Section 1 - Nature and Variety of Organisms Flashcards

Question

what are catalysts

Answer 1

-a substance that increases the speed of a reaction without being changed or used up by the reaction

Answer 2

- living things produce enzymes that act as biological catalysts - they reduce the need for high temperatures that might damage cells - there are only enzymes to speed up useful chemical reactions (metabolic reactions) - ENZYMES ARE PROTEINS made of amino acid chains that fold into unique shapes specific to their function

Answer 3

- ENZYMES ARE PROTEINS made of amino acid chains that fold into unique shapes specific to their function - every enzyme has an active site - a part where the substrate joins onto the enzyme - enzymes are specific to their substrate as the active site is adapted to the substrate shape so no other can fit (lock and key model)

Answer 4

a molecule changed in a reaction

Answer 5

TEMPERATURE - changes rate of enzyme-catalyzed reaction AT FIRST : temp increases rate as enzymes have more energy and move about more and are more likely to collide to form enzyme-substrate complexes HOWEVER: if too hot, bonds holding together enzyme break, deforming the active site shape and denaturing the enzyme (substrate cant dit) PH: if the ph is too high or low it affects bonds, changing active site shape and denatuing the enzyme All enzymes have an optimum temp and ph (usualy ph 7) in which they work best.

Answer 6

the net movement of particles from an area of higher concentration to an area of lower concentration (particles move down a concentration gradient)

Answer 7

- doesn't require energy - happens in liquids and gasses - bigger the difference in concentration, the faster the diffusion rate

Answer 8

- substances can move in and out of cells by diffusion, osmosis and active transport - only small molecules like glucose, amino acids, water, and oxygen can diffuse through, big molecules like starch and proteins cant fit - behaves just like in air with a concentration gradient. they move about randomly so they go both waves but the net (overall) movement is to the area of lower concentration

Answer 9

the net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration

Answer 10

a membrane with very small holes in it, so only timi molecules (like water) can go through example: cell membrane

Answer 11

- water moves into and out of cells by osmosis - tissue fluid surrounds the cells in the body. it is squeezed out of blood capillaries to supply cells - tissue fluid has different concentration to fluid inside the cell, so water will either move into or out of the cell by osmosis - if a cell is short of water then the solution inside is more concentrated, and the outside is dilute, so the water will move in by osmosis to even out the concentration gradient - if a cell has lots o water the solution inside will be more dilute and water will be drawn out of cell and into fluid by osmosis

Answer 12

the movement of particles against a concentration gradient (from area of lower concentration to area of higher) using energy released from respirTION

Answer 13

allows for nutrients to be taken into the blood despite the fact that concentration gradient is the wrong way. this stops us from starving in plants, it is used to get minerals from the soil (lower concentration) into the root hair cells (higher concentration)

Answer 14

1) SURFACE AREA TO VOLUME RATIO - the rate of diffusion, osmosis, and active transport is higher in cells with a larger surface area to volume ratio 2) DISTANCE - short distance means substances move in and out faster (example- cell membranes are really thin) 3) TEMPERATURE - as temperature increases substances move in and out of cells faster 4) CONCENTRATION GRADIENT - substances move in and out of a cell faster if there is a big difference in concentration between the inside and outside of the cell. this doesn't affect active transport