biology

• Sub-cellular structures in an animal cell

  Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes
• Cytoplasm function

  Where most chemical reactions take place
• Mitochondria function

  Site of aerobic respiration
• Ribosomes function

  site of protein synthesis
• What is the cell wall made of?

  cellulose
• Chloroplast function

  Site of photosynthesis, contain chlorophyll which absorbs light for photosynthesis.
• where is DNA found in prokaryotic cells?

  Free in the cytoplasm
• Equation for magnification

  magnification = image size/actual size
• Millimeters to micrometers

  1 mm = 1000 micrometers
• millimeters to nanometers

  1 mm = 1000000 nm
• micrometres to nanometres

  1 um= 1000nm
• Differentiation

  process in which cells become specialized in structure and function
• Stem cells in plants

  meristem cells; often at tips of roots, stems, and branches
• How is a sperm cell specialised?

  Long tail

  streamlined head to help reach the egg

  lots of mitochondria for energy needed

  carries enzymes in its head (acrosome) to digest the egg cell membrane
• How is a nerve cell specialised?

  They are long

  branches connections at their ends to connect to other cells

  fatty (myelin) sheath surrounds them, increases the speed the messages travel.
• How is a muscle cell specialised?

  Cells are long, to contract and relax

  many mitochondria for energy
• How is a root hair cell specialised?

  It has lots of mitochondria for active transport of minerals

  a long projection to increase the surface area for absorption water and minerals
• What happens in stage 1 of the cell cycle?

  The cells increase mass, replicate their DNA to form two copies of each chromosome and increase the number of mitochondria, ribosomes and chloroplasts
• What happens in stage 2 of the cell cycle?

  one set of chromosomes is pulled to each end of the dividing cell and the nucleus divides
• What happens in stage 3 of the cell cycle?

  the cytoplasm and cell membrane divide to form two new identical cells
• conditions for bacteria growth, how often can they divide?

  lots of nutrients, warm environment, as often as every 20 minutes.
• what is the distance around a paper disc of antibiotic called?

  inhibition zone
• Diffusion

  Movement of molecules from an area of higher concentration to an area of lower concentration.
• Osmosis

  Diffusion of water through a selectively permeable membrane, from an area of high water concentration to low water concentration.
• Adaptations of alveoli

  Thin walls

  Moist

  Large surface area

  Lots of capillaries for a good blood supply
• small intestine adaptations

  - thin wall covered in villi

  - villi gives a large surface area

  - they contain blood capillaries to carry absorbed food molecules
• Gills adaptations

  - large surface area from gill filaments

  - good blood supply

  - thin layers

  - lamellae increase surface area
• Types of pathogens

  viruses, bacteria, protists, fungi
• How can bacteria cause disease?

  By producing toxins that damage cells and tissues
• how do viruses make you feel ill

  They replicate themselves by invading your cells and using the cells' machinery to produce many copies of themselves. The cell will then usually burst, releasing all the new viruses. This cell damage is what makes you feel ill.
• how are protists spread

  by vectors
• Measles pathogen

  virus
• Measles symptoms

  Fever and a red skin rash
• Measles prevention and treatment

  -MMR vaccine

  -No antiviral treatment available
• HIV pathogen

  virus
• How can the spread of HIV be prevented?

  Use condoms

  Not sharing needles

  Screening bloods used in transfusions

  Regular use of antiretroviral drugs
• What does HIV do?

  attacks the immune system
• TMV pathogen

  virus
• TMV symptoms

  Mosaic pattern of discolouration on leaves
• Rose black spot pathogen

  Fungi