainable farming practices and fishing to ensure long-term food availability