transport in cells

Question 1

diffusion definition

Answer 1

the spreading out of particles which results in a net movement from an area of high concentration to an area of low concentration

Question 2

what can diffuse through cell membranes

Answer 2

only very small molecules can diffuse through cell membranes through things like oxygen, glucose,amino acids and water. big molecules like starch and proteins can’t fit through the membrane

Question 3

what can the rate of diffusion be affected by

Answer 3

the concentration gradient - the bigger the concentration gradient. the faster the rate of diffusion. this is because the net movement from one side is greater
temperature - the higher the temp the faster the rate of diffusion. this is because the particles have more energy so move around faster
surface area - the larger the surface area, the faster the rate of diffusion as more particles can pass through at once

Question 4

osmosis definition

Answer 4

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

Question 5

whats a partially permeable membrane

Answer 5

its just one with very small hole in it. so small in fact only tiny molecules like water can pass through them and bigger molecules e.g. sucrose, a sugar can’t

Question 6

osmosis is a type of what

Answer 6

diffusion

Question 7

whats the practical for investigating the effect of sugar solutions on plant cells

Answer 7

cut a potato into identical cylinders and measure their masses
get some beakers w different sugar solutions in them. one should be pure water and another should be very concentrated sugar solution. then a few others with concentrations in between
place one potato cylinder in each beaker leave them in for 24 hours
take cylinders out dry then measure masses
if the cyclinders have drawn water by osmosis theyll have increase mass if water dawn out theyll decrease in mass

Question 8

whats the dependent variable for investigating the effect of sugar solutions on plant cells

Answer 8

cylinder mass

Question 9

whats the independent variable for investigating the effect of sugar solutions on plant cells

Answer 9

concentration of the sugar solution

Question 10

whats control variables for investigating the effect of sugar solutions on plant cells

Answer 10

volume of solution, temp, time, type of sugar used

Question 11

what errors may happen in investigating the effect of sugar solutions on plant cells

Answer 11

if potato cylinders r not fully dried the excess water would give a higher mass, or if water evaporated from the beakers, the concentrations of the sugar solutions would change

Question 12

active transport definition

Answer 12

its the movement of particles against a concentration gradient i.e from an area of lower concentration to an area of higher concentration using energy transferred during respiration

Question 13

what does active transport do

Answer 13

can be used to move substances in and out of cells. it allows cells to absorb ions from very dilute solution

Question 14

what does the root hair cell do

Answer 14

active transport

Question 15

hows active transport used in the gut

Answer 15

used in digestive system when there is a lower concentration of nutrients in the gut but a higher concentration of nutrients in the blood.
when higher concentration of glucose and amino acids in gut diffuse naturally in blood, but sometimes theres a lower concentration of nutrients in the gut than there is in the blood.
active transport allows nutrients to be taken into the blood,despite the fact that the concentration gradient is the wrong way. essential to stop starving - glucose can be taken into bloodstream -> glucose then transported to cells where its used for respiration

Question 16

true or false cells cannot absorb ions from very dilute solutions

Answer 16

false cells can absorb ions from very dilute solutions

Question 17

why do plants need to take up mineral ions

Answer 17

they are essential to healthy growth

Question 18

why do root hair cells need to use active transport to take mineral ions from up the soil

Answer 18

the concentration of mineral ions inside the root hair cells is greater than in the soil/they are taking up mineral ions against the concentration gradient

Question 19

name one molecule that is taken up by active transport in the gut

Answer 19

glucose or sugar

Question 20

how to calculate volume

Answer 20

volume = length x width x height

Question 21

how to calculate area

Answer 21

area = length x width

Question 22

how do u calculate surface area

Answer 22

calculate the area of each side and add them all together

Question 23

what are 4 things exchange surfaces are adapted for `

Answer 23

they have a thin membrane so substances only have a short distance to diffuse - substances have a short diffusion pathway
large surface area so lots of substances can diffuse at once
exchange surfaces in animals have lots of blood vessels to get stuff in + out of blood quickly
gas exchange surfaces in animals are often ventilated too - air moves in and out

Question 24

name 4 adaptations of alveoli

Answer 24

an enormous surface area about 75msquared in humans
a moist lining for dissolving gases
very thin walls
a good blood supply

Question 25

whats the job of the lungs

Answer 25

is to transfer oxygen to the blood and to remove waste CO2 from it. to do this the lungs contain millions of little air sacs called alveoli where gas exchange takes place

Question 26

whats the alveoli surrounded by

Answer 26

network of tiny blood vessels

Question 27

where does air enter + leave the alveoli by

Answer 27

bronchioles

Question 28

3 adaptations of villi

Answer 28

a single layer of surface cells
increase surface area
very good blood supply to assist quick absorption

Question 29

explain gas exchanges in leaves

Answer 29

plants need CO2 for photosynthesis. CO2 diffuses into the air spaces within the leaf, then diffuses into the cells where photosynthesis happens. Underneath of the leaf is an exchange surface. Its covered in little holes called stomata which CO2 diffuses in through. O2 + water vapour also diffuses through the stomata

Question 30

explain water loss in plants

Answer 30

water vapour is lost from all over the leaf surface but most of it is lost through the stomata. if plant is losing water faster through its leaves than it can be replaced by the roots of the stomata can be closed by guard cells. without guard cells plant would lose so much water that it would wilt

Question 31

explain gas exchange in fish

Answer 31

theres a lower concentration of oxygen in water than in air. so fish have special adaptations to get enough of it. in a fish, the gas exchange surface is the gills

Question 32

what do gills do

Answer 32

water (containing O2) enters the fish through its mouth and passes out through the gills. as this happens oxygen diffuses from water into blood in gills + CO2 diffuses through the blood into water

Question 33

structure of gills

Answer 33

each gill is made of lots of thin plates called gill filaments which give a large surface area for exchange of gases. the gill filaments are covered in lots of tiny structures called lamellae which increase surface area

Question 34

what do the lamallea do

Answer 34

lots of blood capillaries to speed up diffusion between the water and the blood. they also have a thin surface layer of cells to minimise the distance that the gases have to diffuse