B1 cells and organisation Flashcards Preview

biology > B1 cells and organisation > Flashcards

Flashcards in B1 cells and organisation Deck (23):
1

what is a light microscope

a microscope that uses a beam of light to form an image of an object

2

what is an electron microscope

a microscope that uses a beam of electrons to form an image and can magnify up to 2,000,000 times which lets you see the subcellular structures inside cells

3

what is the equation for calculating image size

magnification x size of real object

4

what happens in diffusion when SA:V ratio gets smaller

gases and food molecules can no longer reach every cell by simple diffusion
metabolic waste cannot be removed fast enough to avoid poisoning the cells

5

name adaptations for exchanging materials

1) large surface area
2) thin membrane (short diffusion path)
3) efficient blood supply- maintains steep concentration gradient

6

what is diffusion

process that allows dissolved substances to pass through the cell membrane (enter or exit cell)

7

what process is it that moves from high concentration to low concentration

diffusion and osmosis

8

what factors speed up the rate of diffusion

bigger the difference in concentration gradient

increase in temperature

increase in surface area

9

what is osmosis

when water molecules move across a partially permeable cell membrane

10

what is isotonic

when the concentration of solutes in the solution outside the cell is the same as the internal concentration

11

what is hypertonic

when the concentration of solutes in the solution outside the cell is higher than the internal concentration

12

what is hypotonic

if the concentration of solutes in the solution outside the cell is lower than the internal concentration

13

what is turgor

pressure that makes cells hard and rigid

14

what is plasmolysis

when water is lost by osmosis and the vacuole and cytoplasm shrink and the cell membrane pulls away from the cell wall. these cells die quickly unless osmotic balance restored

15

what is active transport

when the substances needed by a cell have to be moved against a concentration gradient across a partially permeable membrane

16

which process moves from low concentration to high

active transport

17

how can the rate of active transport increase?

if a cell respires and releases a lot of energy

18

how does active transport take place in plants

allows root hair cells to absorb mineral ions from very dilute soil solutions

19

how does active transport take place in humans

allows sugar molecules used for respiration to be absorbed from lower concentrations in gut to higher concentrations in blood

20

what is a eukaryotic cell

a cell that has a cell membrane, cytoplasm and genetic material in a nucleus e.g. animal, plant, fungi and protista

21

what is a prokaryotic cell

single called living organism that had a single dna loop found free in the cytoplasm e.g. bacteria

22

what is a plasmid and what is its function

small rings of dna code for specific features e.g. antibiotic resistance. used in genetic engineering to carry new genes into the genetic material of other organisms

23

what is glycogen

a chemical used in cellular respiration by the mitochondria to transfer energy needed for fibres to contract