Cell Biology

Question 1

What is a cell?

Answer 1

The smallest unit of life that can live on its own. They make up all living organisms and their tissues

Question 2

What are the differences between eukaryotic and prokaryotic cells?

Answer 2

• Eukaryotic cells are much larger than prokaryotic cells
• Eukaryotic cells contain membrane-bound organelles, while prokaryotic cells do not
• Eukaryotic cells keep their DNA in the form of chromosomes within a nucleus, whilst prokaryotic cells have their DNA loose in the cell

Question 3

Name 5 sub-cellular organelles found in both animal and plant cells

Answer 3

Cell membrane, ribosomes, mitochondria, nucleus, cytoplasm

Question 4

What is the cell membrane and what is its role

Answer 4

The cell membrane is a protective barrier around the outside of the cell which controls the movement of substances in and out of the cell.

Question 5

What is the cytoplasm and what is its role?

Answer 5

The cytoplasm is a jelly-like liquid that fills the cell. It allows substances to dissolve and is where chemical reactions take place

Question 6

What is the role of the nucleus?

Answer 6

It contains the genetic material of the cell and controls what the cell does.

Question 7

What is the role of the mitochondria?

Answer 7

To do aerobic respiration and make energy for the cell

Question 8

What is the role of the ribosomes?

Answer 8

Makes protiens that are used in antibodies, hormones and enzymes

Question 9

Name 3 organelles that are found in plant cells and not in animal cells

Answer 9

Vacuole, Cell wall, Chloroplasts

Question 10

In plants, what is the cell wall made of?

Answer 10

Cellulose

Question 11

What is the role of the plant cell wall?

Answer 11

Provides strength for the cell, preventing it from bursting / shrinking when water enters or leaves the cell via osmosis

Question 12

What does the permanent vacuole contain?

Answer 12

Sap

Question 13

What is the role of the permanent vacuole?

Answer 13

Supports the cell, maintaining its turgidity (shape)

Question 14

What is the role of the chloroplasts?

Answer 14

The site of photosynthesis - they make glucose for the cell

Question 15

What are chlorophyll?

Answer 15

A green pigment within chloroplasts that absorbs sunlight for photosynthesis - they are why plants are green

Question 16

Name 7 organelles that are found in bacterial cells

Answer 16

Cell wall, Cell membrane, Cytoplasm, Nucleoid (Circular strand of DNA), Plasmids, Ribosomes, Flagella (Not in every bacterial cell)

Question 17

What are plasmids, and what is their role?

Answer 17

Small, circular loops of DNA that are separate from the main strand. They contain ‘extra genes’ that are sometimes useful to bacteria, such as antibacterial resistance

Question 18

What is the prokaryotic cell wall composed of?

Answer 18

Peptidoglycan

Question 19

What are the 5 kingdoms of life?

Answer 19

Animals, Plants, Protoctists, Fungi, Bacteria

Question 20

What kingdoms of life are eukaryotic?

Answer 20

Animals, Plants, Fungi, Protoctists

Question 21

What is the defining feature of a eukaryote?

Answer 21

DNA in the form of chromosomes, found inside a nucleus

Question 22

Are viruses living organisms?

Answer 22

No

Question 23

What are heterotrophs?

Answer 23

Organisms that eat other plants or animals for energy and nutrients

Question 24

What are autotrophs?

Answer 24

Organisms that are capable of making their own food from chemicals in the environment

Question 25

What are saprotrophs?

Answer 25

Animals that eat dead or decaying organims

Question 26

What are the steps of saprotrophic nutrition?

Answer 26

1. Bacteria/fungi secreting enzymes out of their cells into the soil or dead organism. 2. The enzymes digest the organic material. This is known as extracellular digestion as it happens outside the cells. 3. The products of digestion are absorbed by the bacteria/fungi.

Question 27

Are fungi harmful to humans?

Answer 27

Yes, they can cause conditions such as athelete's foot or ringworm, but can also cause infections that can be very hard to treat

Question 28

What are mycelium and hyphae?

