Characteristics & classification
What 7 characteristics do all living organisms share?
- they move
- they respire
- they respond to their internal and external environment
- they grow and develop
- they reproduce
- they excrete their waste
- they require nutrition
State 3 parts of an animal cell visible under a light microscope
Nucleus, cytoplasm and the cell membrane
Define diffusion
The net movement of molecules from an area of high concentration to an area of low concentration down their concentration gradient
What chemical elements are present in carbohydrates?
Carbon, hydrogen, oxygen (C,H,O)
What is a catalyst?
A substance which increases the rate of reaction without being used up or changed itself
Define respiration
The chemical reactions in cells that break down nutrient molecules and release energy for metabolism
What is the function of ribosomes?
Ribosomes are the site of protein synthesis
Where does the energy for the movement of particles in diffusion come from?
From the kinetic energy of the particles that causes them to move in random directions
How do you test for starch?
Add iodine to the sample
Describe the structure of enzymes
Enzymes are proteins that contain a highly specific active site that fits a specific substrate
Define excretion
The removal of the waste products of metabolism and substances in excess of requirements
A very metabolically active cell is likely to have lots of which type of organelle?
Mitochondria as they produce energy through aerobic respiration
How does temperature affect the rate of diffusion?
As the temperature increases, so does the rate of diffusion as the particles have more kinetic energy and move faster
Describe the structure of DNA
- It is a polymer made of many nucleotide monomers
- It is made of 2 strands in the shape of a double helix
- Each strand contains bases (A, T, C, G)
- The 2 strands are linked between the bases
Why are enzymes necessary in biological systems?
They speed up reactions so that less energy is needed for the reaction to occur
What are the 5 kingdoms?
Animal, Plant, Fungus, Prokaryote, Protoctist
Name 3 organ systems in the body
- The respiratory system
- The circulatory system
- The reproductive system
Give one use of water in the body
Water is used as a solvent in the body
How do the bases in DNA pair up?
A always pairs with T
C always pairs with G
State 4 factors that affect the rate of an enzyme-controlled reaction
- Temperature
- pH
- Substrate concentration
- Enzyme concentration
What is the difference between monocotyledons and dicotyledons
Monocotyledons only contain one embryonic flower (cotyledon) whereas dicotyledons contain two
How do you convert from microm to mm?
Divide by 1000
E.g. 6 microm = 0.006mm
What happens if you place an animal cell in a hypotonic solution?
There is a net movement of water into the cell which causes the animal cell to burst (lysis)
How do you test for Vitamin C?
Add DCPIP to the solution drop by drop until the solution permanently changes colour
If temperature increases above the optimum, how does this affect enzyme function?
The active site will be distorted as the enzyme denatures and so it will no longer fit the substrate