B1

Question 1

Order of units

Answer 1

1 km = 1000 m
1 m = 100 cm
1 mm = 1000 micrometers
1 micrometer = 1nm

Question 2

Light vs electron microscopes

Answer 2

Light has lower resolution and magnification
Light is b & w, electron is colour
Light is 2D, electron is 3D
Electron needs specialist training
Light is smaller

Question 3

How to work out total magnification

Answer 3

Multiply the magnification of eyepiece lens by the magnification of the objective lens

Question 4

Magnification equation

Answer 4

Image size = magnification x size of real object

Question 5

What is resolution

Answer 5

The ability to distinguish between two points

Question 6

What is resolving power

Answer 6

Affects how much detail it can show

Question 7

Structures in animal cell

Answer 7

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes

Question 8

What does the nucleus do

Answer 8

Controls all the activities in the cell and contains the genes on the chromosomes that carry the instructions for making proteins needed to build new cells or organisms

Question 9

What is the cytoplasm

Answer 9

Liquid gel in which organelles are suspended and where chemical reactions for life take place

Question 10

What is the cell membrane

Answer 10

Controls the passage of substances such as glucose and mineral ions into the cell. Controls movement of substances such as urea or hormones out of the cell

Question 11

What is mitochondria

Answer 11

Where aerobic respiration takes place

Question 12

What are ribosomes

Answer 12

Where protein synthesis takes place

Question 13

What is cell wall

Answer 13

Made of cellulose that strengthens the cell and gives it support

Question 14

What are chloroplasts

Answer 14

Contain the substance chlorophyll which absorbs light so the plant can make food by photosynthesis

Question 15

What is a permanent vacuole

Answer 15

Filled with cell sap which keeps the cell rigid to support the plant

Question 16

What are eukaryotic cells

Answer 16

Have a cell membrane, cytoplasm and genetic material enclosed in a nucleus. All animals, plants, fungi and protista are eukaryotes

Question 17

Example of prokaryote

Answer 17

Bacteria

Question 18

Size of prokaryotic cell vs eukaryotic cell

Answer 18

Prokaryotic is much smaller

Question 19

Structures in prokaryotic cell

Answer 19

Cytoplasm, cell membrane, cell wall (no cellulose), genetic material is in a free loop found in cytoplasm, may have plasmids, many have slime capsule, some have flagellum

Question 20

Adaptations of nerve cells

Answer 20

• lots of dendrites to make connections to other nerve cells
• axon that carries nerve impulse from one place to another (very long)
• synapses are adapted to pass the impulses to another cell or between a nerve cell and a muscle using transmitter chemicals
• contain lots of mitochondria to provide energy needed to make transmitter chemicals

Question 21

How do striated muscle cells work

Answer 21

Striated (striped) muscle cells work together in a muscle tissue, muscles contract and relax in pairs to move skeleton so vertebrates can move

Question 22

How do smooth muscle cells work

Answer 22

Form one of the layers of tissue in the digestive system and contract to move gut

Question 23

Adaptations of striated muscle cells

Answer 23

• contain special proteins that slide over each other making the fibres contract
• contain many mitochondria to transfer energy needed for chemical reactions that take place
• can store glycogen (broken down and used in cellular respiration)

Question 24

Sperm cell adaptations

Answer 24

• long tail
• mitochondria
• digestive enzymes
• large nucleus with genetic information

Question 25

Adaptations of root hair cells

Answer 25

- big surface area available for water to move into the cell - large permanent vacuole which speeds up movement of osmosis from soil to cell - many mitochondria for active transport

Question 26

Adaptations of photosynthetic cells

Answer 26

- contain chloroplasts - positioned in continuous layers in the leaves and outer stem to absorb as much light as possible - large permanent vacuole to keep cell rigid as a result of osmosis (support stem and spread out leaves)

Question 27

Adaptations of xylem cells

Answer 27

- are alive when originally formed by spirals of lignin form and kill cell, results in long hollow tubes - spirals and rings of lignin in the xylem make them very strong and able to withstand pressure of water movement

Question 28

Role of xylem cells

Answer 28

Carry mineral ions and water from roots across the plant

Question 29

Role of phloem

Answer 29

Carries food made by photosynthesis around the plant

Question 30

Adaptations of phloem

Answer 30

- cell walls between the cells break down and form a sieve plates which allow water carrying dissolved food to move freely - lose a lot of their internal structures but are supported by companion cells to keep them alive

Question 31

What is diffusion

Answer 31

Net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient until equilibrium is reached

Question 32

Relationship between diffusion rate and concentration gradient

Answer 32

Higher gradient = faster rate

Question 33

Relationship between temperature and diffusion

Answer 33

Higher temperature = faster rate

Question 34

Examples of diffusion in living things

Answer 34

- dissolved substances moving into and out of cells - oxygen and carbon dioxide in lungs and red blood cells and body cells

Question 35

What is osmosis

Answer 35

Net movement of water molecules form an area of high concentration to low concentration through a partially permeable membrane until equilibrium is reached

Question 36

What is a dilute sugar solution

Answer 36

High concentration of water and low concentration of sugar

Question 37

What is a concentrated sugar solution

Answer 37

Low concentration of water and high concentration of sugar

Question 38

What does it mean if solution is isotonic to the cell

Answer 38

Concentration of solutes in solution outside the cell is the same as the internal concentration so no movement

Question 39

What does it mean if the solution is hypertonic to the cell

Answer 39

Concentration of solutes in the solution outside the cell is higher than the internal concentration so water moves out of cell

Question 40

What does it mean if solution is hypotonic to the cell

Answer 40

The concentration of solutes in the solution outside the cell is lower than the internal concentration so water moves into cell

Question 41

What happens to cell in animal if it is hypotonic

Answer 41

Water moves in by osmosis so the cell swells and may burst

Question 42

What happens to cell in animal if it is hypertonic

Answer 42

Water will move out by osmosis and cell will shrivel up and no longer survive

Question 43

What happens when water moves into plant cells by osmosis (hypotonic)

Answer 43

Vacuole swells which presses the cytoplasm against the cell wall and the pressure builds up until no more water can physically enter the cell (turgid)

Question 44

What happens if solution is hypertonic to cell contents in plants

Answer 44

Water will leave by osmosis and the cells will no longer be firm (become flaccid) so it can no longer support plant tissues, vacuole and cytoplasm shrink and eventually the cell membrane pulls away from the cell wall (plasmolysis)

Question 45

What is active transport

Answer 45

When substances move against a concentration gradient

Question 46

What is required for active transport

Answer 46

Energy produced during cell respiration so cells in active transport usually have lots of mitochondria

Question 47

Examples of active transport importance

Answer 47

Mineral ions from soil into roots Sugar out of gut and kidney tubules into blood

Question 48

Surface area: volume ratio

Answer 48

Bigger organisms have smaller ratios so more difficult to exchange minerals - gases and food molecules can no longer reach all cells in body - metabolic waste cannot be removed fast enough

Question 49

Adaptations for exchanging materials

Answer 49

- large surface area - thin membrane (short diffusion path) - efficient blood supply moves diffusing substances away maintaining steep gradient - being ventilated makes gas exchange more efficient by maintaining steep gradient

Question 50

Example of adapted exchange surfaces in humans

Answer 50

Alveoli Villi

Question 51

Examples of adapted exchange surfaces

Answer 51

- large roots - flat, thin leaves

Question 52

Example of adapted exchange surfaces in fish

Answer 52

Gills exchanging blood and carbon dioxide between blood and water