Topic 1 - Cells

Question 1

What are living things made of ?

Answer 1

Cells

Question 2

Eukaryotic Cell

Answer 2

A cell with a membrane bound nucleus (Eg. Plants and Animals)

Question 3

Prokaryotic Cell

Answer 3

A cell without a membrane bound nucleus (Eg. Bacteria)

Question 4

What is the difference between a Eukaryotic and Prokaryotic Cell ?

Answer 4

Eukaryotic have a nucleus whilst Prokaryotic cells have free DNA and rings of DNA called plasmids

Question 5

What is the size difference between a Eukaryotic and Prokaryotic cell

Answer 5

Eukaryotic cells are 100x larger

Question 6

What are the differences between and animal and plant cell

Answer 6

Plant cells have; a vacuole filled with cell sap, chloroplasts for photosynthesis, a cell wall for structural integrity

Question 7

Roles of chloroplast, mitochondria and ribosomes

Answer 7

Chloroplast - Site of photosynthesis
Mitochondria - Site of respiration
Ribosome - Site of protein synthesis

Question 8

Roles of nucleus, cell membrane and cytoplasm

Answer 8

Nucleus - stores genetic information
Cell Membrane - Controls what goes in and out the cell
Cytoplasm - the site of chemical reactions

Question 9

Roles of the cell wall, vacuole and flagellum

Answer 9

Cell wall - maintains the structure of the cell
Vacuole - contains cell sap (a mixture of dissolved ed sugar)
Flagellum - allows cells to move more efficiently

Question 10

What is differentiation?

Answer 10

When a cell becomes specialised to a certain role

Question 11

When does differentiation happen?

Answer 11

Animals - at the early stages of embryo development
Plants - at any point within their lives

Question 12

What is a specialised cell? (and example)

Answer 12

A cell that has been adapted to enable it to complete a specific job (Eg. Sperm cell, Root hair cell)

Question 13

How have sperm, nerve and muscle cells been adapted to their function?

Answer 13

Sperm - Lots of mitochondria to provide energy for the swimming and a flagellum to move faster.
Nerve - Surrounded by insulation (myelin sheith) to ensure electrical impulses stay in the cell
Muscle - Can change shape to contract and relax

Question 14

How have root hair cells, the xylem and phloem adapted to their function?

Answer 14

Root hair - Long hair like structures to increase SA for absorbing nutrients from the soil
Xylem - Hollow cells to transport water
Phloem - companion cells to provide energy for active transport and sieve plates

Question 15

What is magnification ?

Answer 15

Magnification is the ability of the microscope to make an object appear larger

Question 16

What is resolution ?

Answer 16

The detail which can be seen in a magnified object, higher resolution means more detail.

Question 17

What is the difference between a light and electron microscope ?

Answer 17

Electron - Much higher resolution and higher magnification so sub cellular structures can be seen
Light - Cheaper

Question 17

Total magnification calculation

Answer 17

Total magnification = eye piece lens x objective lens

Question 18

How thick should a specimen on a slide be ?

Answer 18

As thin as possible - ideally 1 cell thick

Question 19

Why should specimens be as thin as possible ?

Answer 19

So that light can pass through the cell so we can see inside it.

Question 20

Why do we use iodine to stain the cells ?

Answer 20

The stain helps us differentiate between the sub-cellular structures of the cell

Question 20

How do you draw cells ?

Answer 20

No shading
Straight lines
Note down the magnification
Annotate what you can see

Question 21

What is the process of making an onion cell ?

Answer 21

1) Place a thin sample on a slide (1 cell thick)
2) Add a drop of iodine
3) Carefully add cover slip at an angle to avoid bubbles

Question 22

What is a micrometer ?

Answer 22

1/1000th of a millimetre

Question 23

What is the equation that links magnification, image size and actual size?

Answer 23

magnification = image size / actual size

Question 24

Difference between adult and embryonic stem cells

Answer 24

Adult - can only differentiated into certain types of cells Embryonic - Can differentiate into any type of cell

Question 25

What are stem cells ?

Answer 25

Undifferentiated cells

Question 26

Where are stem cells found in plants ?

Answer 26

Meristem tissue - tips of roots and shoots

Question 27

Where are stem cells found in humans ?

