Bio Flashcards
1
Q
-giga
A
10^9
2
Q
Females
A
XX
3
Q
Males
A
XY
4
Q
Sex chromosomes?
A
Of the 23 pairs of chromosomes in the human cell - 1 is referred to as sex chromosomes
5
Q
Y chromosome?
A
Much smaller than X and contains fewer genes
Y gene contains genes needed to initiate male sexual development
6
Q
Sperm and egg
A
Sperm (of its 23 chromosomes) - 1 is either X or Y
Ovum - always contains X chromosome
7
Q
At fertilisation?
A
Sperm cell determines the sex of the resulting zygote
Thus it’s 50:50 ; ratio of males to females is 1:1
8
Q
Asexual reproduction
A
Parent plant produces a runner and new offspring develop along the length of the runner - divide by mitosis and differentiate into all cell types (genetically identical)
9
Q
Genetic variation
A
Reduces frequency of recessive inherited conditions
10
Q
Why are bacteria produced by binary fission (passing one loop of chromosomal DNA to each cell) not always genetically identical?
A
MUTATION MAY DEVELOP WHEN DNA COPIED (change in order of bases of DNA)
11
Q
Cells in this plant leaf?
A
Divide by mitosis to produce tiny plantlets ; they will eventually drop to the ground and grow into new plants - genetically identical
12
Q
Which type of human cell has no nucleus and thus no chromosomes?
A
MATURE red blood cells
13
Q
Alleles?
A
Dominant (capital letter)
Recessive (small letter)
14
Q
Genotype?
A
Alleles we have that control a characteristic
15
Q
Genotype?
A
Two alleles for each gene (1 from each parent) - genotype can be written as two letters with each letter representing one allele of the gene
16
Q
Phenotype?
A
Genes determine our phenotype but this can also be determined by environment
17
Q
Homozygous?
A
Two alleles of a gene that are the same
18
Q
Heterozygous?
A
Two different alleles of that gene
19
Q
If dominant allele present?
A
Allele always determines the phenotype
20
Q
Monohybrid cross
A
Cross between two individuals of a species where the impact of only a single gene is considered as a monohybrid cross
21
Q
When 50% is result of punnets square?
A
1:1
22
Q
Inheritance?
A
Genes and their alleles play a big role in determining our characteristics as genetic conditions (determined by alleles) can be passed down from one generation to the next
23
Q
For recessive conditions?
A
Heterozygous = carrier
Homozygous recessive = sufferer
24
Q
Expected probabilities of punnet squares not always seen?
A
Larger the sample size - more significant the expected probability
25
Height (continuous variation)
Example of a characteristic that is controlled by the action on more than one gene
26
If there is a mutation in the non-functional enzyme?
Phenotype is affected
27
Certain mutations
Very small effect on phenotype
28
Most mutations
No effect on phenotype - large sections of DNA on chromosomes do not code for proteins and these are unlikely to affect the phenotype
Silent mutations occur within a gene
Mutation changes base of DNA but not amino acids
Triplet code still codes for the amino acid
Mutation is silent because no effect on phenotyoe
29
Genetic engineering?
Copy of a gene from one organism and inserting that into DNA of another organism to create a genetically modified organism - TRANSGENIC
30
How does genetic engineering work?
Gene of interest cut from DNA of an organism using a restriction enzyme (breaks down phosphodiester bonds)
Restrictions enzymes cut DNA in a staggered way leaving short sections at the end of each gene - sticky ends
Bacterial plastic cut open using same restriction enzyme (same sticky ends that are
complementary to those on ends of gene)
Useful gene and plasmid DNA mixed and inserted into plasmid ; h bonds form between bases in sticky ends of plasmid
DNA Ligase used to join plasmid DNA and the useful gene together ; joins end nucleotides to end nucleotides of the plasmid
31
Plasmid description after?
Recombinant ; altered and has DNA from more than 1 source
32
Recombinant plasmid
Placed in bacteria and acts a vector in carrying that gene in the bacterial cell
33
Genetic engineering of plants?
Plant cells do not have plasmids ; bacteria are commonly used to create GM plants
34
How is plant cell gm different?
