Biology Unit 2 (2)

Front 1

What is polygenic inheritance?

Back 1

- When more than one gene is involved in influencing the phenotype.
- Genes will be at different locations (gene loci) on the chromosomes
- Variation in height for an age group is an example

Front 2

Characteristics of Golgi Apparatus

Back 2

- Stacks of curved membrane-bound sacs formed by fusion vesicles from the ER
- Modifies protein and packages it for transport

Front 3

Characteristics of Smooth Endoplasmic Reticulum

Back 3

- Like rER but has no attached ribosomes
- Makes lipids and steroids such as reproductive hormones
-

Front 4

Characteristics of Ribosomes

Back 4

- Made of RNA and protein
- Found in cytoplasm or attached to rER
- Site of proteinsynthesis

Front 5

Characteristics of Rough Endoplasmic Reticulum

Back 5

- Membrane bound flattened sacs
- Ribosomes attached to outer surface
- Proteins made by these ribosomes are transported through the ER to other parts of the cell

Front 6

What is the job of the nucleolus?

Back 6

- To make ribosomes

Front 7

Characteristics of Mitochondria

Back 7

- Inner membrane is folded to form cristae
- Site of later stages of aerobic respiration

Front 8

Characteristics of the Nucleus

Back 8

- Enclosed by an envelope (double membrane)
- Contains chromosomes
- DNA in the chromosomes contains genes that control the synthesis of proteins

Front 9

Characteristics of Lysosomes

Back 9

- Contain digestive enzymes
- Involved in the breakdown of unwanted structures in the cell

Front 10

Characteristics of Centrioles

Back 10

- Two hollow cylinders arranged at right angles to eachother
- involved in the formation of spindle fibres during nuclear division and in transport within the cytoplasm

Front 11

What are the two nucleus' that a pollen grain contains?

Back 11

- Tube nucleus
- Generative nucleus - on germination of the pollen it splits into two haploid gamete nuclei which move down the pollen tube

Front 12

What happens in fertilisation once the two male gamete nuclei reach the embryo sac?

Back 12

- One fuses with the egg cell and forms a diploid zygote
- Second fuses with the two polar nuclei in the embryo sac to form a triploid cell

Front 13

What is 'switching genes on'?

Back 13

- Cells become specialised because only some genes are switched on and produce active mRNA which is translated into proteins

Front 14

What switches an individual gene on or off in eukaryotes?

Back 14

- Enzyme RNA polymerase binds to the section on DNA adjacent to the gene to be transcribed, only when it has attached with transcription occur
- The gene remains switched off until the enzyme attaches successfully

Front 15

What is species richness?

Back 15

- The number of different species within an area at a particular time
- Measured by using quadrats in a random area, all the different species are counted and this is used as an estimate

Front 16

What is genetic diversity?

Back 16

- The genetic variation within a species
- Measured by finding the number of different alleles in a gene pool

Front 17

What is Endemism?

Back 17

- Where a species is found in only one particular area

Front 18

What are the three domains for taxonomic groupings?

Back 18

- Bacteria
- Archaea
- Eukaryota

Front 19

What is the niche of a species?

Back 19

- The way that it exploits its environment (eg. rabbits are a grassland herbivore)
- If two different species are present in the same niche there will be competition

Front 20

What are the three main types of adaptation?

Back 20

- Anatomical
- Behavioural
- Physiological

Front 21

What is anatomical adaptation?

Back 21

- A physical or structural adaptation, can either be internal or external

Front 22

What is behavioural adaptation?

Back 22

- A change in behaviour of an organism to increase its survival chances

Front 23

What is physiological adaptation?

Back 23

- Changes in the internal biochemical functioning of the organism in response to an altered environmental stimulus

Front 24

What is evolution?

Back 24

- The change in the frequency of certain alleles in a gene pool over time due to natural selection

Front 25

What are the roles of zoos in conserving endangered animals?

Back 25

- Education: Inform all age groups of various conservation issues such as the illegal trade of some animal products
- Scientific research: control of diseases etc
- Captive breeding programmes: Encourages endangered species to be bred
- Reintroduction programmes: release captive-bred animals back to the wild so populations can be maintained

Front 26

Describe how zoos maintain the genetic diversity of endangered species

Back 26

- Breeding programmes
- Careful selection of mates
- Use of genetic testing
- Can keep records

Front 27

Why are seeds stored in seed banks rather than living plants?

