Paper 2 Flashcards
1
Q
Describe the process of glycolysis.
[4 marks]
A
- Phosphorylation of glucose using ATP
- Oxidation of triose phosphate to pyruvate
- Net gain of 2 ATP
- NAD reduced
2
Q
Malonate inhibits a reaction in the Krebs cycle.
Explain why malonate would decrease the uptake of oxygen in a respiring cell.
[2 marks]
A
- Less reduced NAD
- Oxygen is the final electron acceptor
3
Q
Explain how a resting potential is maintained across the axon membrane in a neurone.
[3 marks]
A
- Higher concentration of potassium ions inside and higher concentration of sodium ions outside the neurone
- Membrane more permeable to potassium ions
- Sodium ions actively transported out and potassium ions in
4
Q
Explain why the speed of transmission is faster along a myelinated axon than along a non-myelinated axon.
[3 marks]
A
- Myelination provides electrical insulation
- In a saltatory conduction
- In non-myelinated axon depolarisation occurs along whole length of axon
5
Q
A scientist investigated the effect of inhibitors on neurones. She added a respiratory inhibitor to a neurone. The resting potential of the neurone changed from -70mV to 0mV.
Explain why.
[3 marks]
A
- Less ATP produced
- Less active transport
- Electrochemical gradient not maintained
6
Q
How does IAA affect growth curvature when too is removed from shoot and replaced on one side?
[3 marks]
A
- Tip produces IAA
- IAA diffuses into shoot
- More elongation of cells on one side
7
Q
How could you compare the IAA concentration in shoot tips from two different plant species.
In your answer you should refer to all the variable that should be controlled to produce a valid comparison.
[5 marks]
A
- Size of shoot
- Number of shoot tips
- Size of agar block
- Repeat several times and calculate a mean
- Compare degree of curvature on calibration curve
8
Q
In fruit flies, males have the sex chromosomes XY and the females have XX. In fruit flies, a gene for eye colour is carried on the X chromosome. The allele for red eyes, R, is dominant to the allele for white eyes, r.
Male fruit flies are more likely than female fruit flies to have white eyes.
Explain why.
[2 marks]
A
- Males have one allele
- Females need two recessive alleles
9
Q
Neonatal diabetes is a disease that affects newly born children. The disease is caused by a change in the amino acid sequence of insulin.
This change prevents insulin binding to its receptor. Explain why this change prevents insulin binding to its receptor.
[2 marks]
A
- Changes tertiary structure
- No longer complementary
10
Q
Myelodysplastic syndromes (MDS) are a group of malignant cancers. In MDS, the bone marrow does not produce healthy blood cells.
Haematopoietic stem cell transplantation (HSCT) is one treatment for MDS. In HSCT, the patient receives stem cells from the bone marrow of a person who does not have MDS. Before the treatment starts, the patients faulty bone marrow is destroyed.
For some patients, HSCT is an effective treatment for MDS.
Explain how.
[3 marks]
A
- Produces healthy blood cells
- No MDS blood cells
- Stem cells replicate
11
Q
MDS can develop from epidemic changes to tumour suppressor genes. In some patients, the drug AZA has reduced the effects of MDS. AZA is an inhibitor of DNA
methyltransderases. These enzymes add methyl groups to cytosine bases.
Suggest and explain how AZA can reduce the effects of MDS in some patients.
[3 marks]
A
- AZA reduces methylation of cytosine
- Tumour suppressor gene is expressed
- Prevents uncontrollable cell division
12
Q
Using your knowledge of the kidney, explain why glucose is found in the urine of a person with untreated diabetes.
[3 marks]
A
- High concentration of glucose in blood
- Not all of the glucose is reabsorbed at the proximal convoluted tubule
- Carrier proteins are saturated
13
Q
Describe and explain how the polymerase chain reaction (PCR) is used to amplify a DNA fragment.
[4 marks]
A
- Requires DNA fragment, DNA polymerase, DNA nucleotides and primers
- Heat to 95°C to break hydrogen bonds
- Reduce temperature to 55°C so primers bind to DNA
- Increase temperature to 72°C so DNA polymerase joins the nucleotides
14
Q
Describe a method that could be used to determine the mean percentage cover of algae on a coral reef.
[3 marks]
A
- Randomly place quadrats using random number generator
- Large sample of quadrats
- Divide by total percentage of number of quadrats
15
Q
Explain how succession results in a wide variety of fish living in coral reefs.