Recombinant ti plasmid created and is then inserted into a bacteria (tumefaciens) to create a transgenic bacterial cell ; the bacteria infects the plant cells when grown together and thus carries the useful gene into the plant genome (able to now produce the protein coded for by the gene)
35
Gm plants?
Significant yield of food crops - feed the increasing human population (pest/disease/herbicide resistance)
36
Benefits and risk of using Genetic engineering?
GM bacteria can produce hormone insulin which is used to treat diabetes
Can grow clotting factors for inherited diseases
Few side effects because protein from bacteria are human proteins
Long term consequences of GMO are unknown - a lot of scepticism
More medicine to be produced
37
GMO positive?
Vaccines - helps provide safer and cheaper vaccines for deadly diseases
38
Gene therapy negatives?
If not accurate then can cause cancer ; gene is inserted too close to a cancer causing gene
39
Risk of stem cell treatment?
Cancer developing
Rejection by the immune system because transplanted cells are foreign
40
Use of embryonic stem cells?
Controversial
Treating diabetes by replacing insulin secreting cells
Replacing neurones
Etc
41
Induced pluripotent stem cells?
No rejection
Less controversial than embryonic stem cells
Testing it on cell cultures before being used in a patient
42
Totipotent vs pluripotent?
Totipotent can differentiate to become the placenta but pluripotent cannot
43
Domesticated animals!
Animals that humans have tamed
44
Selective breeding?
Choose animals with desirable outcomes and use them for breeding - offspring also shows these characteristics
45
Selective breeding?
Animals with desirable characteristics are identified and bred - happens in a cycle over and over ; desirable characteristic starts to increase in the population
46
Disadvantages of selective breeding?
Reduces gene pool/variation ; result of inbreeding which increases likelihood of genetic conditions occurring
47
Why does inbreeding cause genetic diseases?
Alleles are often recessive ; increased chance of animals being homozygous recessive and thus de looong the condition
48
Other concerns?
Ethically speaking whether welfare of animals is affected - characteristic may not be desirable for the animal rather than humans
49
Inbreeding?
Reduces ability to cope with environmental stresses/adapt to new diseases etc
50
Species?
Fertile offspring
51
Population
All of the organisms of one species found in an area
52
Natural selection
Mutations have caused genetic variation in populations ; individuals will have different characteristics
53
Selective advantage?
Organisms with the advantageous alleles are better suited to their environment ; survival of the fittest - over many generations thus becomes more common
54
What else can cause variation?
Environment can alter the phenotype
55
Functional enzyme in stomach
Optimum ph = 2
56
Functional enzyme in small intestine
Optimum ph = 8
57
Carbohydrase?
Insoluble carbohydrates to soluble glucose
58
Lipid breakdown
3 fatty acids + 1 glycerol
59
Digestive enzymes
Extracellular
60
Inside cells
Intracellular (respiration/photosynthesis)
61
Energy for respiration used for?
Protein synthesis
Active transport
Cell division
Muscle contraction
62
Prokaryote aerobic respiration
In cytoplasm
63
During exercise?
May break down glycogen stores into glucose for respiration
64
Anaerobic respiration
Cytoplasm
65
Neurone
Nerves are made of bundles of the axons of neurones
66
CNS
Made up of the brain and spinal cord (nerves running through the vertebrae) ; nerves from receptors in the sense organs bring impulses to the spinal cord which sends them to the brain for processing (sends back an impulse via spinal cord to nerves)
67
Spine?
CNS CONTAINS SPINAL CORD NOT SPINE
68
Where are receptors found?
In sense organs (not CNS)
69
Neurone?
Nerve cell - transmit electrical impulses (single nucleus and extensions of cytoplasm allow electrical impulses to travel through them)
70
Sensory neurones
Connect receptors (detect stimuli) with CNS
71
Relay neurones
Connect sensory to motor neurones? And allow communication to and from brain
72
Motor neurone?
Connect central nervous system to efffectors - produce a response (muscles and glands)
73
Sensory neuron
Cell body in middle
74
Motor
Cell body at the end
75
Relay
Thin axon
76
Axon
Electrical impulse travels down
77
Myelin sheath
Protects the axon and makes impulse travel faster - dendrites allow connection to other neurones
78
Synapse
Small gap between two neurones ; allow neurones to transmit electrical impulses to each other - allow many neurones to connect with each other at once (made between dendrites)
79
How do impulses cross synapse?