Back 27

- Take up less space so more species can be held
- Most plants produce lots of seeds so taking a few will not damage population
- Easier to store because they are dormant
- More cost effective

Front 28

How are seed banks used to conserve endangered plants?

Back 28

- Seeds collected from a number of different plants
- Xrayed to see if the contain fully formed embryos, meaning only seeds that can germinate are stored
- Dried to remove water, increases length of time can be stored
- Stored in the cold which also increases storage time
- Seeds are planted periodically to check theyll still grow

Front 29

What do plant cells have that animal cells dont?

Back 29

- Chloroplasts
- Amyloplasts
- Vacuole
- Cell wall

Front 30

What are the components of a cell wall?

Back 30

- Middle lamella: helps hold adjacent cells together
- Plasmodesmata and pits: Involved in cell-to-cell transport (The primary cell wall is still present in pits)

Front 31

Characteristics of sclerenchyma fibres

Back 31

- Short structures
- Ends Closed
- Tough lignin present in walls
- Used for support

Front 32

Characteristics of Xylem vessel

Back 32

- Long cylinders
- Ends are open
- Tough lignin present in walls as well as cellulose microfibrils
- Used for water and mineral transport and support
- Water only moves upwards due to the evaporation of water from the cells on the leaf surface

Front 33

What are nitrates used for in plants?

Back 33

- To supply nitrogen for making proteins, DNA, RNA and certain plant hormones

Front 34

What is calcium used for in plants?

Back 34

- To form calcium pectate in plant cell walls and to be involved in membrane permeability

Front 35

What is magnesium used for in plants?

Back 35

- helps the formation of DNA
- Used as an activator of certain plant enzymes

Front 36

Difference between the structures of starch and cellulose

Back 36

- Starch is made of alpha glucose units
- Cellulose is made up of beta glucose unit
- Starch contains branched molecules (amylopectin), cellulose does not

Front 37

What is the structure of an alpha glucose unit?

Back 37

-

Front 38

What is the structure of an beta glucose unit?

Back 38

-

Front 39

What is a cellulose microfibril?

Back 39

- Two parallel cellulose molecules joined by hydrogen bonds

Front 40

How are cellulose microfibrils arranged differently in primary and secondary cellulose cell walls?

Back 40

- Primary plant cell wall: microfibrils laid in criss-cross manner, lignin is never present in these cell walls
- Secondary plant cell wall: microfibrils laid in sheets with microfibrils only running in one direction only, lignin is present in these cell walls

Front 41

What is the function of starch in plants?

Back 41

- Energy storage molecule made up of a-glucose units which can be used in respiration

Front 42

What is the function of cellulose in plants?

Back 42

- Major component of plant cell walls formed by b-glucose units

Front 43

What is the function of cellulose microfibrils in plants?

Back 43

- Hydrogen bonds between fibrils make it strong
- The arrangement of fibrils and the glue that holds them together gives strength and flexibility to plant cell walls and also allows them to be fully permeable to water

Front 44

What is the function of fibres in plants?

Back 44

- (Xylem and sclerenchyma) give support
- Xylem allows transport of minerals and water due to lignin being strong and waterproof

Front 45

Why is using plant fibres and starch sustainable?

Back 45

- They are renewable as they come from plants which can be regrown
- Starch can be made into bio-plastic to replace oil-based plastics and plant fibres can be used for rope
- Both can be burned for heat energy

Front 46

What are the modern drug testing protocols?

Back 46

1. Three phase testing
2. Placebo
3. Double blind trial

Front 47

What are the Three phase testings in modern drug trials?

Back 47

Phase 1: Few healthy people used, range of doses
- used to check its safe and that it has the effect its meant to from animal tests
Phase 2: 100-300 patients with condition used
- to check it is patient safe and works on the right condition
Phase 3: 1000-3000 patients, usually involves double blind trial
- to collect as much data as possible including effectiveness compared to placebo and side effects

Front 48

What is a placebo in modern drugs trials?

Back 48

- Appears identical to the drug except it in chemically inactive

Front 49

What is a double blind trial in modern drug trials?

Back 49

- Patients randomly divided into two groups
- One group receives drug, other receives placebo
- Patients or people recording changes do not know who received the drug as this reduces chance of bias

Front 50

Differences and similarities between modern protocols of drug testing and William Witherings digitalis soup

Back 50

Similarities:
- Both isolated possible drug
- both initially tested on small number of patients
Differences:
- Only modern protocols test on animals, then on healthy people first
- Only modern protocols have double blind trials including a placebo