Do NOT describe the process of succession in your answer.
[2 marks]
A
- Increase in species diversity
- Provides more habitats
16
Q
Lake Malawi in East Africa has more species of fish than any other lake in the world.
Suggest and explain how this speciation may have occurred.
[4 marks]
A
- Variation due to mutations
- Allopatric speciation
- Different lakes have different selection pressures
- Reproductive isolation
17
Q
Loss of nutrients INTO Lake Malawi has resulted in a decrease in some fish populations.
Explain why.
[4 marks]
A
- Algal bloom blocks light
- Reduced photosynthesis so plants die
- Saprobionic microorganisms aerobically respire
- Less oxygen for fish to respire
18
Q
The mark-release-recapture method can be used to estimate the size of a fish population.
Explain how.
[4 marks]
A
- Collect sample, mark and release
- Ensure marking is non-toxic
- Allow time for fish to randomly distribute before collecting second sample
- Population = number in first sample x number in second sample divided by number of fish marked in second sample
19
Q
Suggest why the mark-release-recapture method can produce unreliable results in very large lakes.
[1 mark]
A
- Less chance of recapturing fish
20
Q
Succession occurs in natural ecosystems. Describe and explain how succession occurs.
[4 marks]
A
- Colonisation by pioneer species
- Pioneer species change the environment
- Environment becomes more suitable for new species
- Change in biodiversity
21
Q
Explain how a single base substitution causes a change in the structure of a polypeptide.
Do NOT include details of transcription & translation in your answer.
[3 marks]
A
- Change in primary structure
- Change in hydrogen bonds
- Alters tertiary structure
22
Q
Haematopoietic stem cell transplantation (HSCT) is a long-term treatment for sickle cell disease (SCD). In HSCT, the patient receives stem cells from the bone marrow of a person who does not have SCE. The donor is often the patients brother or sister. Before the treatment starts, the patients faulty bone marrow cells have to be destroyed.
Use this to explain how HSCT is an effective long-term treatment.
[3 marks]
A
- Produces healthy red blood cells
- No sickle cells produced
- Stem cells divide
23
Q
A student investigated the effects of indoleacetic acid (IAA) on the growth of oat seedlings.
Explain why the student removed the shoot tip from each seedling.
[2 marks]
A
- Tip produces IAA
- Affects concentration of IAA
24
Q
Explain why the student added glucose solution to each Petri dish.
[2 marks]
A
- For respiration
- To provide ATP for growth
25
Explain why the lids were kept on the Petri dishes.
[2 marks]
1. To reduce evaporation
2. Which would alter the concentration of IAA
26
Explain how a decrease in the concentration of calcium ions within muscle tissues could cause a decrease in the force of muscle contraction.
[3 marks]
1. Less tropmyosin moved from binding site
2. Fewer actinomyosin bridges formed
3. Myosin head does not move
27
In muscles, pyruvate is converted to lactate during prolonged exercise.
Explain why converting pyruvate to lactate allows the continued production of ATP by anaerobic respiration.
[2 marks]
1. Oxidises reduced NAD
2. So glycolysis continues
28
Explain how increasing a cell’s sensitivity to insulin will lower the blood glucose concentration.
[2 marks]
1. More insulin binds to receptors
2. Stimulates uptake of glucose by channel proteins
29
Explain how inhibiting adenylate cyclase May help to lower the blood glucose concentration.
[3 marks]
1. Less ATP is converted to cyclic AMP
2. Less kinase is activated
3. Less glyconeogenesis
30
Describe the role of glucagon gluconeogenesis.
Do NOT include details on the secondary messenger model of glucagon action.
[2 marks]
1. Attaches to receptors on target cell and stimulates enzymes
2. Amino acids are converted to glucose
31
A student obtained a solution of pigments from the leaves of a plant. Then the student used paper chromatography to separate the pigments.
Explain why the student marked the origin line using a pencil rather than ink.
[1 mark]
1. The ink and leaf pigments would mix
32
Describe the method the student used to separate the pigments after the solution of pigments had been applied to the origin.
[2 marks]
1. Level of solvent below origin line
2. Remove before solvent reaches top of paper
33
In photosynthesis, which chemicals are needed for the light-dependent reaction?