Causes chemical to be released - neurotransmitter diffuses from axon to neurone on other side ; binds to receptor which allows the impulse to be regenerated - travels down axon of other neurones etc
80
Reflex arc
Protect the body from harm - bypass the brain
81
Reflex arc chain of events
Stimulus -> sensory neurone -> relay neurone -> spinal cord -> motor neurone -> effector
82
Bronchi and bronchioles
Both contain cartilage to ensure the airway remains open
83
Air entering the body
Contains more oxygen
Less CO2
Less water vapour
Contains pollen, dust, viruses
84
Normal exhalation
Passive (when active muscles on abdominal wall will also contract)
85
Inhale
Intercostal muscle contract and pull up and out
Diaphragm flattens (contracts)
86
Where is co2 transported
Blood plamsa
87
Increase in heart rate?
Make blood flow faster - steeper concentrations gradients for oxygen and carbon dioxide
88
Heart
Coronary
89
Lungs
Pulmonary
90
Liver
Hepatic
91
Kidneys
Renal
92
Vein
Thin vessel with less muscle and elastic tissue
93
Arteries
Narrow lumen
94
PQRS complex
Electrical activity causing ventricles to contract
95
Factors affecting heart rate
Exercise and hormones
96
In a healthy person
RBCs most numerous and WBCs least numerous
97
Plasma contains
Glucose, urea and amino acids ; hormones, antibodies co2 etc (55% of blood)
98
Lymphocytes
Produce antibodies (proteins that target specific marker antigens) and some form memory cells in secondary immune response
99
Clotting
Platelets have no nucleus and stop blood loss/prevent microbes ; enzymes convert soluble fibrinogen into insoluble fibrin
100
ABO system?
Blood group system - gene for this system codes for a protein found on plasma membrane - immunoglobulin
101
How many alleles does ABO gene have?
3 - on,y two are present in any 1 person
102
A
I^A *2 (homozygous) OR I^A and I^O (with the A allele being dominant)
103
B
I^B (*2) - homozygous
I^B and I^O (B is dominant to O allele)
104
AB
I^A I^B (neither allele is dominant so they are co-dominant and so both are expressed)
105
O
Domination is homozygous recessive
106
Digestive system
Breakdown of insoluble molecules found in food into soluble products and absorption of these products of digestion
107
Digestive system food path
Mouth
Oesophagus
Stomach
Small intestine
Large intestine
108
Blood group phenotypes - donate to - receive from
A - A and AB - A and O
B - B and AB - B and O
AB - AB - Any blood group
O - Universal donor - O
109
Peristalsis
Wave of muscular contraction that move the bolus along
110
Mechanical
Teeth grinding/stomach churning
111
Chemical
Using bile/enzymes which are produced by specialised cells in glands and tissues in the gut lining
112
Enzymes and their conditions
Hydrochloric acid kills bacteria and provides correct pH for protease enzymes to digest protein
113
Bile and pancreatic juice
Contain HCO3- ions to neutralise the stomach acid and provide alkaline conditions needed by enzymes in small intestine
114
Function of bile?
Emulsify lipids to increase surface area for lipases to digest
115
Starch, proteins and lipid
Large insoluble molecules that cannot pass through the gut wall ; extracellular enzymes are secreted into the gut lumen to break down these molecules by hydrolysis
116
Fibre?
Cannot be digested and absorbed as enzyme not present
117
Glycerol and fatty acids
Small and soluble - pass through gut wall and into lymph system before entering blood
118
Active transport is used
When higher concentration of nutrients is present in the small intestine than in the blood
119
How are macromolecules made?
Condensation reactions
120
Not all good is digested
Fibre/indigestible components of food remain - these materials are then passed on to the large intestine - brown from bile pigments and into rectum
Expelled through EGESTION
121
Small intestine
Alkaline
122
In the liver
Deamination - excess amino acids are broken down
Nitrogen component converted to urea - can be toxic if too high so excreted by kidneys
Liver breaks down haemoglobin from RBCs - yellow pigment called bilirubin - excreted with bile into small intestine and expelled with faeces
123
Skin excretory substance?
