biology paper 2

• Homeostasis


  An organism's ability to regulate internal conditions even when external conditions change
• Nervous system

  • Central nervous system (brain and spinal cord)
  • Peripheral nervous system (nerves throughout the body)
• Reflex arc


  1. Receptor detects stimulus

  2. Electrical signal travels to spine

  3. Signal bypasses brain and goes straight to effector
• Reaction time


  Time taken for a person to respond to a stimulus
• Accommodation


  Eye's ability to change lens shape to focus light from objects at different distances
• Myopia


  Shortsightedness
• Hyperopia


  Longsightedness
• Thermoregulation


  Body's control of internal temperature
• Endocrine system


  • System of glands that produce hormones
• Insulin


  Hormone produced by pancreas that causes glucose to move from blood into cells
• Glucagon


  Hormone produced by pancreas that causes liver and muscles to convert glycogen into glucose
• Type 1 diabetes


  Pancreas cannot produce enough insulin
• Type 2 diabetes


  Cells no longer absorb glucose properly
• Kidney function


  1. Filters blood

  2. Reabsorbs useful substances

  3. Produces urine
• Antidiuretic hormone (ADH)


  Hormone produced in pituitary gland that causes kidneys to reabsorb more water
• Menstruation


  Cyclical shedding of uterus lining in females after puberty
• In vitro fertilization (IVF)


  Fertilization of egg by sperm outside the body, then implantation in uterus
• Adrenaline


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


  Hormone secreted by thyroid that controls metabolic rate
• Meiosis


  Cell division that produces gametes with half the normal number of chromosomes
• Mitosis


  Cell division that produces genetically identical daughter cells
• Genome


  All the genetic material in an organism
• Gene


  Section of DNA that codes for a specific protein
• Genotype


  Genetic code stored in DNA
• Phenotype


  How the genetic code is expressed in an organism's characteristics
• Asexual reproduction


  Only one parent is needed, e.g. a plant on its own can still reproduce to survive
• Some parasites and fungi 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
• Monomers in DNA


  • Nucleotides (made from a sugar, phosphate group, and one of 4 types: A, T, C, G)
• A and T, and C and G always match in the DNA sequence
• Protein synthesis


  1. DNA sequence copied to mRNA

  2. mRNA taken to ribosome

  3. Amino acids connected in order to form protein
• Harmful mutation


  Changes a gene so much that it results in a protein being synthesized that doesn't do its job
• Some DNA doesn't directly code for proteins but influences how other genes are expressed (epigenetics)
• Allele


  Different versions of the same gene
• Dominant allele


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