Biology Paper 2: Topics 1 + 6-9 Flashcards
1
Q
What’s a prokaryote
A
OA single celled (prokaryotic cell) organism
2
Q
What’s the nucleus
A
Contains genetic material arranged in Chromosomes, controls activities of the cell
3
Q
What’s the cytoplasm
A
Contains enzymes which control chemical reactions that take place there
4
Q
What’s the cell membrane
A
Holds cell together, controls what enters and exits
5
Q
What’s the mitochondria
A
Where reactions for respiration happen
6
Q
What’s ribosomes
A
Involved in translation of genetic material in the synthesis of proteins
7
Q
What’s a rigid cell wall
A
Made of cellulose, supports and strengthens the cell
8
Q
What’s a large vacuole
A
Contains cell sap (weak solution of sugar and salts) maintains internal pressure of cell
9
Q
What is chromosomal DNA
A
Controls activities and replication, floats free in the cytoplasm
10
Q
What is plasmid dna
A
Small loops of extra dna, can be passed between bacteria, contains genes
11
Q
What are specialised cells
A
Cells with a structure adapted to its function
12
Q
What are the three units of measurement smaller than Millimeter
A
Millimetre, micrometer, Nanometer, picometre
13
Q
What are enzymes
A
Biological catalysts that speed up chemical reactions in the body without being changed
Enzymes have a high specificity for their substrate because the substrate must fit the active site
14
Q
What’s a substrate
A
The molecule changed in a reaction
15
Q
What’s an active site
A
Where the enzyme joins onto the substrate
16
Q
What happens when an enzyme denatures
A
Some bonds holding the enzyme together break, causing the shape of the enzymes active site to change, meaning substrate will no longer fit
17
Q
What’s the practical for investigating effect of pH on enzyme activity
A
Add amylase solution to heated water and pH buffer. Add starch solution to this, mix, use continuous sampling to time how quickly this solution breaks down the starch by putting it into wells of iodine in a spotting tile.
18
Q
What are the two equations for rate of reaction
A
Rate = 1000 / time Rate = change/time
19
Q
What do digestive enzymes do
A
Break down food into smaller, soluble molecules that can pass through walls of digestive system and absorbed into bloodstream
20
Q
What enzyme breaks down the following, and what into?
Carbohydrates, proteins, lipids, glucose
A
Carbohydrate >carbohydrase> simple sugars
Proteins >protease>amino acids
Lipids >lipase> glycerol + fatty acids
Chains of glucose molecules >glycogen synthase> glycogen
21
Q
What’s glycogen
A
Molecule used to store energy in animals
22
Q
What’s diffusion
A
Net movement of particles from area higher to lower concentration
Liquids and gases, only small molecules can diffuse through cell membranes
23
Q
What’s osmosis
A
Net movement of water molecules from region of higher water concentration to lower water concentration, across a partially permeable Membrane (small holes in)
24
Q
What’s active transport
A
Movement of particles across a membrane against a concentration gradient using energy transferred during respiration
25
Equation for percentage change in mass
Percentage change = ((final mass- initial mass) / initial mass ) x 100
26
What is photosynthesis
When photosynthetic organisms use energy from the sun to make glucose, which is used to make larger complex molecules which make up the organisms’ biomass (mass of a living material)
27
Give balanced formulaic and written equation for photosynthesis. What could affect this equation’s rate?
Carbon dioxide + water > glucose + oxygen
6CO2 + 6H2O > C6H12O6 + 6O2
Its an endothermic reaction. Rate affected by light intensity, concentration of CO2 and temperature
28
Describe experiment to investigate effect of light intensity on rate of photosynthesis
Algal balls in water and sodium hydrogen carbonate, which releases CO2 in solution. Algal balls in this, white light on flask. Gas syringe to measure oxygen released.