Answer 27

Bone marrow

Question 28

Uses of stem cells in plants and animals

Answer 28

Animals - treating disease using bone marrow and therapeutic cloning Plants - Produces lots of identical crops to prevent extinction.

Question 29

Whta is therapeutic cloning ?

Answer 29

When an embryo is produced with the same genes as the patient, so they can be used for medical treatment without rejection

Question 30

Risks of using stem cells

Answer 30

Viral diseases can be spread and there are ethical issues involving embryos.

Question 31

What are chromosomes ?

Answer 31

Long stands of DNA

Question 32

Where are chromosomes found ?

Answer 32

In the nucleus

Question 33

Describe the 3 stages of the cell cycle

Answer 33

Stage 1: cell grows, DNA replicates and sub cellullar structures multiply. Stage 2: Chromosomes and copies line up down centre of the cell and are pulled to either side. New nuclear membranes form. Stage 3: cytoplasm divides and new cell membranes form.

Question 34

What is the purpose of mitosis

Answer 34

The growth and repair of tissues

Question 35

What are the products of mitosis ?

Answer 35

Two identical daughter cells (clones)

Question 36

What causes cancer ?

Answer 36

Uncontrolled cell division

Question 37

What are benign tumours ?

Answer 37

Abnormal growth of cells contained in one area which do not invade neighbouring tissues.

Question 38

What are malignant tumours ?

Answer 38

Cancerous growths which invade neighbouring tissues and can spread to other parts of the body to form secondary tumours.

Question 39

How does cancer spread ?

Answer 39

Parts of tumours which aren't restricted to a membrane break off and travel through the bloodstream.

Question 40

What can increase the chance of cancer ?

Answer 40

Genetics and Lifestyle

Question 41

What is diffusion ?

Answer 41

The movement of particle form an are of high concentration to low concentration

Question 42

Examples of diffusion in plants and animals

Answer 42

Plants - CO2 diffuses into the leaf, O2 diffuses out Animals - O2 diffuses from lungs to blood, CO2 diffuses from blood to lungs

Question 43

What 3 things can increase the rate of diffusion ?

Answer 43

1) Temperature 2) Surface area 3) Concentration gradient

Question 44

How do you work of the the surface area to volume ratio ?

Answer 44

Surface area / volume

Question 45

How are single cell organisms adapted for diffusion ?

Answer 45

High surface area to volume ratio so all parts of the cell are close to the outside, short diffusion pathway.

Question 46

What is exchange in cells ?

Answer 46

Substances diffusing in and out of cells

Question 47

Why do multicellular organisms need specialised exchange systems ?

Answer 47

They have small SA:V so need organs to bring substances from outside to the internal cells.

Question 48

What are the three features of gills, lungs and the small intestine ?

Answer 48

Large surface area, lots of blood vessels and thin membranes

Question 49

How do these feature help with diffusion?

Answer 49

Large surface area - lots of diffusion at once. Thin membranes - short diffusion pathway/distance. Lots of blood vessels - maintain a concentration gradient.

Question 50

What is osmosis ?

Answer 50

The movement of water molecules from a dilute solution to a concentrated solution through a partially permeable membrane.

Question 51

What happens in dilute solutions ?

Answer 51

They absorb water by osmosis and expand. Animal cells will burst.

Question 52

What happens in concentrated solutions

Answer 52

Water leaves the cells by osmosis and they will shrink

Question 53

What happens to a plant tissue in a dilute solution ?

Answer 53

It will gain mass and length

Question 54

What happens to plant tissue in a concentrated solution ?

Answer 54

It will lose mass and length

Question 55

How do you find percentage change in mass ?

Answer 55

change in mass / starting mass x 100

Question 56

What is active transport ?

Answer 56

The movement of particles from an area of low concentration to an area of high concentration.

Question 57

What are the differences between diffusion and active transport?

Answer 57

Active transport requires energy Active transport goes against a concentration gradient

Question 58

Active transport in plants (example)

Answer 58

Some mineral ions are absorbed against the concentration gradient.

Question 59

Active transport in humans (example)

Answer 59

Glucose is absorbed from the small intestine into the blood