[1 mark]
1. NADP, ADP, Pi and water
34
Describe what happens during photoionisation in the light-dependent reaction.
[2 marks]
1. Chlorophyll absorbs light
2. Electrons are lost
35
What is a DNA probe?
[2 marks]
1. Short single strand of DNA
2. Bases complementary with DNA
36
DNA probes are used to detect specific base sequences of DNA.
Describe how the DNA is broken down into smaller fragments.
[2 marks]
1. Restriction endonuclease
2. Cuts DNA at recognition sequence
37
The DNA on the nylon membrane is treated to form single strands. Explain why.
[1 mark]
1. So DNA probe attaches
38
Describe how you could estimate the size of a population of sundews in a small marsh.
[5 marks]
1. Use a grid
2. Use a random number generator to obtain random coordinates
3. Count frequency in a quadrat
4. Collect a large sample and calculate a mean average
5. To calculate total number, mean number of plants per quadrat multiplied by number of quadrats
39
Suggest and explain how digesting insects helps the sundew to grow in soil with very low concentrations of some nutrients.
[2 marks]
1. Digestion of proteins
2. Provides amino acids
40
Damage to the myelin sheath of neurones can cause muscular paralysis.
Explain how.
[3 marks]
1. Depolarisation occurs across whole length of axon
2. Nerve impulses are slowed
3. At neuromuscular junction
41
Damage to the myelin sheath of neurones can cause heart rate irregularities.
Suggest and explain why.
[3 marks]
1. Slower impulses across parasympathetic pathway
2. Fewer impulses from cardiac centre
3. To SAN
42
Suggest and explain how the interaction of the radial muscles and circular muscles of the eye could cause the pupil to constrict (narrow).
[2 marks]
1. Circular muscles contract
2. Radial muscles relax
43
Explain how the fovea enables an eagle to see its prey in detail.
[3 marks]
1. High visual acuity
2. Each cone is connected to a single neurone
3. Cones send separate sets of impulses to the brain
44
The retina of an owl has a high density of rod cells.
Explain how this enables an owl to hunt its prey at night.
[3 marks]
1. High visual sensitivity
2. Several rods connected to a single neurone
3. Enough neurotransmitter to exceed threshold
45
Steroid hormones are hydrophobic.
Explain why steroid hormones can rapidly enter a cell by passing through its cell-surface membrane.
[2 marks]
1. Lipid soluble
2. Diffuse through phospholipid bilayer
46
In the cytoplasm, testosterone binds to a specific androgen receptor (AR).
Suggest and explain why testosterone binds to a specific AR.
[2 marks]
1. Has a specific tertiary structure
2. The structures are completely
47
The binding of testosterone to an AR changes the shape of the AR. This AR molecule now enters the nucleus and stimulates gene expression.
Suggest how the AR could stimulate gene expression:
[2 marks]
1. AR is a transcription factor
2. Stimulates RNA polymerase
48
A calorimeter can be used to determine the chemical energy store of biomass. A known mass of biomass is fully combusted in a calorimeter. The heat energy is released from this combustion increases the temperature of the water in the calorimeter. The increase in the temperature of a known volume of water is recorded.
Other than the thermometer explain how TWO features of the calorimeter would enable a valid measurement of the total heat energy released.
[2 marks]
1. Stirrer distributes heat energy
2. Air reduces conduction
3. Water has high specific heat capacity
49
In natural ecosystems, most of the light falling on producers is NOT used in photosynthesis.
Suggest TWO reasons why.
[2 marks]
1. Light is wrong wavelength
2. Light misses chlorophyll
50
The light absorbed by the chlorophyll is used in the light-dependent reaction.
Name TWO products of the light-dependent reaction that are required for the light-independent reaction
1. ATP
2. Reduced NADP
51
Explain the banding pattern of a relaxed single sarcomere
[3 marks]
1. I band only actin
2. H band only myosin
3. Overlapping region actin and myosin
52
Creatinine is produced in muscle tissues. Creatinine diffuses into the blood. The kidneys then excrete creatinine.
A calibration curve can be used to determine the concentration of creatinine in urine. One method of producing a calibration curve needs:
• creatinine solution of known concentration
• distilled water
• creatinine-detecting solution
• a colorimeter
Creatinine-detecting solution reacts with creatinine to produce an orange colour.
Describe how you could produce a calibration curve for creatinine.
