cell structure

Question 1

nucleus

Answer 1

contains genetic material dna

Question 2

cell membrane

Answer 2

control which substances can pass ina nd out of the cell

Question 3

cytoplasm

Answer 3

where chemical reactions take place

Question 4

mitochondria

Answer 4

provide cells with the enrgy thye need to function it is also a site of an aerobic respiration

Question 5

ribosomes

Answer 5

site of protein synthesis

Question 6

cell wall

Answer 6

provides supportand structure

Question 7

vacuole

Answer 7

contains cell sap (sugars, salts, water)

Question 8

chloroplast

Answer 8

photosynthesis absord light energy

Question 9

what organellas does bacteria have

Answer 9

bacteria is a prokaryotic cell, it contains cytoplasm, cell wall, cell membrane, ribosomes, genetic material is a single strand of dna ( some have plasmids = extra genes)
flagella = tail that helps bacteria move around

Question 10

equation fro magnification

Answer 10

magn = image size/ object size

Question 11

What is the pathway of light through a microscope?

Answer 11

Light source ➔ stage ➔ microscope slide ➔ object ➔ objective lens ➔ body tube ➔ eyepiece lens ➔ eye

Question 12

light miscroscopes pros

Answer 12

easy to use
relatively cheap

Question 13

light micsrospe cons

Answer 13

rely on light
resolution is limited = 2ym
any detail less than 0.2 ym will appear blurray
not good enogh to study subcellural

Question 14

electrical microspoes pros

Answer 14

use elctrons instead of light
maximum resolution is 0.1nm
can use them to study sub cellular

Question 15

electrical microscopes cons

Answer 15

very expensive
hard to use

Question 16

Multicellular organisms, like ourselves, require a continuous supply of new cells.
What are the three reasons why new cells are required?

Answer 16

Growth (we need more cells as we grow)
Development (we need new cell types as we develop new tissues)
Repair (we need to replace the cells that we lose each day)

Question 17

What is the cell cycle?

Answer 17

The series of steps that take place as a cell grows and then divides

Question 18

Steps of the cell cycle

Answer 18

Cellular growth - the cell gets larger and produces more sub-cellular structures, such as mitochondria and ribosomes.
DNA replication - chromosomes duplicate, so that each consists of two arms (copies).
More cell growth.
Mitosis - the DNA divides into two.
Cytokinesis - the cell divides into two.

Question 19

Steps of mitosis & cytokinesis

Answer 19

DNA condenses to form chromosomes.
Chromosomes line up along the centre of the cells.
Cell fibres pull the two arms of each chromosome to opposite sides (poles) of the cell.
Cytokinesis - the entire cell divides to form two identical daughter cells.

Question 20

before a bacteria cell can divide it need to do 2 main things

Answer 20

grow
replicate genetic material

Question 21

for optimal growth bacteria

Answer 21

warm
moist
plenty of neutrients

Question 22

Once a bacterial cell has grown and replicated its genetic material, it is ready to divide by binary fission.

Describe the stages of this process

Answer 22

The two circular strands of DNA move to opposite sides of the cell

A new cell wall from down the middle of the cell

The two halves pull apart to form two cells

Question 23

2 key features of stem cell

Answer 23

• able to differentiate into specalised cells
  divide by mitosis

Question 24

key feautre of embryonic stem cells

Answer 24

they can differentiate into any type of cells

Question 25

Name the two types of stem cells found in animals.

Answer 25

Adult stem cells Embryonic stem cells

Question 26

Where in the body are adult stem cells found?

Answer 26

Bone marrow

Question 27

What do we call the plant tissues that are continually growing and that contain stem cells?

Answer 27

Meristems

Question 28

what are adaptations of sperm cells

Answer 28

Flagellum - allows the sperm cell to swin though the uterus and fallopian tube to reach the egg lots of mitochondria - provides energy needed to swim digestive enzymes at the tip = used to break a hole into the egg when the sprem reaches it half as much genetic material as normal adult cellIt is streamlined to make swimming easier

Question 29

what is diferentiation

Answer 29

a process by which a normal cell becomes specialised

Question 30

describe 3 main conditions that are casued by faulty cells

Answer 30

type 1 diabetes: - damage to thepancrease cells that normally produce insulin paralysis - sometimes caused by damaged nerve cells sickle cell anremia: - caused by misshapen red blood cells

Question 31

how to treat the faulty cells

Answer 31

1. extract embryonic stem cells from early embryis 2. grow them in a labratory 3. stimualate them to differentiate into whichever type of specialised cell that we want 4.then give them to the patient to replace their faulty cells

Question 32

what are some drawbacks of embryonic treatment

Answer 32

The embryonic stem cells must come from embryos. These are in limited supply, and some people have ethical objections to it, as they think the embryos could have developed into a person. The cells could be rejected by the person's immune system as it would identify them as foreign.

