Cell Biology (B)(p1/2)

Question 1

What are the 3 stages of cell cycle

Answer 1

Growth

DNA replication and mitosis

-division (cytokinesis

Question 2

What happens during the growth stage of a cell?

Answer 2

There is an increased number of sub cellular structures (mitochondria )

Question 3

How many chromosomes do humans have?

Answer 3

46 (2 pairs of 23 from mom and dad)

Question 4

How does the cell prepare for division?(mitosis/ DNA replication)

Answer 4

DNA is coiled up into chromosomes

The cell duplicates each chromosome (attaching to the original cell) forming an X shape

Then all chromosomes line up along cell centre. The fibres from edge of the cell attach to the half of the chromosomes.
Forming cell fibres

that pull arms of chromosomes(half) opposite sides of cell. Called poles.

Question 5

What is cytokinesis?

Answer 5

Cell membrane and cytoplasm pull apart forming 2 daughter cells. Having the same DNA.being identical

Question 6

What are stem cells and why are they important?

Answer 6

Cells divided by mitosis which differentiate into specialised cells

Question 7

What are the stem cells in plants, adults and baby’s?

Answer 7

-baby[embryonic Stem cells] differentiate into any cell

-adult[adult stem cells] in bone marrow, differentiate into types of blood cells

-plant: found in meristems[ differentiate into all cells needed for plant. Lasting for life.

Question 8

What are specialised cells

Answer 8

•have specific role in body, containing specific shape and structure. So have specific amounts of different organelles

Question 9

Why is a sperm cell specialised? (3fts)

Answer 9

Flagellum: help cell swim through uterus & Fallopian tube to reach egg

Mitochondria: provide energy for cell

Digestive enzymes: break hole into egg

Question 10

What is differentiation?

Answer 10

Process cell changes to become specialised

Question 11

How can stem cells be used to treat disease?(4stps)

Answer 11

(Stem cells replace fault cells with properly working cells)

1.extract embryonic cells from early embryos
2. Laboratory growth
3.stimulate into any cell
4. Give to patient to replace

Question 12

What are the risks of stem cell therapy?

Answer 12

1-embryonic stem cells are only cell to differentiate into any cell. Have limited supply and ethical issues

2- different genomes, destroying foreign cells, rejecting the cells.(can use medication to suppress, but not reliable.

3-transmit virus and chase tumours

Question 13

Why do people think we should not use stem cells?

Answer 13

-embryonic stem cells gave potential for human life(band in country’s)[embryo RIGHTS]
-although are from fertility clinics , unwanted.

Question 14

What is diffusion?

Answer 14

Diffusion is the net movement of particles to and area of higher concentration to an area of lower concentration

Through a partially permeable membrane to allow smaller molecules through.

NO ENERGY REQUIRED (passive process)

Question 15

What factors affect diffusion?(3)

Answer 15

-difference in concentration in 2 places (concentration gradient)larger= higher diffusion

-temperature. Higher moves faster and quicker.

-surface area: larger area =higher diffusion

Question 16

What is osmosis

Answer 16

The net movement of water molecules through a partir lay permeable membrane from a regien of higher water concentration to lower water concentration.

(Ratio of water:solutes determines concentration)

Question 17

What are solutes?

Answer 17

Dissolved sugars/salt in water.

Question 18

What is active transport?

Answer 18

The movement of molecules across a cell membrane from a region of lower concentration to region of higher concentration

( requiring energy from cellular respiration)

Question 19

Why does a plant need to use active transport?

Answer 19

There are higher concentration minerals in root hair cell than outside. So as they need minerals to survive. Will have to use energy for active transport

Question 20

What is surface area to volume ratio?

Answer 20

How big the surface area is compared to volume

(Bigger organism, surface area:volume decreases)

Higher SA:V are bacteria cells(rely on diffusion)

Low SA:V are humans( relay on specialised exchange surface)

Question 21

What are specialize exchange systems

Answer 21

Used in most multicellular organisms due to low surface area: volume

Question 22

What is a passive process?

Answer 22

A process that doesn’t require energy

Question 23

What is a hypotonic solution?

Answer 23

A solution with low solute concentration and high water concentration

Question 24

What happens when a potato is in a concentrated sugar / salty solution?

Answer 24

Water will leave the cell. So the mass will decrease