Sweat - sodium chloride and traces of urea
124
Kidney
Remove urea - adjust ion content and adjust water content
125
Path of flow through kidney
Receives blood via renal artery from aorta - ultrafiltration to remove urea, excess water and sakes - filtered blood is returned to vena cava via renal vein
Mixture of substances removed from blood plasma (filtrate) is called urine - passes down ureter to bladder (where it is stored)
Sphincter muscle at the base controls release of urine through urethra
126
How does ultrafiltration work?
Through nephrons - each one has a glomerulus, renal capsule and renal tubule
127
Kidney composition?
Enters through renal artery - divides into arterioles and capillaries in the cortex
Capillary is knotted to form glomerulus (surrounded by bowman’s capsule)
Leads to convoluted tube - passes through medulla where it forms loop of Henle and returning to a distal convoluted tubule in cortex again
Tubule joins a collecting duct which passes down through the medulla into the pelvis
128
How does nephron work?
Pressure increases as blood enters glomerulus
Plasma proteins and blood cells are retained within capillary
Water dissolved ions glucose and urea are forced our via ultrafiltration
Filtrate collected in renal capsule and through renal tubule
As the filtrate passes along tubule - selective reabsorption takes place into capillaries surrounding the tubule
Glucose is reabsorbed by diffusion
Water reabsorbed via osmosis and salts to maintain correct concentration in the blood
Salts/urea/Uric acid not needed continue along tubule into medulla collecting duct
Duct delivers filtrate to the pelvis of the kidney where fluid passes into a ureter -> bladder
Urine is retained in the bladder by a sphincter muscle
Muscle wall of bladder contracts when sphincter relaxes to expel the urine through URETHRA
129
Kidney other functions
Remove chemicals which might poison enzymes in the cell
Control levels of salts/acids and water in the blood
130
On a hot day
More water lost in sweat - thus kidneys produce small volume of concentrated urine to conserve water (prevent dehydration)
Opposite for on a cold day - could become over-hydrated (could become swollen and burst via osmosis)
Regulation of how much water is excreted is determined by the hormone ADH
131
Blood leaving the kidney
Less water, fewer salts, less urea and less uric acid
Higher carbon dioxide concentration and a lower oxygen concentration than blood entering the kidney
132
Type 1 diabetes
Young people
Inability of pancreatic cells to secrete enough insulin
Can be inherited
Autoimmune disease - tired/thirsty/weight loss
Treatment through regular injections of insulin and carefully regulated diet
133
Type 2 diabetes
More common form of diabetes (older people) - can be inherited or a result of obesity - which could lead to insulin resistance
134
Osmoregulation
Brain signals to pituitary gland to increase or decrease amount of ADH
ADH binds to collecting ducts of nephrons and makes them more permeable
So high levels of ADH (on a hot day) means more water is reabsorbed and less urine excreted
135
Thermal regulation
Rise in temperature detected by thermoregulatory centre - responds by sending nerve impulses to the skin causing effectors to respond (sweat and vasodilation) -cooling
136
When it is too cold?
Shivering
Vasoconstriction - erection of hairs on surface of skin to create an insulating layer
137
Why is insulin injected rather than taken orally?
Protease enzymes would digest insulin if taken orally
138
Thyroid
Thyroxine - regulates metabolic rate
139
Pancreas - insulin and glucagon
140
Ovary
Oestrogen and progesterone
141
Pituitary gland
Stimulates other glands to release hormones
142
Release of thyroxine?
Controlled by thyroid stimulating hormone - which is released from the pituitary gland (keeps levels of thyroxine within a normal range)
143
What is level of thyroxine monitored by?
Hypothalamus
144
TSH?
Negative feedback cycle (released by pituitary gland)
145
Adrenaline?
