biology paper 1

magnification of the eyepiece x magnification of the objective lens

NUCLEUS: controls the cell and contains genetic material in the form of chromosomes

CYTOPLASM: where the most chemical reaction takes place

CELL MEMBRANE: a barrier that contains the passage of substances into and out of the cell

MITOCHONDRIA: contains the enzymes for cellular respiration and are the site of respiration 

CELL WALL: made from the cellulose provides structural support

VACUOLE: contains cell sap which provides support

CHLOROPLAST: contains chlorophyll site of photosynthesis

PROKARYOTES: have no nucleus for example bacteria

EUKARYOTES: have a nucleus, for example, a human cheek cell

DNA 

• DNA is a polymer
• it is made of two strands of nucleic acid
  
• the two strands are in the form of a double helix
• DNA is found in the nucleus

ENZYMES

• ENZYMES increase the rate of a chemical reaction
• are made of protein and the amino acid folds to make a shape into which the substrate can fit
  
• This is called the active site
• ENZYMES are denatured when they lose their shape

• temperature
  
• substrate concentration 
• PH
  
• enzyme concentration 

Cellular respiration 

• Happens inside the cell of all plants and animals
• It is an exothermic reaction

Aerobic respiration 

• Happens in almost all organism

GLUCOSE + OXYGEN              CARBON DIOXIDE + WATER + (ENERGY RELEASED)

Anaerobic respiration 

• In animal cells produces lactic acid

GLUCOSE              LACTIC ACID + (ENERGY RELEASED)

CARBON DIOXIDE + WATER                 GLUCOSE + OXYGEN

• It is an endothermic reaction
• photosynthesis occurs inside the chloroplast

Factors affecting photosynthesis 

• light intensity - increases the rate
• carbon dioxide - increases the rate
• temperature - decreases the rate 

Diffusion-  the net movement of particles from an area of high concentration to an area of low concentration along a concentration gradient

Active transport- molecules move against the concentration gradient from an area of low concentration to an area of high concentration. This requires ENERGY.

osmosis- the net movement of water from a dilute solution to a more concentrated solution through a partially permeable membrane

Mitosis- is the division of cells to produce new cells.

• parent cells contain chromosomes
  
• are copied
• chromatids pull apart
• two new cells are created each identical to the parent

Cell differentiation is when one cell changes into another type of cell. 

examples of specialised cells:

• root hair cell
• ovum (egg cell)
• Xylem
• sperm cell
• nerve cell

Stem cell are undifferentiated cells that can differentiate to form specialised cells 

Red blood cells

• Red blood cells carry oxygen
• they contain haemoglobin 
  
• they do not have a nucleus

Blood Vessels

• Artery, vein and capillary
  
• carry blood away from the heart

Plasma

transports:

• hormones
• antibodies
• nutrients 

formula :

the volume of water lost

              time