biology

• gradient

  gradient = change in y / change in x
• magnification 


  magnification = image size / real size
• WHO world health organisation is responsible for ways for coordinating ways to improve health
• Physical well-being includes being free from disease, eating and sleeping well, getting regular activity, and limiting the intake of harmful substances such as alcohol and drugs.
• Social well-being includes how well you get on with other people,

  and also how your surroundings affect vou
• Mental well-being includes how you feel about yourself.
• diploid

  
  

  haploid

  Diploid =46

  
  

  Haploid = 23
• Where is dna found?

  Nucleus > Chromosomes > DNA > Genes
• What happens during Mitosis?

  By mitosis a cell splits to create two identical copies of the original cell.
• What happens during Meiosis?

  In meiosis cells split to form new cells with half the usual number of chromosomes, to produce gametes for sexual reproduction.
• Structure of DNA - main

  Double helix shape

  
  

  two strands that are linked together by base pairs
• Structure of DNA - Base Pairs

  Adenine - Thymine

  Guanine - Cytosine

  
  

  Hydrogen bonding

  
  

  They are known as complementary base pairs
• Structure of DNA - Backbone

  Held together with pentosugars and phosphate
• Homozygous

  
  

  Hetrozygous


  Homozygous = Both alleles for one gene are the same (e.g. BB or bb)

  
  

  Hetrozygous =The alleles for one gene are different (e.g. Bb)
• What is an allele?

  Different versions of the same type of gene
• Genotype

  
  

  Phenotype

  Genotype = The alleles that an organism has

  - e.g. Pp

  
  

  Phenotype = What the organism looks like

  - e.g. Do they have it?
• Dominant

  
  

  Recessive


  Dominant = If the allele is present it will always be expressed in the phenotype(Upper Case)

  
  

  Recessive = Both alleles needed to be expressed in the phenotype (Lower case)
• Boys and girls sex chromosomes

  Boys = XY

  
  

  Girls = XX
• What is a gene mutation?

  Change in the sequence of bases in the genetic code

  
  

  Cause variation
• Human Genome Project

  Map a persons genome to indicate the risk of developing diseases that are caused by different alleles of genes.

  
  

  predicts the cure.
• When do mutations occur?

  When there is a mistake in copying dna during cell division
• Many mutations have no effect on the phenotype. Explain why.


  It cannot effect the phenotype because they produce amino acids which produce similar proteins.
• What is the name given to the process that causes cells to become specialized?

  Differentiaton
• Why do red blood cells have a large surface area?

  So oxygen can pass through.
• Stages of mitosis

  -Mother cell

  -DNA Replication

  -Cell division

  -Two daughter cells
• Stages of Meiosis

  -Inter phase

  -Meiosis 1

  -2 Daughter Cells

  -Meiosis 2

  -4 Daughter Cells
• What is differentiation?

  Where an unspecialised cell turns into a very specific cell with a specific function
• What is a stimulus?

  Changes to the environment which the body responds to.
• plant growth stages

  Mitosis - Cell division

  
  

  Elongation - Cell wall loosens links between cellulose molecules allowing water to enter and causing expansion of the vacuole and cytoplasm

  
  

  Differentiation - The cells differentiate into all the different specialist cells that the plant needs.
• Animal cells

  Mitochondria - respiration

  Cell membrane - Controls what goes in and out of the cell.

  Nucleus - Controls the cell

  Ribosomes - Protein synthesis

  Cytoplasm - chemical reaction
• Plant cell

  Mitochondria - respiration

  Cell membrane - Controls what goes in and out of the cell.

  Nucleus - Controls the cell

  Ribosomes - Protein synthesis

  Cytoplasm - chemical reaction

  Vacuole - filled with cell sap , keep it turgid

  Cell wall - Protects the cell

  Chloroplasts - contain chlorophyll, absorbs light energy for photosynthesis
• Nervous system route

  Stimulus > receptor cells > sensory neuron > CNS > Motor neuron > Effector > Response
• What does the CNS control

  The body :

  Brain

  Spinal cord
• What is a synapse?

  Gaps between neurons

  
  

  Impulses travel across as neurotransmitters from one axon terminal to the dendrite of the next neuron. The neurotransmitters attach to the receptors and the impulse is generated again.
• Why is Mitosis important in unicellular and multicellular organisms?

  In unicellular organisms mitosis is a type of asexual reproduction, making identical copies of a single cell.

  In multicellular organisms, mitosis produces more cells for growth and repair.
• How to work out length of object

  Actual size = Image size ÷ magnification
• What does resolution mean?


  Resolution is the ability to distinguish between two points as separate structures. The level of detail that can be seen using a microscope.
• prokaryotic

  
  

  Eukaryotic


  prokaryotic = No nucleus

  
  

  Eukaryotic = Nucleus
• Sperm cell =

  sperm cell has

  a long tail

  enzymes in the head to get to the egg
• egg cell =


  contains yolk which acts as a food source