Breakdown of glycogen to glucose
Increase breathing rate
Increase heart rate
Stimulates more blood flow to muscles
146
Ovulation
Release of eggs (ova) approximately every 28 days (around day 14 of menstrual cycle)
147
Testosterone
Male reproductive hormone and stimulates sperm production
148
FSH
Produced by pituitary and stimulates ovary to develop a follicle containing an egg and to produce oestrogen
149
Oestrogen
Stimulates uterus lining to thicken
150
LH
Pituitary gland - acts on target structures in ovary and stimulates the follicle to release the egg in the middle of the cycle
151
Progesterone
Secreted by empty follicle in the overt (corpus luteum) ; maintains lining of uterus so the fertilised egg may implant
152
Oestrogen and progesterone
Inhibit production of FSH and LH respectively
153
Decreased progesterone levels
Causes thickened uterus lining to break down and be discharged
154
Artificial administration of oestrogen and progesterone
Prevents ovulation by inhibiting FSH and LH production thus cannot ovulate
155
Progesterone
Stimulates production of thick cervical mucus so that sperm are unable to fertilise the egg
156
Cervix
Opening to uterus
157
Oral pill
Progesterone /combined (progesterone and oestrogen)
158
Problems with oral pill
Not 100% effective and side effects like nausea possible
No protection from STDs
Taken daily
159
Hormonal methods of contraception
Skin patch (contains same hormones as combined pill)
Injection (progesterone)
Implant (progesterone for up to 3 years)
Intrauterine devices - release progesterone and prevent implantation of embryo
160
Hormonal methods
Prevent ovulation
Do not decrease risk of STDs
161
Non hormonal methods
Barrier (condoms diaphragm (used with spermicide) spermicide)
Intrauterine decides/copper IUDs (prevent stern from surviving in uterus)
Surgical methods (permanent sterilisation or cutting oviducts/sperm ducts)
Natural - abstinence (100% effective)
162
Contraception
Effectiveness varies depending on individual
163
Viruses
Genetic material not in nucleus and they lack cytoplasm
164
HIV
Retrovirus (RNA in genetic material) and an enzyme called reverse transcriptase ; on,y found in retroviruses and catalysed conversion of RNA ago DNA
165
How can HIV be passed!
Bodily fluids (semen/vaginal fluid) or breast milk
166
How to prevent hiv transmission
Condom
Screening of blood
Bottle milk rather than breast milk
167
HIV+?
Virus parasites mean that the person has a reduced white blood cell count (weakened immune system) ; this leads them to have AIDS
No cure for HIV just drugs ti stop reverse transcriptase from functioning (anti-retro viral drugs)
168
Influenza
Spread by airborne droplets ; vaccines use an inactive/weakened virus to those with weakened immune system
169
Measles
Direct contact
MMR vaccine
170
TMV
Only transmitted via direct contact
Removing plants and crop rotation
171
Bacterial disease
Antibiotics ; antibiotic resistance is a big issue - can be prevented through vaccinations
172
Salmonella food positioning
Person ingests food with bacterium (reproduces in small intestines causing inflammation)
Prevention is by making sure frozen meat is throughly defrosted etc
Oral rehydration is needed to replace lost electrolytes
173
Protists
Eukaryotic organisms that are single called and have a nucleus - plasmodium (mosquito being the vector)
Tend to bite at dusk/dark so use mosquito nets or skin lotions with chemicals to repel mosquitos so they cannot be bitten - anti-malarial medication can also prevent infection by protist
174
Ways do interrupting mosquito life cycle
Fish as natural predators fo eat the larvae
Draining areas of stagnant water
175
Problem with insecticides?
Resistance to insecticides
176
Fungi
Displease through spores ; thus store them in dry conditions to prevent growth (anti fungal medication)
Athletes foot/aspergillosis
177
Vaccines
Contain a dead/inactive pathogen or a weakened virus - still has markers exclusive to that pathogen (antigens) - body responds with a primary immune response
Recognises non-self antigens
Lymphocytes reproduce -> also become memory cells for secondary immune response
Produce specific antibodies
Antibody antigen complex formed
Destroy the pathogen / phagocytosis through opsonins/agglutination
178
Can immunity be passed along to the next generation?
