ALL OF BIO PAPER 2

• Homeostasis is an organism's ability to regulate internal conditions even when external conditions change, crucial for optimal enzyme activity
• 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 is when a signal bypasses the brain and goes straight through the spine to the affector, known as a reflex arc
• Glands can be effectors, producing specific chemicals your body needs depending on the situation, like salivary glands producing saliva when you eat
• Investigating reaction times involves dropping a ruler without warning and measuring the distance it falls before being caught, introducing variables like stimulants or depressants
• The endocrine system produces hormones that travel via the blood to affectors, slower than signals carried by the nervous system
• The pituitary gland is considered the main gland, producing hormones that travel to other glands in the body to start producing specific chemicals
• The pancreas regulates blood glucose levels: insulin moves glucose from blood into cells, while glucagon converts glycogen back into glucose when levels are low
• Reproduction involves menstruation in females, where eggs mature due to FSH, estrogen thickens the uterus lining, and LH causes egg release
• In the ovary, maturation causes the production of estrogen, thickening the uterus lining, inhibiting FSH production, and triggering the release of LH which leads to egg release
• Progesterone, produced by the ovaries, maintains the uterus lining, crucial for pregnancy
• Contraception methods include pills inhibiting FSH production, progesterone injections preventing egg release, implants slowly releasing hormones, condoms, diaphragms as barriers, and IUDs preventing fertilized egg implantation
• Adrenaline increases heart and breathing rate in stressful situations for fight or flight response, while thyroxin controls metabolic rate
• Inheritance involves genes passed from parents, with variation due to meiosis and mitosis; sexual reproduction leads to genetic diversity, asexual reproduction results in clones
• Punnet squares predict offspring phenotypes based on parents' genotypes; alleles can be dominant or recessive, influencing traits like eye color
• Cystic fibrosis is an example of a recessive genetic disorder; human DNA in 23 pairs of chromosomes, with sex determined by the XX (female) or XY (male) pair
• Variation results from inherited genes and environmental factors; Darwin's theory of evolution states random variations lead to better-adapted organisms surviving and reproducing
• Antibiotic resistance is a concern due to the production of resistant bacteria, emphasizing the importance of using antibiotics only when necessary and completing the full course to prevent the survival of more resistant bacteria
• Organisms producing fertile offspring are considered to be of the same species; for example, tigers and lions can produce offspring, but as they are infertile, they are not considered the same species
• Selective breeding can enhance desired characteristics in living things, such as breeding dogs to produce specific breeds like Labradors or Pugs
• Advancements in biology allow for genetic modification of organisms, enabling the production of substances like insulin from genetically modified bacteria to treat conditions like diabetes
• Genetic engineering involves cutting a gene from an organism with desired characteristics, inserting it into a vector like a bacteria plasmid or virus, and then into another organism, ensuring the gene is present in every cell as it grows
• Classification of organisms includes Kingdom, Phylum, Class, Order, Family, Genus, and Species; the binomial Latin name combines the genus and species