Paper 2

• Alleles

  Genes that code for a specific characteristic
• Types of alleles

  • Dominant (big boy)
  • Recessive
• Dominant allele

  The one that will be expressed if there is a dominant and recessive allele for one characteristic
• Recessive allele

  The characteristic will be expressed if someone has two recessive alleles
• Heterozygous

  Having both dominant and recessive alleles
• Homozygous

  Having either all dominant or all recessive alleles
• Endocrine system

  Made up of glands that make hormones
• Pituitary gland

  Regulates growth, metabolism, and reproduction through the hormones it produces
• Nervous system

  Transmits signals between the brain and the rest of the body, including internal organs
• Neuron

  The basic unit of the nervous system
• Sensory neurons

  Send signals to the rest of the nervous system about the information they have received
• Motor neurons

  Cells in the brain and spinal cord that allow us to move, speak, swallow and breathe by sending commands from the brain to the muscles
• Relay neurons

  Found in the brain and spinal cord and allow sensory and motor neurons to communicate
• Synapse

  The gap between neurons
• Pollen

  The male sex cell in plant cells
• Ovum

  The female sex cell in plant cells
• Gamete

  A reproductive cell of an animal or plant
• Egg cell

  Female gamete in animals
• Sperm

  Male gamete in animals
• Sexual reproduction

  Reproduction between organisms, where the offspring is genetically different
• Asexual reproduction

  An organism is able to produce by itself, where the offspring are genetically identical
• Homeostasis

  How your body reacts to the environment around it and the environment inside of it to make sure it is functioning perfectly
• Levels maintained by homeostasis

  • Blood glucose concentration
  • Body temperature
  • Water levels
• Lungs

  Oxygenate our blood
• Brain

  Controls thought, memory, emotion, touch, motor skills, vision, breathing, temperature, hunger and every process that regulates our body
• Kidneys

  Remove waste from the blood and return the cleaned blood back to the body
• Genes

  The basic unit of heredity passed from parent to child
• Genome

  The complete set of DNA in an organism
• Type 1 diabetes

  When your body isn't able to produce insulin, you have to inject insulin in your blood stream
• Type 2 diabetes

  When your cells are unresponsive to insulin, you need to take medicine or keep their blood sugar levels low
• Genotype

  An organism's unique sequence of DNA
• Phenotype

  The physical characteristics of an organism
• Animals better adapted to their environment


  Are more likely to survive
• Animals less adapted to the environment


  Mostly end up dying
• Natural selection

  1. Animals that survive reproduce

  2. Pass on their well adapted genes (good genes)

  3. Animals less adapted to the environment don't survive
• There are 23 pairs of chromosomes making 46 chromosomes
• Interdependence

  Describes how organisms in a community depend on other organisms for vital services
• Abiotic factors

  • Temperature
  • Light intensity
  • Moisture levels
  • Soil pH
• Abiotic factors

  Non living factors of an ecosystem
• Biotic factors


  • Availability of food
  • New predators
  • New pathogens