Structures / Functions of Living Organisms

Question 1

Mrs Gren H

Answer 1

Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrient, Homoeostasis

Question 2

what is Homoeostasis?

Answer 2

control of internal conditions (like temperature or water content)

Question 3

function of nucleus

Answer 3

controls cell and stores genetic material

Question 4

Cell membrane does?

Answer 4

controls what enters / leaves the cell

Question 5

what is the Cytoplasm? Function?

Answer 5

gel-like substance where chemical reactions happen

contains enzymes

Question 6

what are Chloroplasts ?

Answer 6

site of photosynthesis

contain green chlorophyll

Question 7

what is the Cell wall in plants?

Answer 7

supports and strengthens the cell

made of cellulose

Question 8

what is the function of the Vacuole ?

Answer 8

contains sap (sugars and salts)

Question 9

Describe Plants

Answer 9

multi cellular
have chloroplasts to photosynthesise
have cell walls made from cellulose
store carbs as sucrose or starch

Question 10

Describe Animals

Answer 10

multi cellular
nervous coordination
store carbs as glycogen

Question 11

Describe Fungi

Answer 11

some single celled 
others have body of mycelium made of hyphae (nuclei)
cells walls made from chitin 
saprotrphic excretion 
stores carbs as glycogen

Question 12

what is a pathogen ?

Answer 12

an organism that can cause a disease

Question 13

examples of pathogens

Answer 13

protocist :plasmodium, causes malaria
bacteria :pneumococcus, causes pneumonia
virus :influenza virus, causes flu and HIV

Question 14

what is a catalyst

Answer 14

substance which increases speed of reaction without being changed or used up in the reaction

Question 15

what are enzymes

Answer 15

biological catalyst
used to speed up metabolic reactions in body
enzymes are all proteins

Question 16

why is the shape of enzymes important?

Answer 16

has active site - part substrate joins enzyme
only speed one reaction as substrate must be correct shape to fit active site
this is called ‘lock and key’ model

Question 17

what is a substrate?

Answer 17

molecule changed in a reaction

Question 18

what is the right temperature for enzymes ?

Answer 18

optimum temperature (reaction goes fastest) for human enzymes is 37°C

Question 19

what happens to enzymes when too hot?

Answer 19

at first increases rate of reaction as more heat = more energy = more collision
if too hot, bond holding enzymes break
this makes enzyme lose shape and can’t fit substrate so is denatured, this is irreversible

Question 20

what happens to enzymes when too cold?

Answer 20

low temperatures means less energy = less collision so slower reaction until they get so cold they become inactive

Question 21

what happens to enzymes when the pH isn’t right?
what is the optimum pH?
do all enzymes work best at this pH?

Answer 21

pH interferes with bonds holding enzymes, changes shape and can denature it
usually optimum pH is neutral 7
pepsin (breaks proteins in stomach) works best at pH 2 to be well suited for acid conditions

Question 22

Define Diffusion

Answer 22

the net (overall) movement of particles from an area of high concentration to an area of low concentration

Question 23

What does diffusion happen in?

Simplest type of diffusion…

Answer 23

happens in liquids and gases as their particles move

simplest type is when gases diffuse through each other (like perfume into air)

Question 24

How / what substances move through cell membrane?

Answer 24

substances move through cell membrane by diffusion, osmosis and active transport
only small molecules can diffuse (like glucose)
bigger molecules can’t fit (like starch)

Question 25

Define osmosis

Answer 25

net movement of water molecules from a high water concentration to a low water concentration across a partially permeable membrane

Question 26

what is a partially permeable membrane ?

Answer 26

membrane with small holes in it

cell membrane are partially permeable

Question 27

What direction do water molecules go during osmosis?

How is water controlled in/out of cell

Answer 27

water molecules move randomly, some go both ways

tissue fluids surround cell so if cell needs water/has too much, it can become more/less dilute

Question 28

what is turgor pressure ?

Answer 28

when contents of cell push against cell wall (plants) which helps support and helps support plant

Question 29

describe a turgid cell

Answer 29

plump swollen cell (healthy)

holds shape of cell with turgor pressure

Question 30

describe a flaccid cell

Answer 30

cell without enough water and turgor pressure

inelastic cell wall keeps cells structure in position but cell becomes droopy

Question 31

Define active transport

Answer 31

movement of particles against a concentration gradient (like low concentration to high concentration) using energy released during respiration

Question 32

How is active transport used in the gut?

Answer 32

high concentration of nutrients from gut diffuse naturally into blood
sometimes lower concentration in gut, so active transport takes place to allow nutrients go in blood
this stops us from starving

Question 33

what are the factors of diffusion/osmosis/active transport rates?
what means faster?

Answer 33

surface area to volume ratio - larger surface area to ratio means faster
temp - hotter it is = more energy = faster
concentration gradient - bigger concentration difference means faster (not active transport)

Question 34

What changes rate of diffusion?

Answer 34

concentration difference (higher concentration difference = faster diffusion)

Question 35

Describe protocists

Examples?

Answer 35

single celled microscopic
have nucleus
some have chloroplasts (chlorella)
some animal like (amoeba)

Question 36

Describe bacteria

Examples?

Answer 36

single celled microscopic 
no nucleus 
plasmid contains DNA
some photosynthesise
Lactobacillus / Pneumococcus

Question 37

Describe viruses

Examples ?

Answer 37

can only reproduce in living cells (depend so parasite)
protein coat around some genetic material
Influenza virus

Question 38

what does urine contain?

Answer 38

urea, water and salts