29
How does light intensity, CO2 and temperature affect rate of photosynthesis
They’re all limiting factors
Rate of photosynthesis directly proportional to light intensity till a certain point, light transfers the energy needed for photosynthesis
Increasing CO2 increases rate of photosynthesis
Temperature too low and enzymes too slow, too hot and they denature (around 45* in photosynthesis)
30
What’s the inverse square law for light intensity in regards to photosynthesis
Light intensity is directly proportional to 1/distance^2
31
What are xylem and phloem
The two types of transport vessel in plants
32
What do root hair cells do
Grown on surface of roots, stick out into soil,gives plants large surface area for absorbing mineral ions and water from soil. Absorb minerals by active transport, water by osmosis
33
What do phloem tubes do
Made of columns of elongated living cells, small pores in end walls to allow stuff to flow through
34
What’s translocation
Process of transporting food substances (sucrose) made in leaves to rest of plant for use or storage. This transport goes in both directions and requires energy from respiration
35
What do xylem tubes do
Dead cells joined end to end, end cells between them. Hole down the middle, strengthened with lignin (a material). Carry water and mineral ions from roots, to stem and leaves
36
What’s a Transpiration Stream
Movement of water from roots, through xylem and out of leaves. Caused by evaporation and diffusion of water from plants surface. The loss of water causes more water to be drawn up through xylem to replace it. More water being drawn from roots causes a constant transpiration stream of water and mineral ions being dissolved in through the plant
37
What’s a stomata
Tiny pore on surge of plant, usually on leaves. Allows CO2 and oxygen to diffuse in and out of leaf. Water escapes leaves through stomata by diffusion during transpiration
38
What are guard cells
Surround the stomata. When turgid, the stomata open. When flaccid, the stomata close.
39
What does turgid mean and what does flaccid mean
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Turgid = swollen with water
Flaccid = low on water, limp
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40
What environmental factors is transpiration rate affected by and how
Light intensity: bright light = greater transpiration rate (stomata close in the dark)
Temperature: warmer temp = faster transpiration (warm, water particles have more energy)
Air flow: better air flow around leaf = greater transpiration rate, as a good air flow means water vapour is swept away, so theres a low concentration of water, which means more is drawn up ti replace it
41
What’s a potometer? Describe how you’d set up an experiment to use it
Measures water uptake by plant, estimating transpiration rate
Set up plant with a capillary tube with a scale leading to a beaker of water underneath, and to the right of the plant (in water) is a reservoir of water with a tap, which is shut off during experiment
Start stopwatch, record distance moved by air bubble per unit time. Speed of air bubble movement gives estimate of transpiration rate
42
What are hormones
Chemicals released directly into the blood that affect particular cells in target organs. They control things in organs and cells that need constant adjustment
43
What is the endocrine system
The endocrine system is made up of endocrine glands. Endocrine glands are Where hormones are produced and secreted from.
44
What’s the pituitary gland produce
Many hormones which regulate body conditions. These hormones act on other glands
45
What’s the ovaries produce
Produce oestrogen, involved in the menstrual cycle
46
What’s the testes produce
Produce testosterone, controls puberty and sperm production
47
What’s the thyroid gland produce
Produces thyroxine, regulates things like rate of metabolism, heart rate and temperature
48
What’s the adrenal gland produce and how does it work
Adrenaline, leads to a fight or fight response by activating processes which increase supply of oxygen and glucose to cells. The adrenaline binds to receptors in heart/liver/brain
49
What’s the pancreas produce
Produces insulin, regulates blood glucose level
50
What’s the difference between neurones and hormones
Neurones Fast acting, acts for a short time on a precise area
Hormones are slower acting, act for a long time in a more general way
51
What’s a negative feedback system
Body detects levels of a substance are above or below normal, triggers a response to get them back to normal
52
What’s metabolic rate
Speed at which chemical reactions in body occur
53
Describe the negative feedback system for thyroxine
Blood thyroxine low > hypothalamus (structure in brain) is stimulated to release thyrotropin releasing hormone (TRH) which stimulates pituitary gland to release thyroid stimulating hormone (TSH)
