Biology paper 2

• Retina

  Contains rods (detect light intensity) and cones (detect color)
• Myopia

  Shortsightedness - can't focus on far objects
• Hyperopia

  Longsightedness - can't focus on near objects
• Thermoregulation

  Brain senses blood temperature

  Sends nervous and hormonal signals to effectors

  Effectors cause body to lose or retain heat
• Endocrine system

  System of glands that produce hormones that travel to effectors via the blood
• Pituitary gland

  Main or master gland that produces hormones in response to stimuli
• Pancreas

  Produces insulin to regulate blood glucose levels
• Type 1 diabetes

  Pancreas can't produce enough insulin
• Type 2 diabetes

  Cells no longer absorb glucose properly
• Water and nitrogen balance

  Body loses water through exhaling, sweating, urinating

  Kidneys remove excess water from blood and mix with urea to form urine

  Antidiuretic hormone (ADH) regulates water reabsorption in kidneys
• Dialysis

  Process that does the job of non-functioning kidneys
• Menstrual cycle

  FSH causes egg maturation and estrogen production

  LH causes egg release

  Progesterone maintains uterus lining
• IVF

  In vitro fertilization - eggs harvested and fertilized in lab, then implanted
• Adrenaline

  Hormone that increases heart and breathing rate in stressful situations
• Thyroxin

  Hormone secreted by thyroid that controls metabolic rate
• Plant hormones

  Gibberellins - seed germination, flowering, fruit size

  Ethylene - fruit ripening

  Auxins - shoot and root growth
• Meiosis

  Chromosomes copied, paired, genes swapped, cell divides twice to make haploid gametes
• Asexual reproduction

  Daughter cells genetically identical to parent
• Genome

  All the genetic material in an organism
• Gene

  Section of DNA that codes for a specific protein
• Human Genome Project

  Mapped out what every gene is responsible for
• Genotype

  Genetic code stored in DNA
• Phenotype

  How the genetic code is expressed in characteristics
• Nucleotides

  Monomers that make up DNA
• Asexual reproduction

  Only one parent is needed, e.g. a plant on its own can still reproduce to ensure species survival
• Parasite that causes malaria

  Can reproduce both sexually and asexually
• Genome

  The term given to all the genetic material in an organism
• DNA

  A two-stranded polymer in a double helix shape that stores the genetic code
• Gene

  A section of DNA that codes for a specific protein
• The Human Genome Project completed its initial goal in 2003 when scientists mapped out what every gene is responsible for coding
• Genotype

  The code stored in your DNA specifically
• Phenotype

  How the genotype is expressed in your characteristics and physiology
• Nucleotides

  The monomers between the two DNA strands, made from a sugar and phosphate group (A, T, C, G)
• A and T always match to each other in the DNA sequence, as do C and G
• Triplet code

  Every three DNA bases code for an amino acid
• Protein synthesis

  1. DNA sequence copied by mRNA

  2. mRNA taken to ribosome

  3. Amino acids connected in order to make protein

  4. Protein folding affects function
• Harmful mutation

  Changes a gene so much that it results in a protein being synthesized that doesn't do its job
• Epigenetics

  DNA that doesn't directly code for proteins but influences how other genes are expressed
• Alleles

  Different types of the same gene
• Dominant allele

  Results in a characteristic being expressed even if another recessive allele is present