B1 Cells and Organisation

Question 1

The Nucleus

Answer 1

Contains the DNA.

Question 2

The cytoplasm

Answer 2

Where chemical reactions take place

Question 3

Cell Membrane

Answer 3

Controls the passage of substances such as glucose and mineral ions into the cell. It also controls the movement of substances such as urea or hormones out of the cell

Question 4

Mitochondria

Answer 4

Structures in the cytoplasm and where respiration takes place. They release energy for the cell. Very small 1-2 micro metres in length. 0.2-0.7 micro metres in diameter

Question 5

Ribosomes

Answer 5

Where protein synthesis takes place

Question 6

Cell Wall

Answer 6

Provides strength and support

Question 7

Large permanent vacuole

Answer 7

Contains a store of food called cell sap. Keeps the cell rigid to support the plant

Question 8

Chloroplasts

Answer 8

Trap sunlight energy for photosynthesis. Are green and contain chlorophyll.

Question 9

Eukaryotic cells

Answer 9

Include all animal and plant cells. Many organelles. Nucleus is present. Larger cells (10 micro metres to 100 micro metres). DNA is linear (many chromosomes). Multicellular.

Question 10

Prokaryotic cells

Answer 10

All bacteria cells. Very few organelles. No nucleus. Extremely small cells ( less than 2 micrometers in diameter. DNA is held in small circular, strands called plasmids and there is only one chromosome. Single cellular. Replicate by binary fission.

Question 11

Sperm Cells

Answer 11

For reproduction. Long tail and streamlined head for swimming. Lots of mitochondria for energy. Enzymes in the head to digest through the egg cell membrane.

Question 12

Nerve cells

Answer 12

Rapid signalling. Carry electrical signals from one part of the body to another. Have branched connections to form a network by connecting with other nerve cells.

Question 13

Muscle cells

Answer 13

For contraction. Long and lots of mitochondria. Help support and move the bones.

Question 14

Root hair cells

Answer 14

Absorbing water and minerals. Big surface area for absorbing water and mineral ions from the soil.

Question 15

Phloem and xylen cells

Answer 15

Transporting substances. Form tubes. Cells are long and joined end to end

Question 16

Diffusion

Answer 16

Diffusion is the spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.

Question 17

What is osmosis

Answer 17

Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

Question 18

Factors affecting the rate of diffusion

Answer 18

Difference in concentration. The temperature. The surface area of the memebrane

Question 19

What is active transport

Answer 19

Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). This requires energy from respiration.

Question 20

Active transport in plants

Answer 20

Active transport allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil. Plants require ions for healthy growth.

Question 21

Active transport in the gut with sugar

Answer 21

It also allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration. Sugar molecules are used for cell respiration.