No UNLIKE resistance
179
To become a new medicine a series of trials are carried out
Preclinical - no tests on humans
Clinical - test on humans
180
General sequence of events
Testing on animals (safe for humans)
Few healthy people (safe/obvious side effects)
Few patients (make sure it works)
Double blind (no bias) placebo test on many patients
181
Double blind test
Neither researcher nor patient knows what they are testing for
182
Non-communicable diseases
Not infectious
Caused by interactions of many different factors
183
Common non-communicable diseases
Cardiovascular disease
Cancer
Liver disease
184
CVD
Coronary heart disease
Hypertension
Stroke
185
Coronary heart disease
Narrow blood vessels ; if these become blocked then heart will not receive enough for aerobic respiration - fat deposit called an atheroma or a blood clot usually
186
Hypertension
Raised blood pressure due to narrowing of an artery lumen or hardening of an artery so that it cannot expand when blood flow increases
187
Stroke
Part of the brain is deprived of oxygen-rich and glucose-rich blood ; narrowing and hardening of arteries supplying brain tissue leads to lack of blood
188
Factors that increase risk of CVD
Lifestyle choices (can be modified) - diet, exercise, obesity, smoking, alcohol
Non-modifiable factors - gender, heredity and increasing age
189
Life long medication with CVD
Statins - reduce cholesterol production which is a component of atheromas
Anti-coagulants - reduce the likelihood of blood clotting and thus blocking an artery
Anti-hypertensive drugs - cause blood vessels to relax so lumen diameter enlarges reducing blood pressure
190
Surgical procedure CVD
Mesh tube to increase the lumen diameter so no restriction in the flow ; mesh known as a stent
Bypass - re-route blood around a blockage in the coronary artery
191
Lifestyle change
Reduce smoking
More exercise
Balanced diet
192
Individual
Single living organism
193
Population
Group of organisms of one species living and interacting in the same area
194
Community
All of the populations of different species interacting with each other in an ecosystem
195
Habitat
Place where an organism lives
196
Ecosystem
Community of organisms and their biotic abiotic component interacting together with their environment
197
Abiotic factors
Oxygen/water availability, light intensity, ph, pollution, temperature, mineral ions
198
Changes to abiotic factors
Affects food webs
199
Biotic factors
Competition disease food supply predation
200
Competition
Intraspecific and interspecific
Food, territory, mate - competitive exclusion principle
201
Disease
Epidemics can reduce population size quickly (artificial too)
202
Food supply
If food in short supply then an increase in deaths or increase in emigration to a new source
203
Humans
Active predators - uncontrolled fishing to extinction
Predator prey cycles
204
Birth rate>death rate
Population will grow
205
Pollution
Can reduce oxygen available to a species or acid rain kills populations of trees
206
Climate change
Corals bleach and die ; solubility of oxygen decreases too
207
4 phases in population growth (sigmoid)
Lag phase - acclimatisation ; becomes mature and starts reproducing but very slowly
Log phase - no limiting factors - rapid breeding
Stationary phase - shortage of food or build up of toxic materials have an effect ; number of deaths = number of births
Death phase - lack of food, accumulation of toxins, disease, predators ; mortality rate higher than birth rate
208
What causes population increase?
Better control of diseases /lower infant mortality rates
209
Predation
Breeding rate may not be sufficient enough to replace those eaten
210
Mutualism
Both organisms benefit
211
Parasitism
One gains and the other is harmed
212
Amount of biomass decreases at each trophic level
Move/respire/homeostasis/egestion/not even eaten - less energy going up the chain
213
Photosynthesis
Uses up co2 to make carbon compounds - removes co2 from atmosphere - assimilated into bodes of consumers (through food chain)
214
Respiration
Releases carbon dioxide back into atmosphere - if mass deforestation takes place there is an imbalance (leading to global warming etc)
215
Decomposition
When organisms die they provide food for detritus feeders ; break down dead plants and animals through respiration to release energy (into atmosphere)
Organic molecules are then trapped and fossilised ; traps carbon for long time
Calcium carbonate shells trap carbon too
216
Combustion
co2 into atmosphere ; small branches and foliage are brunt releasing more co2 into atmosphere
217
Water cycle
Transpiration
Evaporation
Condensation
Precipitation
Osmosis
Excretion from animals