Question 33

an alt for embryoinic treamtend

Answer 33

use adult stems ( taken from patient themself) won't cause rejection can only differentiate into different types of blood cell can only treat sickle cell anamei

Question 34

rissksof using stem cells in medecine

Answer 34

1. virus transmition 2. tumor develompent

Question 35

what is an ethical issues with stem cells

Answer 35

an embryo has a potential for human life

Question 36

what si a diffusion

Answer 36

diffusion is the net movement of particles froman area of high concentration to area of low concentration

Question 37

what is a passive process

Answer 37

doesn't require any energy from the cell

Question 38

3 factors that affect the rate of diffusion

Answer 38

concentration gradient - larger the conc gradient = higher the rate of diffusion tempeture - higher temp give particles more kinetic energy = they will move faster = diffuse more quickly surface area - larger SA = higher rate of diffusion

Question 39

defenition for osmosis

Answer 39

osmosis i net movement of water molecules across a partially permable membrane from a region of higher water concentration to a regionof lower water concentration

Question 40

What would happen to red blood cells if they were placed in pure water?

Answer 40

Great! If placed in pure water, then the water concentration would be higher outside the cell (in the pure water) than inside the cell. This means that water would move down its concentration gradient into the cell, causing it to swell and possibly burst.

Question 41

what is active transport

Answer 41

it is a net movememnt of particles foma rea of lower conc to area of high concentration. movement of molecules against their conc gradient

Question 42

2 things that active transport reqiures

Answer 42

- energy from the cell (mitochondria) - cell membrane

Question 43

things single celled organisms need to a sord and get rid of to survive:

Answer 43

absorb : oxygen glucose amino acids get rid of waste: carbon dioxide

Question 44

key fact about SA to V

Answer 44

SA to V ratio decreases as organisms get larger

Question 45

why are specilised exchnage surface

Answer 45

they increase ourSA to V ration by giving us Extra SA

Question 46

diffusion distance

Answer 46

distance that molecules would have to diffuse to get from the outide of their body to the inside of their body, ass the oraganisms get larger the diffusion distace insrease massivly therefore te diffusion will be slower

Question 47

differenc ebetween transport systems and exchange systems

Answer 47

exchange systems get substances in and out of their bodies transport systems - transport those substances to the parts of thir bodies that need them

Question 48

Give two examples of exchange surfaces in humans and describe their function.

Answer 48

Example 1 - Alveoli (or lungs) Example 1 - Alveoli allow oxygen and carbon dioxide to diffuse in and out of the body/bloodstream Example 2 - Villi (or small intestines) Example 2 - Villi allow nutrients such as glucose, amino acids, mineral ions etc to be absorbed from the small intestines into the bloodstream

Question 49

What is an exchange surface?

Answer 49

A part of an organism over which substances are exchanged with the environment

Question 50

State and explain fivehjjl features that most exchange surfaces have in common.

Answer 50

Feature 1 - Large surface area Explanation 1 - Lots of molecules can diffuse across at the same time Feature 2 - Surfaces are very thin Explanation 2 - Substances only have to diffuse a short distance Feature 3 - Surfaces are permeable Explanation 3 - Substances are able to pass through the surface Feature 4 - Good blood supply (good supply of 'internal medium') Explanation 4 - Maintains a strong concentration gradient as blood is constantly replaced Feature 5 - Good supply of 'external medium' Explanation 5 - Maintains a strong concentration gradient as the air or food etc is constantly replaced

Question 51

State and explain three features of alveoli that make them good exchange surfaces.

Answer 51

Feature 1 - There are lots of alveoli, giving a large total surface area Explanation 1 - Lots of molecules can diffuse across at the same time Feature 2 - Surfaces are very thin (only 1 alveolar cell and 1 capillary cell thick) Explanation 2 - Substances only have to diffuse a short distance Feature 3 - Surfaces are permeable Explanation 3 - Oxygen and carbon dioxide are able to diffuse across Feature 4 - Good blood supply (good supply of 'internal medium') Explanation 4 - Maintains a strong concentration gradient as blood is constantly replaced Feature 5 - Good supply of air ( good supply of 'external medium') Explanation 5 - Maintains a strong concentration gradient as the air in the alveoli is constantly replaced with new oxygen rich air from the atmosphere