Answer 28

Hyphae are thread like structures in fungi, that are organised into a system called mycelium

Question 29

Are fungi unicellular, multicellular, or both?

Answer 29

Most fungi are multicellular, but they can be unicellular as well

Question 30

Are protoctists unicellular, multicellular, or both?

Answer 30

Unicellular

Question 31

Give an example of a protoctist that can photosynthesise

Answer 31

Unicellular algae

Question 32

Give an example of a protoctist that consumes other organisms to get energy

Answer 32

Amoebas

Question 33

Are protists harmful to humans?

Answer 33

Yes

Question 34

What is a parasite?

Answer 34

Organisms that live in, on or with another organism (host). They feed, grow or multiply in a way that harms their host. However, they need their host for their survival.

Question 35

Are viruses harmful to humans?

Answer 35

Yes, but only the ones that can infect humans

Question 36

3 reason why multicellular organisms require a continuous supply of new cells

Answer 36

Growth, Development and Repair

Question 37

Describe the cell cycle

Answer 37

- a series of steps that take place as a cell grows and then divides - happens in nearly every cell in the body - produces 2 identical daughter cells - only one division - steps: 1) DNA condenses to form chromosomes 2) chromosomes line up along the equator (centre) of the cell 3) cell fibres pull the two arms of the chromosomes to opposite poles of the cell 4) cytokenisis - the entire cell splits to form identical daughter cells

Question 38

Which type of organism divides by binary fission?

Answer 38

Bacteria

Question 39

describe binary fission?

Answer 39

- the process by which bacteria divide and reproduce - asexual - bacteria must grow and replicate its genetic material before it can divide - steps: 1) grows and reproduces genetic material 2) 2 circular strands of DNA move to opposite sides of the cell 3) new wall forms down the middle of the cell 4) the two halves pull apart - while both cells produced will have the loop of DNA, plasmids are randomly located, so often the produced cells will not have exactly the same genetic material

Question 40

Which 3 conditions do bacteria require for fast growth?

Answer 40

Warmth, moisture, nutrients

Question 41

What is a stem cell?

Answer 41

A cell that can speciate into any other type of cell - undifferentiated There are 2 main types: embryonic and adult 2 main features: can divide by mitosis to form more cells, can differentiate into specialised cells In plants, they are found in meristem tissue, at the tips of roots and shoots (stem cells found in plants at all stages during the plant's life)

Question 42

What is the main difference between embryonic and adult stem cells?

Answer 42

Adult stem cells can only differentiate into a few other types of cell, whereas embryonic stem cells can differentiate into any type of specialised cell

Question 43

What diseases can be treated using stem cells?

Answer 43

Sickle cell anaemia - to replace the faulty blood cells Paralysis - to replace the faulty nerve cells Type 1 diabetes - to replace the faulty pancreatic cells

Question 44

Describe stem cell treatment

Answer 44

- Steps: 1) extract stem cells from an early embryo 2) grow these cells in a lab 3) stimulate differentiation into whatever is required 4) inject them into the patient - drawbacks: Any mutations could be transferred to the patient, ethical issues around the life the embryo could have lived, any viruses within the stem cell, could divide too rapidly and form a tumour within the patient - advantages: won't be rejected by the patient's body

Question 45

3 uses of plant stem cells

Answer 45

1: can be used to produce clones of plants quickly and cheaply, rather than being grown from seeds 2: therefore being used to grow rare plants 3: produce clones with desired features

Question 46

What is diffusion?

Answer 46

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

Question 47

What is osmosis?

Answer 47

movement of water across a partially permeable membrane from an area of high concentration to an area of low concentration

Question 48

4 main factors affecting rate of diffusion?

Answer 48

concentration gradient temperature surface area diffusion distance

Question 49

What happens if you place a plant cell in a very salty solution vs a beaker of pure water?

Answer 49

salty solution: water will move from the cell to the surrounding solution, causing the cell to become plasmolysed pure water: the cell will become turgid as water molecules move from the water to the cell