Topic 1 - Cell Biology

Question 1

What are eukaryotic cells?

Answer 1

Eukaryotic cells are complex and include animal and plant cells.

Question 2

What are prokaryotic cells?

Answer 2

Prokaryotic cells are small and simple. Eg bacteria

A prokaryote is a prokaryotic cell.

Question 3

What is the function of the nucleus?

Answer 3

Contains genetic material and controls activities of the cell

Question 4

What is the function of cytoplasm?

Answer 4

Gel-like substance where most chemical reactions happen. Contains enzymes which control these reactions.

Question 5

What is the function of cell-membrane?

Answer 5

Holds the cells together and controls what goes in and out.

Question 6

What is the function of mitochondria?

Answer 6

Where respiration takes place

Question 7

What is the function of ribosomes?

Answer 7

Where proteins are made in the cell

Question 8

What is the function of the cell wall?

Answer 8

Made of cellulose. Supports the cell and strengthens it.

Question 9

What is the function of the vacuole?

Answer 9

Contains cell sap, a weak solution of sugar and salts.

Question 10

What is the function of chloroplasts?

Answer 10

Where photosynthesis takes place.

Contains lots of chlorophyll which is needed to absorb light for photosynthesis.

Question 11

Do bacteria cells contain a nucleus?

Answer 11

No, instead they have a single strand of DNA.

They also have other small rings of DNA called plasmids.

Question 12

Why do we use microscopes?

Answer 12

Microscopes let us see things that we cant see with the naked eye.
They let us see individual cells and sub cellular structures.

Question 13

Whats the difference between a light microscope and electron microscope?

Answer 13

Light microscopes use light and lenses to magnify an image.

Electron microscopes use electrons instead of light and have a a much higher magnification and resolution.

Question 14

Whats the definition of resolution?

Answer 14

Resolution is the ability to distinguish between 2 points.

A higher resolution gives sharper images.

Question 15

Whats the formula for magnification?

Answer 15

Magnification = Image size / Real size

Question 16

What is the process by which cells become specialised for its job?

Answer 16

Differentiation

Question 17

What does most differentiation occur?

Answer 17

As an organism develops.

Question 18

What are undifferentiated cells called?

Answer 18

Stem cells.

Question 19

Whats the function and features of sperm cells?

Answer 19

Function of sperm is to get male DNA to female DNA.

Has a long tail and streamlined head to help it swim to the egg.
Lots of mitochondria in the cell to provide energy needed.
Carries enzymes in its head to digest through the egg cell membrane.

Question 20

Whats the function and features of nerve cells?

Answer 20

Function is to carry electrical signals from one part of the body to another.

Cells are long and have branched connections to form a network throughout the body.

Question 21

Whats the function and features of muscle cells?

Answer 21

Function is to contract quickly.

They are long (more space to contract) and contain lots of mitochondria to generate the energy needed to contract

Question 22

What is the function and features of root hair cells?

Answer 22

Function is to absorb water and mineral ions from the soil.

They grow into long hairs which give the plant a larger surface area

Question 23

What is the function and features of xylem and phloem cells?

Answer 23

Function is to transport substances such as food and water around the plant.

To form tubes, the cells are long and joined end to end.
Xylem cells are hollow and phloem have few sub cellular structures.

Question 24

What contains genetic information?

Answer 24

Chromosomes

Question 25

How many pairs of chromosomes does a human cell have?

Answer 25

23 pairs

Question 26

What are the steps of the cell cycle?

Answer 26

1) DNA spreads out 2) Cell grows and increases in sub cellular structures 3) It duplicates its DNA and forms X-shaped chromosomes 4) Chromosomes line up at center of cell and cell fibres pull them apart. Two arms of each chromosome go to opposite ends of the cell. 5) Membranes form round each of the sets of chromosomes. They become nuclei of 2 new cells. 6) Lastly, cytoplasm and cell membrane divides .

Question 27

How do prokaryotic cells replicate?

Answer 27

Through binary fission

Question 28

What are the steps for binary fission?

