Cells, stem cells

Question 1

Nucleus

Answer 1

• Contains DNA in 46 chromosomes, encloses genetic material.
• Controls all activities in the cell.

Question 2

Cytoplasm

Answer 2

-Where most of the chemical reactions take place.

Question 3

Cell membrane

Answer 3

-Controls substances entering and exiting the cell

Question 4

Mitochondria

Answer 4

• The powerhouse of the cell

- Where aerobic respiration takes place, giving energy to the cell.

Question 5

Ribosome

Answer 5

• Where protein synthesis takes place

- Makes the proteins needed for the cell.

Question 6

Cell wall

Answer 6

-Strengthens the plant cell and gives it support.

Question 7

Vacuole

Answer 7

• A space in the plant cell cytoplasm filled with cell sap.

- Keeps the plant cell rigid.

Question 8

Chloroplast

Answer 8

• Absorbs light for photosynthesis

- Green colour because it contains chlorophyll.

Question 9

Eukaryotic cells

Answer 9

• More complex organisms
• Multicellular
• Have a true nucleus in the cytoplasm, enclosing the genetic material.

Question 10

Prokaryotic cells

Answer 10

• Single cell organisms (bacteria kingdom)
• Do not have a true nucleus in the cytoplasm.
• Much smaller than eukaryotic cells.

Question 11

Plasmid

Answer 11

A circular DNA molecule found in prokaryotic cells.

It is different to chromosomes.

Question 12

Order of magnitude

Answer 12

If you are comparing two numbers (size of two objects) to find the order or magnitude :
Bigger number / smaller number

Question 13

Nerve cell adaptions

Answer 13

• Can be very long cell (up to 1 meter), which enables it to carry an impulse a long distance.
• The dendrites (branches) help to catch signals.
• The axon is covered in a ‘fatty layer’. This is said to help transmit the signal quicker, as well as providing insulation.

Question 14

Muscle cell adaptions

Answer 14

• The mitochondria produce large amounts of ATP, which is required for actions inside the cell.
• glucose is needed for energy.
• Myoglobin is in muscle cells. This stores oxygen until it is required for respiration and other cellular actions.

Question 15

Sperm cell adaptions

Answer 15

• Acrosome- The head contains enzymes in the nucleus.used for penetrating the female egg.
• The midpiece has a central core with many mitochondria spiralled around it, for the journey through to the egg.
• The tail or “flagellum” propels the cell and make it move quickly.

Question 16

Root hair cell adaptions

Answer 16

• large surface area to speed up osmosis.
• They don’t have chloroplasts because they are underground and get any light.
• It’s huge vacuole keeps it rigid and increases its surface area massively.

Question 17

Xylem cells adaptations

Answer 17

• The hollow tubes act like pipes allowing water and dissolved minerals to flow through them.
• They have a strengthened cell wall to allow the water to flow through.
• They develop from pipe shapes cells arranged end to end, and the cytoplasm in the pipes dies, allowing the cell to be hollow, and water to flow through.

Question 18

Phloem cells adaptations

Answer 18

• Phloem tubes are hollow to carry food substances like sugar produced in leaves during photosynthesis to every part of the plant.
• The cell walls between adjoining cells develop holes like a sieve allowing transport through the tube.
• Companion cells provide nutrients and carry out all of the cellular functions of a sieve-tube element in plants.

Question 19

Embryonic stem cells

Answer 19

The cells taken from an early state embryo. These can develop into over 200 cell types of the adult body.

Question 20

Adult stem cell

Answer 20

Adult stem cells maintain and repair the tissue in which they are found in e.g. Stem cells found in bone marrow can treat disorders from the bone marrow.

Question 21

Pluripotent cell

Answer 21

A cell that can give rise to any mature cell type, a stem cell.

Question 22

Stem cell definition.

Answer 22

An undifferentiated cell which is capable of giving rise to any mature type of cell, and can differentiate into any mature cell type.