TSH stimulates thyroid gland to release thyroxine > blood thyroxine level rises back to normal
Blood thyroxine levels higher than normal > release of TRH from hypothalamus inhibited > reduces production of TSH > blood thyroxine level falls
54
Describe the stages of the menstrual cycle
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Stage 1: endometrium breaks down, egg released
Stage 2 (Day 4-14): uterus lining repaired, becomes thick, spongey layer full of blood vessels, ready for fertilised egg to implant there
Stage 3 (Day 14): egg develops + released from ovary (ovulation)
Stage 4: lining maintained until day 28. If no egg fertilised and implanted in lining, it breaks down and cycle begins again
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55
What are the hormones menstrual cycle is controlled by
Follicle stimulating hormone: causes follicle (an egg+it’s surrounding cells) to mature in an ovary + stimulates oestrogen production
Oestrogen: released by ovaries, causes lining of uterus to thicken/grow. A high level stimulates an LH surge (rapid increase)
Luteinising hormone: released by pituitary gland. LH surge stimulates ovulation at day 14; follicle ruptures, egg released. Stimulates remains of follicle to develop into a corpus lutem, which secretes progesterone
Progesterone: released by corpus lutem after ovulation, maintains lining of uterus and inhibits release of FSH and LH
When level of progesterone falls + low oestrogen level, uterus lining breaks down. Low progesterone level allows FSH to increase, so cycle begins again. If fertilised egg implants in uterus, progesterone level remains high
56
Describe two ways to help an in fertile woman reproduce
Clamifine therapy: woman infertile because doesn’t ovulate regularly. Take clamifine drug, causes more Follicle stimulating hormone and luteinising hormone to be released, stimulates egg maturation and fertilisation
IVF (in vitro fertilisation) eggs collected from women’s ovaries, fertilised them in lab using mans sperm. These grow into embryos.
57
Describe how hormones can be used to prevent pregnancy
Oestrogen taken every day inhibits production of Follicle Stimulating Hormone, eventually egg development and production stop
Progesterone taken stimulates production of thick cervical mucus, prevents sperm getting through cervix (entrance to uterus) and reaching egg
Mini pill + contraception injection contain progesterone only
Combined pill + contraceptive patch contain progesterone and oestrogen
Barrier methods prevent contraception
58
What’s homeostasis
Process of maintaining a constant internal environment. Negative feedback systems help with this
59
How is type one diabetes caused, how can it be controlled
Pancreas produce little or no insulin
Insulin therapy: inject insulin into blood at mealtime
Limit food rich in simple carbohydrate, exercise regularly
60
What’s type 2 diabetes and what’s it caused by, how can you control it
Body cells don’t respond properly to insulin or pancreas don’t produce enough insulin
High BMI and large waist to hip ratio ca lead to diabetes
Controlled by eating healthy diet, taking regular exercise and medication
61
What’s urea
Waste product produced by animals from proteins
62
What’s an alveoli? How do they work?
An exchange surface found in the lungs of mammals, adapted for efficient exchange of oxygen and carbon dioxide
Blood arrive at alveoli high in CO2, low in O2. O2 diffuses out of air in alveoli into blood, Co2 diffuses into alveoli to be breathed out. Alveoli have moist lining for dissolving gases, good blood supply to maintain concentration gradients, very thin walls (minimises distance gas moves), large surface area
63
How does exchange of materials work in single celled organisms
Gases and dissolved substances diffuse directly across cell membrane (large surface area compared to volume, so enough substances can be exchanged across membrane to supply volume of the cell)
64
How does exchange of materials work in multicellular organisms
Smaller surface area compared to volume means exchange surfaces are needed for efficient diffusion. A mass transport system moves substances around the body
65
What do red blood cells do
Carry oxygen from lungs to all cells in the body. Have biconcave disc shape and large surface area to absorb oxygen. Contain haemoglobin, binds to oxygen to become oxyhemoglobin
66
What are phagocytes
White blood cells, engulf microorganisms in phagocytosis
67
What are lymphocytes
White blood cells, produce antibodies against microorganisms and antitoxins, which neutralise toxins produced by the microorganism
68
What are platelets
Small fragments of cells, help blood clot at a wound
69
What’s plasma
A liquid that carries everything around in the blood
70
What are arteries and how do they work
Arteries; carry blood away from the heart. Walls strong and thick to pump blood at high pressures. Walls thick compared to lumen, contain layers of muscle and elastic fibre.
