8 Life Processes
Movement - change in position
Respiration - release in energy
Sensitivity -response to stimuli
Growth - increase in mass (cell number)
Reproduction - produce offspring
Excretion - removal of metabolic waste
Nutrition - take in or produce food
* Homeostasis - controlling internal conditions
Cell Structures 1
Enzymes are biological catalysts that control the reactions in a cell.
Optimum temperature - the temperature it works better at. If it goes above optimum temperature then it denatures. This cause the active site to change shape and the subtrate no longer fits, the bonds that hold the enzyme together break.
Cells break down small food molecules that have been assimilated from the gut to release the stored chemical energy in the process of cellular respiration.The chemical energy is used for muscle contraction, active transport, building up large molecules and cell division.
In aerobic respiration oxygen is used to oxidise food. The waste products are CO2 and H2O.
Glucose + oxygen ----> carbon dioxide + water (+ energy)
C6H12O6 + 6O2 ----> 6CO2 + 6H2O
In anearobic respiration cells respire without oxygen. Glucose is not completely broken down and less energy is released.
In yeast the waste products of this are ethanol and carbon dioxide:
Glucose ----> ethanol + carbon dioxide (+ some energy)
In animal cells the waste product is lactic acid:
Glucose ----> lactic acid (+ some energy)
Movement into and out of cells
Diffusion - the movement of of molecules from a high concentration to a low concentration.
E.g. alveoli and small intestine.
Osmosis - movement of water from a high concentration to a low concentration through a semi permeable membrane.
Active transport - movement of substances from a low concentration to a high concentration, requires energy.
E.g. root hair cells.
Levels of Organisation
Organelles: structures inside a cell (e.g. nucleus).
Tissues: a group of cells working together to carry out a specific.
Organ: a group of tissues working together to carry out a specific function.
System: a group of organs working together to carry out a specific function. (e.g. digestive, reproductive, circulatory, respiratory, urinary, nervous, endocrine)
Nerve Cell (neurone) - elongated part of a cell (axon) for carrying nerve impulses.
Smooth muscle cell from thewall of the intestine - elongated, can contract to move through the gut.
Xylem vessel from plant stem - dead, hollow cell with strengthening rings. Carries water of stem.
Guard cells from surface of a leaf - special shape results in pore between the cells for gas exchange
Leaf palisade cell - packed full of chloroplasts for photosynthesis.
Sperm cell - tail for swimming, head contains genes from the father and the middle contains mitochondria for energy.
Variety of Living Organisms 1
PLANTS (e.g. Maize, Peas)
- Contain chloroplasts to carry out photosynthesis.
- Cellulose cell walls.
- Store carbohydrates as starch.
ANIMALS (e.g. Insects, Worms)
- Can´t carry out photosynthesis.
- No cell walls.
- Store carbohydrates as glycogen.
Variety of Living Organisms 2
FUNGI (e.g. Moulds, Yeast)
- Multicellular or Unicellular.
- Contain many nuclei.
- Chitin cell wallls.
- Saprotrophic nutrition.
BACTERIA (e.g. Lactobacillus, Pneumococcus)
- Single-celled organisms. C
- Contain a circular chromosome of DNA instead of a nucleus.
- Some can carry out photosynthesis.
Cell Structures 2
Nucleus - controls the activity of the cell, contains the DNA.
Cytoplasm - where chemical reactions take place.
Cell Membrane - controls what goes into and out of the cell.
Chloroplasts - contain chlorophyll (which absorbs sunlight) and where photosynthesis takes place.
Vacuole - mainly contains water and dissolved sugars/amino acids.
Variety of Living Organisms 3
PROTOCTISTS (e.g. Algae, Protozoa)
- Single-celled organism.
- Some have plant and animal cell features
VIRUSES (e.g. Influenza, HIV)
- They are parasites. Reproduce only in living cells.
- Have a protein coat.
- Contain one type of nucleic acid (DNA or RNA)