TOPIC 4: Natural Resources

Question 1

What organelles present in animal cells aren’t in plant cells?

Answer 1

centrioles

lysosomes

Question 2

What organelles do plant cells have that animal cells don’t?

Answer 2

cell wall;
vacuole and tonoplast;
chloroplasts;
pits;
plasmodesmata;
amyloplasts;
middle lamella

Question 3

Describe the structure of chloroplasts

Answer 3

biconvex shape;

double membrane

Question 4

Describe the function of chloroplasts

Answer 4

site of photosynthesis

Question 5

What are amyloplasts?

Answer 5

starch storage inside chloroplasts

Question 6

What’s the function of the vacuole?

Answer 6

waste, food and water storage;

turgor pressure supports plant

Question 7

What’s the tonoplast?

Answer 7

vacuole membrane

Question 8

What is the middle lamella made of?

Answer 8

pectin

Question 9

What’s the function of the middle lamella?

Answer 9

layer between cell walls which keep cells together for stability

Question 10

What are pits?

Answer 10

pores in cell walls that allow movement of fluid between cells

Question 11

What is plasmodesmata?

Answer 11

channels of cytoplasm through cell walls which transport substances between cells

Question 12

How are plasmodesmata formed?

Answer 12

ER trapped between newly divided cells at pits

Question 13

How are cellulose chains made?

Answer 13

condensation reaction between -OH groups on the 1st & 4th carbon on B-glucose, forming 1,4-glycosidic bond

Question 14

How do microfibrils form?

Answer 14

H bonds between -OH groups in neighbouring cellulose chains

Question 15

How is tensile strength related to the arrangement of cellulose?

Answer 15

many cellulose molecules;
criss-cross arrangement provides strength in both directions;
embedded in pectin and hemicellulose, which act as a glue - prevents sliding over each other

Question 16

What’s sclerenchyma?

Answer 16

ground tissue (dead cells) with rigid and thick lignified walls for plant support

Question 17

What’s parenchyma?

Answer 17

packing tissue providing mechanical support

Question 18

What’s phloem?

Answer 18

made of sieve tube elements & companion cells;

translocation of sugars and amino acids

Question 19

What are sieve tube elements?

Answer 19

living cells with perforated ends (sieve plates);
bidirectional flow;
few organelles

Question 20

What are companion cells?

Answer 20

has cytoplasms with solutes, providing substances for phloem & metabolic function;
pores for transport to phloem

Question 21

Describe the structure of xylem vessels

Answer 21

dead hollow cells from autolysis;
perforated ends so water can pass;
lignified secondary cell walls as well as cellulose cell wall;
pits that allow lateral movement

Question 22

What’s the function of xylem vessels?

Answer 22

transport of water and minerals

Question 23

What causes transpiration?

Answer 23

evaporation due to the hydrostatic pressure gradient;

higher pressure at the bottom of the plant

Question 24

Describe the process of transpiration

Answer 24

high WP in soil and low in root hair cell so water moves in by osmosis;
water travels up xylem (transpiration stream);
water diffuses out of stoma due to evaporation from sun;
water replaced by capillary action

Question 25

Why doesn't the transpiration stream break?

Answer 25

cohesion between water molecules due to dipole nature of water

Question 26

How are root hair cells adapted?

Answer 26

large SA due to hair-like projections

Question 27

Why is water important to plants?

Answer 27

transporting mineral ions (solvent properties); providing water to keep cells turgid (stability); photosynthesis; cooling the leaves

Question 28

What is nitrate used for in plants?

Answer 28

amino acids, chlorophyll, ATP

Question 29

What are the signs of a nitrate deficiency?

Answer 29

stunted growth, | yellow leaves

Question 30

What is magnesium used for in plants?

Answer 30

chlorophyll

Question 31

What are the signs of a magnesium deficiency?

Answer 31

yellow leaves

Question 32

What is phosphorus used for in plants?

Answer 32

DNA, | ATP

Question 33

What are the signs of a phosphorus deficiency?

Answer 33

purple leaves, | stunted growth

Question 34

What is calcium used for in plants?

Answer 34

cell wall; | membrane permeability

Question 35

What are the signs of a calcium deficiency?

Answer 35

stunted growth, especially at leaf margins

Question 36

Why can plant fibres be used for ropes and clothing?

Answer 36

long and thin, flexible, strong

Question 37

How are plant fibres extracted?

Answer 37

mechanically pulling out fibres; | digesting surrounding tissue (hemicellulose) by bacterial enzymes

Question 38

Why are biocomposites sustainable?

Answer 38

renewable - available for future generations; | biodegradable

Question 39

What are the disadvantages of plant fibres?

Answer 39

replace food crops; energy demanding in production and transport; don't always have the same desirable qualities

Question 40

What are the antibacterial properties of garlic?

Answer 40

allicin interferes with lipid synthesis and RNA production, killing bacteria

Question 41

Describe the stages of bacterial growth

Answer 41

1. lag phase - cells adjust to conditions by enzyme synthesis 2. log phase - cells divide exponentially 3. stationary phase - growth limited by factors 4. death phase - cell deaths > cells formed

Question 42

What are the ideal conditions for bacterial growth?

Answer 42

``` sufficient nutrients; optimum temperature; optimum pH; no build up of toxins; sufficient O2 for aerobic bacteria ```

Question 43

Describe Withering's drug development

Answer 43

1. potential substance identified 2. trial on a small group of people and then large 3. dosage refined due to near death 4. publication of treatise

Question 44

Describe the stages of modern drug development

Answer 44

1. active ingredient identified to be manufactured synthetically 2. pre-clinical testing in animals to assess safety 3. PHASE 1 trials - small group of healthy volunteers to assess absorption, digestion and doses 4. independent review of data 5. PHASE II trials - small group of patients to assess efficacy 6. PHASE III trials - large group of patients with placebo, random assignment and double blind trial 7. licensing for use

Question 45

What are the advantages of modern clinical trials?

Answer 45

fewer side effects, safer

Question 46

What are the disadvantages of modern clinical trials?

Answer 46

expensive, time-consuming

Question 47

What is a placebo and why is it used?

Answer 47

pill without the active ingredient; | control experiment to show that effect is due to the active ingredient

Question 48

Why is double blind testing used?

Answer 48

doctor and patient don't know who has the placebo; | avoids researcher from influencing outcome

Question 49

Why is random assignment used?

Answer 49

removes bias in assigning to a particular group

Question 50

What's an endosperm?

Answer 50

starch and lipid storage

Question 51

Which seeds are not endospermic?

Answer 51

dicotyledons - embryo absorbs stored nutrients and food is stored in the cotyledon

Question 52

What is the testa?

Answer 52

seed coat protecting embryo; | lignified outer ovule layer

Question 53

How do seeds germinate?

Answer 53

1. water taken in through pore in testa 2. metabolic changes triggered and plant growth substances are made 3. amylase breaks starch down into glucose and then sucrose for transport to radicle and plumule

Question 54

How is starch foam made?

Answer 54

1. water evaporates when heated, steam causes pressure to rise 2. seed explodes and starch gelatinises when it absorbs water 3. water creates bubbles in jelly, creating 3D foam

Question 55

What are the uses of starch?

Answer 55

paints, plasters, cloth treatment

Question 56

How are super-absorbents made?

Answer 56

made with chemically cross-linked starch