71
What are capillaries and how do they work
Capillaries; involved in exchange of materials at the tissues. Supply food and oxygen, remove waste. Small, fit between cells, exchange substances with them. Walls permeable, substances can diffuse out and in. Walls 1 cell thick, increases rate of diffusion by decreasing distance.
72
What are veins and how do they work
Veins; carry the blood to the heart. Have large lumen, helps the blood flow despite the low pressure. Valves keep blood flowing in the right direction
73
What’s a lumen
A hole down the middle of a blood vessel
74
Describe the circulatory system of mammals
Double circulatory system; blood pumped around in 2 circuits. Heart pumps deoxygenated blood to lungs, takes in oxygen, returns it to the heart. In circuit 2, the heart pumps oxygenated blood to other organs, delivering oxygen to body cells. The deoxygenated blood returns to the heart.
75
Describe the structure of a mammalian heart
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4 chambers, 4 major blood vessels.
Left side (oxygenated blood): pulmonary vein > left atrium > left ventricle > (aorta) body
Right side (deoxygenated blood): vena cava > right atrium > right ventricle > (pulmonary artery) lungs
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Left ventricle has thicker wall because it pumps blood at high pressure. Valves prevent backflow of blood
76
What’s cardiac output? What’s the equation for it?
Total volume of blood pumped by ventricle every minute
Cardiac output (cm^3 min^-1) = heart rate (bpm) x stroke volume (cm^3)
77
How is blood glucose level controlled by pancreas
Blood glucose concentration too high > insulin added, removes glucose from blood by making liver turn glucose into glycogen
Blood glucose concentration too low >glucagon added, makes liver turn glycogen into glucose, so blood glucose increases
78
What is respiration
The process of transferring (releasing) energy from the breakdown of organic compounds (usually glucose). This energy is used for metabolic processes, contracting muscles and maintaining a steady body temperature
79
Whats aerobic respiration? Give the equation
The most efficient way to transfer energy from glucose
Glucose +oxygen > carbon dioxide + water
C6H12O6 + 6O2 > 6CO2 + 6H2O
80
What’s anaerobic respiration? Give the equation
Body cant supply enough oxygen to muscles. Transfers less energy, Glucose is partially broken down, lactic acid is produced. This is painful and leads to cramps
In animals: glucose > lactic acid
In plants: glucose > ethanol + CO2
81
What’s the practical for investigating respiration
Test tubes with soda lime granules (absorbs CO2) under cotton wool, woodlouce on top. Glass beeds with same mass as woodlouce instead of woodlouce in control tube. Have a manometer containing coloured fluid in both test tubes, with a calibrated scale in middle. This respirometer is in a water bath. Can calculate volume of oxygen taken in by woodlouce per minute, this is respiration
82
What is: individual, population, community, ecosystem
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Individual = a single organism
Population = all the organisms of one species in a habitat
Community = all organisms of different species living in a habitat
Ecosystem = a community of organisms along with all the abiotic (non living) conditions
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83
What’s a habitat, whats a species
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Habitat = a place where an organism lives
Species = a group of similar organisms, can reproduce to give genetically fertile offspring
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84
What’s interdependence
Interdependence = organisms depend on each other within a community
85
whats mutualism, whats parasites
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Mutualism = a beneficial relationship between two organisms
Parasites = take from host species, who don’t benefit
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86
Give three examples of abiotic factors, and three examples of biotic factors
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Abiotic = temperature, amount of water, light intensity, levels of pollutants
Biotic = competition with other species, predation
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87
How would you compare how common an organism is in two sample areas
Place /1m^2/ Quadrat (square frame enclosing a known area) on ground at random point in first sample area
Count all relative organisms in Quadrat
Repeat many times
Calculate mean number of organisms per Quadrat in 1st sample area
Mean = total number of organisms / number of Quadrats
Repeat above in second sample area. Compare two means
88
What’s equation for population size of organism in one sample area
