Aqa a level Biology - Topic 2

• What are the 2 main types of organism?

  Eukaryotes and prokaryotes
• What cells are eukaryotic?

  Animal, plant, algal, fungal
• Name the 11 organelles in an animal cell

  1. Cell surface membrane2. Rough endoplasmic reticulum 3. Smooth endoplasmic reticulum4. Lysosome 5. Ribosome6. Golgi apparatus7. Mitochondria8. Nuclear envelope9, nucleolus10. Nucleus11. Cytoplasm
• Name the 14 organelles in a plant cell

  1. Cell surface membrane2. Rough endoplasmic reticulum 3. Smooth endoplasmic reticulum4. Lysosome 5. Ribosome6. Golgi apparatus7. Mitochondria8. Nuclear envelope9, nucleolus10. Nucleus11. Cytoplasm 12. Cell wall13. Vacuole14. Chloroplasts
• Name the difference between algal cells and plant cells


  Chloroplasts are different shape and size
• Name the two differences between plant cells and fungal cells

  1. Fungal cell walls are made of chitin not cellulose2. Fungal cells don't have chloroplasts
• What is a cell membrane and what is it's function?

  The membrane found on surface of animal cells and inside cell wall of other cells made of lipids and proteins.Regulates movement of substances into and out of cell & has receptor molecules which allow it to respond to chemicals like hormones
• Describe the nucleus and it's function

  Surrounded by a double membrane nuclear envelope and contains chromosomes and nucleolus.Controls the cells activity by by controlling the transcription of DNA. Nucleolus makes ribosomes
• Describe mitochondria and it's function

  Oval shape, double membrane- inner one is folded to form Cristae- inside is the matrix which contains enzymes involved in respiration The sit of aerobic respiration
• Describe chloroplasts and their function

  Small flattened structure surrounded by double membrane and has membranes inside called thylakoids. Thylakoids are stacked up to form grana which are linked together by lamellae. - the site where photosynthesis takes place
• Describe Golgi apparatus and it's function

  A group of fluid filled membrane bound flattened sacs. Vesicles often at edge of sacs - processes and packages new lipids and proteins, also makes lysosomes
• Describe Golgi vesicles and their function

  Small fluid filled sac in the cytoplasm, surrounded by membrane and produced by the Golgi apparatus - stores lipids and proteins made by the Golgi apparatus and transports them out of the cell
• Describe a lysosome?

  a membranous sac containing digestive enzymes that destroy debris and worn out organelles
• Describe a ribosome and it's function

  No membrane, Floats free or is attached to rough endoplasmic reticulum and is made up of proteins and RNA.- the site where proteins are made
• Describe rough endoplasmic reticulum and it's function

  A system of membranes enclosing a fluid filled space, surface covered with ribosomes.- folds and processes proteins that have been made at the ribosomes.
• Describe the smooth endoplasmic reticulum and it's function

  System of membranes enclosing fluid filled space.- synthesises and processes lipids
• Describe the cell wall and it's function

  Rigid structure surrounds cells in plants algae and fungi. Mainly made of cellulose and in fungi chitin- supports cells and prevents them from changing shape
• Describe the cell vacuole and it's function

  Membrane bound, found in cytoplasm, contains cell sap (sugar and salts) - keeps the cell rigid, involved in isolation of unwanted chemicals inside the cell
• Describe how epithelial cells are adapted for their function in the small intestine.

  - finger like projections called villi increase surface area for absorption and the epithelial cells on the villi have folds in their membrane called microvilli which increases surface area even more. - have lots of mitochondria to provide energy for the transport of digested food molecules into the cell
• Describe how red blood cells are adapted for their function

  Have no nucleus to make room for the oxygen carrying compound haemoglobin.
• Describe how sperm cells are adapted for their function

  Contain a lot of mitochondria to provide the large amount of energy they need to propel themselves towards an egg
• In multicellular eukaryotic organisms, specialised cells are grouped together to form...

  Tissue
• What is a tissue?

  A group of cells that act together to perform a specific function.
• What is an organ?

  groups of tissues working together
• What is an organ system?

  A group of organs working together
• What are prokaryotes?

  Single celled organisms
• Name 8 organelles in a prokaryotic cell

  1. Cytoplasm2. Ribosomes3. Cell surface membrane4. Cell wall5. Capsule ( some) 6. Plasmids7. Free floating dna 8. Flagellum (some)
• Explain the steps of binary fission in prokaryotic cell replication

  1, dna and plasmids replicate2. Cell gets bigger and dna loops move to opposite poles3. Cytoplasm begins to divide4. Cytoplasm divides and 2 daughter cells are produced
• Describe a virus.

  Acellular, non living, just nucleic acid surrounded by protein, invade cells and reproduce inside
• Describe the structure of a virus.

  Capsid(protein coat) with attachment proteins sticking out
• What are the 5 steps in viral replication?

  1. Virus attaches to host cell receptor proteins2. Genetic material is released into host cell3. Genetic material and proteins are replicated by host cell 'machinery'4. Viral components assemble 5. Replicated viruses released from host cell
• What is magnification?


  How much bigger the image is that the specimen
• How would you calculate the magnification of an image that is 5mm side and the specimen is 0.05mm wide?

  5mm/0.05 = x100
• How do you calculate the size of an image?

  Magnification x size of object
• How do you calculate the size of the real object?

  Size of image/ magnification
• What is resolution?

  How detailed the image is - how well a microscope distinguishes between 2 points that are close together
• How do optical microscopes form an image?

  They use light to form an image
• What is the maximum resolution of an optical microscope?

  0.2 micrometers
• What organelles could you view under an optical microscopes?

  Ribosomes, endoplasmic reticulum, lysosomes, nucleus (under 0.2 micrometers)
• What is the maximum useful magnification of an optical microscope?

  About x1500