Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
50 Cards in this Set
- Front
- Back
|
What is polygenic inheritance?
|
- 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 |
|
|
Characteristics of Golgi Apparatus
|
- Stacks of curved membrane-bound sacs formed by fusion vesicles from the ER
- Modifies protein and packages it for transport |
|
|
Characteristics of Smooth Endoplasmic Reticulum
|
- Like rER but has no attached ribosomes
- Makes lipids and steroids such as reproductive hormones - |
|
|
Characteristics of Ribosomes
|
- Made of RNA and protein
- Found in cytoplasm or attached to rER - Site of proteinsynthesis |
|
|
Characteristics of Rough Endoplasmic Reticulum
|
- 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 |
|
|
What is the job of the nucleolus?
|
- To make ribosomes
|
|
|
Characteristics of Mitochondria
|
- Inner membrane is folded to form cristae
- Site of later stages of aerobic respiration |
|
|
Characteristics of the Nucleus
|
- Enclosed by an envelope (double membrane)
- Contains chromosomes - DNA in the chromosomes contains genes that control the synthesis of proteins |
|
|
Characteristics of Lysosomes
|
- Contain digestive enzymes
- Involved in the breakdown of unwanted structures in the cell |
|
|
Characteristics of Centrioles
|
- 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 |
|
|
What are the two nucleus' that a pollen grain contains?
|
- Tube nucleus
- Generative nucleus - on germination of the pollen it splits into two haploid gamete nuclei which move down the pollen tube |
|
|
What happens in fertilisation once the two male gamete nuclei reach the embryo sac?
|
- 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 |
|
|
What is 'switching genes on'?
|
- Cells become specialised because only some genes are switched on and produce active mRNA which is translated into proteins
|
|
|
What switches an individual gene on or off in eukaryotes?
|
- 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 |
|
|
What is species richness?
|
- 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 |
|
|
What is genetic diversity?
|
- The genetic variation within a species
- Measured by finding the number of different alleles in a gene pool |
|
|
What is Endemism?
|
- Where a species is found in only one particular area
|
|
|
What are the three domains for taxonomic groupings?
|
- Bacteria
- Archaea - Eukaryota |
|
|
What is the niche of a species?
|
- 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 |
|
|
What are the three main types of adaptation?
|
- Anatomical
- Behavioural - Physiological |
|
|
What is anatomical adaptation?
|
- A physical or structural adaptation, can either be internal or external
|
|
|
What is behavioural adaptation?
|
- A change in behaviour of an organism to increase its survival chances
|
|
|
What is physiological adaptation?
|
- Changes in the internal biochemical functioning of the organism in response to an altered environmental stimulus
|
|
|
What is evolution?
|
- The change in the frequency of certain alleles in a gene pool over time due to natural selection
|
|
|
What are the roles of zoos in conserving endangered animals?
|
- 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 |
|
|
Describe how zoos maintain the genetic diversity of endangered species
|
- Breeding programmes
- Careful selection of mates - Use of genetic testing - Can keep records |
|
|
Why are seeds stored in seed banks rather than living plants?
|
- 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 |
|
|
How are seed banks used to conserve endangered plants?
|
- 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 |
|
|
What do plant cells have that animal cells dont?
|
- Chloroplasts
- Amyloplasts - Vacuole - Cell wall |
|
|
What are the components of a cell wall?
|
- 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) |
|
|
Characteristics of sclerenchyma fibres
|
- Short structures
- Ends Closed - Tough lignin present in walls - Used for support |
|
|
Characteristics of Xylem vessel
|
- 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 |
|
|
What are nitrates used for in plants?
|
- To supply nitrogen for making proteins, DNA, RNA and certain plant hormones
|
|
|
What is calcium used for in plants?
|
- To form calcium pectate in plant cell walls and to be involved in membrane permeability
|
|
|
What is magnesium used for in plants?
|
- helps the formation of DNA
- Used as an activator of certain plant enzymes |
|
|
Difference between the structures of starch and cellulose
|
- Starch is made of alpha glucose units
- Cellulose is made up of beta glucose unit - Starch contains branched molecules (amylopectin), cellulose does not |
|
|
What is the structure of an alpha glucose unit?
|
-
|
|
|
What is the structure of an beta glucose unit?
|
-
|
|
|
What is a cellulose microfibril?
|
- Two parallel cellulose molecules joined by hydrogen bonds
|
|
|
How are cellulose microfibrils arranged differently in primary and secondary cellulose cell walls?
|
- 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 |
|
|
What is the function of starch in plants?
|
- Energy storage molecule made up of a-glucose units which can be used in respiration
|
|
|
What is the function of cellulose in plants?
|
- Major component of plant cell walls formed by b-glucose units
|
|
|
What is the function of cellulose microfibrils in plants?
|
- 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 |
|
|
What is the function of fibres in plants?
|
- (Xylem and sclerenchyma) give support
- Xylem allows transport of minerals and water due to lignin being strong and waterproof |
|
|
Why is using plant fibres and starch sustainable?
|
- 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 |
|
|
What are the modern drug testing protocols?
|
1. Three phase testing
2. Placebo 3. Double blind trial |
|
|
What are the Three phase testings in modern drug trials?
|
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 |
|
|
What is a placebo in modern drugs trials?
|
- Appears identical to the drug except it in chemically inactive
|
|
|
What is a double blind trial in modern drug trials?
|
- 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 |
|
|
Differences and similarities between modern protocols of drug testing and William Witherings digitalis soup
|
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 |