Mean number of organisms per m^2 x total area of habitat
89
What’s the practical for studying distribution along a gradient using belt transects
Mark line in desired area of study. Collect data along line using Quadrats placed at regular intervals. Repeat several times, calculate mean. Plot graph to see if the changing abiotic factor is correlated with a change in distribution of relevant species
Abiotic factors changing across a habitat is called a gradient
Quadrats laid out on a line form a belt transect
90
What is biodiversity
The variety of living organisms in an ecosystem
91
What’s eutrophication
Excess nutrients in water
92
Describe the eutrophication process
Fertilisers add excess nitrates to water. They cause algae to grow quickly, blocking sunlight. Plants cant photosynthesise, so die. Microorganisms that feed on decomposing plants increase in number and use up oxygen in the water. Organisms needing oxygen for aerobic respiration die
93
How do fish farms decrease biodiversity
Food added to nets produces waste, causing eutrophication
Farms breeding sites for parasites
Predators attracted to nets, get trapped and die
Farmed fish escaping into wild is problematic for indigenous species
94
What’s reforestation
Land where a forest previously stood is replanted, restoring biodiversity of forests
95
What are conservation schemes
Protect at risk species, protecting biodiversity
96
What is an ecosystem
All organisms living in an area + the non living (abiotic) conditions
97
Describe the carbon cycle
CO2 in air goes to plants through photosynthesis
Eating passes carbon compounds in plants to animals
Plants and animals die and decompose or are turned into useful products by humans
Decomposing animals/plants broken down by microorganisms, decomposers release CO2 into air by respiring
Useful plant/animal products burnt, release CO2 into air through combustion
98
What is the concept of decomposition of materials
Materials are recycled through the biotic and abiotic components of ecosystems
Decomposition of materials ensures habitats are maintained for the organisms living there
99
Explain the water cycle
Energy from sun evaporates water, becomes water vapour
In Transpiration water evaporates from plants
Warm water vapour carried up, condenses to form clouds
Water falls from clouds as precipitation, provides fresh water
Water drains into sea, process restarts
100
What’s potable water
Suitable for drinking
101
What’s desalination
Produce potable water from salt water. Removes the salt (mineral ions)
102
Describe thermal desalination
Water begins in large enclosed vessel, evaporates. Steam rises to top of vessel, salt stays at bottom. Steam travels down pipe and condenses into pure water
103
Describe reverse osmosis
Net movement of water molecules from an area of high salt concentration to an area of low salt concentration
Salt water treated to remove solids, fed at high pressure into vessel containing partially permeable membrane
Pressure causes water to move in opposite direction to osmosis
Water forces through membrane, salts left behind.
104
Describe the nitrogen cycle
Needed for making proteins for growth
Nitrogen in air turned into mineral ions for plants to use. Plants absorb them from soil, used to make proteins. Proteins carried along food chains.
Decomposers break down proteins into decomposing plants/animals + urea in animal waste. This returns nitrogen to soil.
105
What’s nitrogen fixation
Process of turning N2 in air into usable nitrogen containing ions in soil
Nitrogen fixing bacteria in roots and soil
106
What do decomposers do in the nitrogen cycle
Decompose proteins + urea into ammonia. Ammonia forms ammonium ions in solution that plants can use
107
What do nitrifying bacteria do in the nitrogen cycle
Turn ammonia + decaying matter into nitrites, then into nitrates (different species of nitrifying bacteria, produce nitrites or nitrates)
108
What do nitrogen fixing bacteria do in the nitrogen cycle. Where is it found
Turn atmospheric N2 into ammonia, then into ammonium ions
Some nitrogen fixing bacteria live in soil, others in nodules on the roots of legume plants (eg peas, beans). The plants decompose, and the nitrogen stored in the nodules is retuned to the soil. Nitrogen ions leak our of the nodules during plant growth.
109
What do denitrifying bacteria do in the nitrogen cycle
Turn nitrates into N2 gas. Of no benefit to living organisms. Denitrifying Bacteria often found in waterlogged soils
110
How would farmers increase the amount of nitrates in soil
Crop rotation: different crops grow each year in a cycle, cycle usually includes a nitrogen fixing crop (legume)
Fertilisers: animal manure + compost, recycles nutrients by returning to soil through decomposition. Can use artificial fertilisers containing nitrates + other essential mineral ions