Answer 28

1) DNA and plasmids replicate 2) Cell gets bigger and the 2 circular DNA strands move to opposite ends. 3) Cytoplasm begins to divide and new cell walls begin to form 4) Cytoplasm divides and 2 new cells are produced.

Question 29

What are functions of stem cells?

Answer 29

Medicine: Adult stem cells transferred from bone marrow of healthy person can replace faulty blood cells in a person that receives them. Embryonic stem cells can be used to replace faulty cells in sick people. Eg insulin producing cells for diabetics. Therapeutic cloning where embryo is made to have same genes as patient so stem cells wouldnt get rejected.

Question 30

What is a risk of using stem cells in medicine?

Answer 30

Stem cells grown in a lab could become contaminated with a virus and spread onto the patient.

Question 31

What are some reasons people have as to why they are against stem cell research?

Answer 31

1) They feel human embryos shouldnt be used for experiments as they are potential life.(Counter is that curing existing patients who are suffering is more important)(Embryos used are usually unwanted ones) 2) Scientists should concentrate more on finding and developing other source of stem cells, so theres no need to use embryos.

Question 32

How can stem cells be used to clone plants?

Answer 32

In plants, stem cells are found in the meristems. These stem cell can be used to produce clones of plants quickly and cheaply. It may be ideal for a farmer to get desired features like disease resistance.

Question 33

What is diffusion?

Answer 33

Diffusion is the spreading out of particles from an area of higher concentration to an area of lower concentration.

Question 34

What increases diffusion rate?

Answer 34

How big the concentration gradient (difference in concentrations) is. Temperature

Question 35

What is osmosis?

Answer 35

Osmosis is the movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of lower water concentration.

Question 36

What is a partially permeable membrane?

Answer 36

A membrane with very small holes in it. Only tiny molecules like water can pass through and not big molecules like sucrose.

Question 37

What is active transport?

Answer 37

Active transport is when substances are absorbed AGAINST a concentration gradient eg from lower to higher concentration.

Question 38

How does active transport work for plants?

Answer 38

Allows plants to absorb minerals from a very dilute solution to a highly concentrated solution. Active transport needs energy from respiration to work.

Question 39

How does active transport work in humans?

Answer 39

Allows nutrients to be taken into the blood from the gut even if fhe gut has a lower concentration. Example of the nutrient is glucose

Question 40

What depends of Surface Area : Volume ?

Answer 40

How easy it is for an organism to exchange substances with irs environment.

Question 41

Why can single celled organisms diffuse substances straight into the cell?

Answer 41

They have large surface area compared to volume

Question 42

What are adaptations of exchange surfaces?

Answer 42

Thin membrane - Short distance for substances to diffuse. Large surface area - Lots of a substance can diffuse at once. Lots of blood vessels - Get stuff into and out of blood quickly. Ventilated - Air moves in and out

Question 43

How does gas exchange happen in the lungs?

Answer 43

Alveoli in the lungs are specialised to maximise diffusion of O2 and CO2. They have large surface area. Moist lining for dissolving gases. Thin walls. Good blood supply

Question 44

How does gas exchange work in the small intestine?

Answer 44

Small intestine inside is covered with millions of villi. They increase surface area so digested food is absorbed more quickly into the blood. They have single layer of surface cells. Good blood supply to assist quick absorption.

Question 45

How does gas exchange happen in leaves?

Answer 45

Stomata on the underneath of a leaf allow CO2 in and O2 and water vapour out. Stomata size is controlled by guard cells which adapts to how juch water is being lost. Flattened shape of leaf increases area of exchange surface. Air spaces inside leaf also increase area of surface so more chance of CO2 getting into cells.

Question 46

How does has exchange work in fish?

Answer 46

Gills is the gas exchange surface. Water (containing oxygen) goes into mouth and passes out through gills. Each gill is made up of gill filaments with big surface areas. Gill filaments have lots of lamellae which increase surface area even more. Lamellae have lots of blood capillaires to speed up diffusion. Also have thin surface layer of cells to minimise distance. Blood and water flow in opposite directions. Blood through lamellae and water over lamellae. Maintains large concentration gradient.