AQA GCSE Biology B1

• What are cells?

  The building blocks of organisms
• Define eukaryotic cell

  Cells that have a true nucleus
• Define prokaryotic cell

  Cells that do not have a true nucleus
• What is in an animal cell?

  Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes
• What is in a plant cell?

  Same as animal plus: vacuole, chloroplasts, chlorophyll, cell wall
• What is in a yeast cell?

  Same as animal plus: temporary vacuole, cell wall
• What is in a bacterial cell?

  Cytoplasm, cell membrane, cell wall, ribosomes, chromosomes, plasmid, capsule, flagellum
• Function of nucleus

  The control centre of the cell, contains DNA
• Function of cytoplasm

  Where chemical reactions take place
• Function of cell membrane

  Controls the flow of substances into and out of the cell
• Function of mitochondria

  Releases energy into the cell in respiration
• Function of ribosomes

  Where protein synthesis takes place
• Function of vacuole

  Keeps the cell turgid (filled with plant sap)
• Function of chlorophyll

  Absorbed light energy in photosynthesis
• Function of cell wall

  Provides structure for the cell, made of cellulose
• Function of chromosomes

  Carries genetic information
• Function of plasmid

  Carries genetic information
• Function of capsule

  Protects against phagocytosis
• Function of flagellum

  Helps the cell move
• Adaptations of muscle cells

  Contain proteins that slide over each other making fibres contractContain mitochondria to transfer energyStore glycogen used in cellular respiration
• Adaptations of nerve cells

  Lots of dendrites to make connections to other nerve cellsThe axon carries the nerve impulses from one place to another and are often very longSynapses pass impulses to another cell or between a nerve and the muscle
• Adaptation of root hair cells

  Increase surface area for water to move up the cellHave mitochondria that transfer energy needed for transport of mineral ions into the cellHave a large permanent vacuole that speeds up the movement of water by osmosis
• Adaptations of sperm cells

  Long tail to whip to propel the sperm forwardMiddle section has lots of mitochondria which transfer energy to the tailLarge nucleus for the DNA that needs to be passed on
• Adaptations of red blood cells

  Are thin, so there is only a short distance for the oxygen to diffuse to reach the centre of the cell. The biconcave shape provides a large surface area compared to the volume of the red blood cell, allowing diffusion to happen efficiently
• Image size =

  magnification x real size
• Define DNA

  deoxyribonucleic acid, the genetic code which defines life
• Define gene

  A short section of DNA, carrying genetic information. The basic unit of inheritance
• Define allele

  Different forms of the same gene
• Define gametes

  male and female sex cells
• Define chromosomes

  Thread like structures made up of long coils of DNA and found in the nucleus of the cell
• Maternal DNA


  DNA that comes from your mother
• Paternal DNA


  DNA genes that comes from your father
• Define homolohous

  Same or similar chromosomes
• XX


  Female
• XY

  Male
• How many pairs of chromosomes do humans have?

  23 pairs
• Mitosis definition

  The division into two daughter cells that are genetically identical to each other and he original cell
• Why is ell division important?

  Repair, growth, reproduction
• The cell cycle:

  1. Chromosomes are replicated2. Chromosomes become shorter and fatter (condense)3. Chromosomes and their copy line up in the centre of spindle fibres4. The spindle fibres contract and pull the chromosomes apart5. Two new daughter cells are formed
• When do animal cells differentiate?

  in an early stage of development