[4 marks]
1. Use distilled water and creatinine solution to produce dilution series
2. Add creatinine detecting solution to each series
3. Use a constant volume of a solution
4. Record absorbance of solutions using a colorimeter
5. Plot concentration of creatinine solution against absorbance
53
Describe how you would determine the concentration of creatinine in a urine sample using your calibration curve.
[2 marks]
1. Use same volumes of solutions as used in producing calibration curve
2. Read off creatinine concentration against absorbance obtained
54
Describe the sequence of events involved in a transmission across a cholinergic synapse.
[5 marks]
1. Depolarisation of presynaptic membrane
2. Calcium channels open and calcium ions enter
3. Calcium ions cause synaptic vesicles to fuse with the presynaptic membrane and release acetylcholine
4. Acetylcholine diffuses across
5. Acetylcholine attaches to receptors on membrane
6. Sodium ions enter leading to depolarisation
55
Mutation is one cause of genetic variation in organisms.
Give TWO other causes of genetic variation.
1. Crossing over
2. Random fusion of gametes
56
A scientist wants to determine the dry mass of spinach plants. First, he heated each sample at 80°C for 2 hours.
Suggest what the scientist should do to ensure that he has removed all the water from the sample.
[2 marks]
1&2. Heat until sample remains the same mass
57
Alport syndrome (AS) is an inherited disorder that affects kidney glomeruli of both men and women. Affected individuals have proteinuria (high quantities of protein in their urine).
Suggest how AS could cause proteinuria.
[2 marks]
1. Damages basement membrane
2. Proteins can pass into the glomerular filtrate
58
AS results from a sex-linked mutation.
In a male with AS, where would the sex-linked mutation be located?
[1 mark]
1. The non-homologous section of a Y chromosome
59
A scientist produced transgenic zebra fish.
She obtained a gene from silverside fish. The gene codes for a growth hormone (GH).
She inserted copies of this GH gene into plasmids. She then micro injected these recombinant plasmids into fertilised egg cells of zebra fish.
Describe how enzymes could be used to insert the GH gene into a plasmid.
[2 marks]
1. Restriction endonuclease cuts plasmid
2. DNA ligase joins DNA and plasmid
60
Suggest and explain how delayed insertion of the GH gene could produce offspring of transgenic fish without the desired characteristic.
[2 marks]
1. Cell division has occurred
2. Cells producing gametes do not receive the gene
61
Black bears can hibernate for up to 7 months without food or water.
Suggest and explain how.
[3 marks]
1. Fat store used in respiration
2. Less energy is required due to low metabolism
3. Gluconeogenesis
4. Low surface area to volume ratio decreases heat loss
5. Long loop of Henle so less water lost
6. Water provided from respiration
7. Reduced urination
8. Less evaporation
62
During hibernation, the heart rate and metabolic rate of black bears decrease.
Use your knowledge of the nervous control of heart rate to describe how these are linked.
[4 marks]
1. Lower metabolism to less CO2 in blood
2. Detected by chemoreceptors
3. Chemoreceptors located in aorta
4. Fewer impulses to cardiac centre
5. Fewer impulses along sympathetic pathway
6. To SAN
63
Snowshoe hares within a population moult at different times.
Explain how this could ensure the survival of snowshoe hares populations in mountain habitats.
[4 marks]
1. Hares which moult earlier more likely to survive
2. Hares which moult earlier more likely to reproduce
3. Pass on advantageous allele
4. Frequency of allele increases in future populations
64
Climactic change has reduced the survival rate of snowshoe hares in mountain habitats.
Suggest and explain how.
[2 marks]
1. Less snow so less camouflage
2. More hares eaten by predators
65
A student used chromatography to separate the photosynthetic pigments in a chlorophyll solution. She had the following materials:
• chromatography paper
• a ruler and pencil
• suitable glassware
• a solvent (A)
• 2cm cubed of the chlorophyll solution
Describe how she could use them to separate the photosynthetic pigments by chromatography.
[4 marks]
1. Draw origin line on chromatography paper using a ruler and a pencil
2. Add chlorophyll solution to origin line
3. Add solvent A below origin
4. Remove before solvent reaches top
66
Using solvent A, the student separated 5 pigments. She then repeated the method using a different solvent (B). Using solvent B, she separated 6 pigments.
Explain the difference between these results.
[2 marks]
1&2. One pigment is soluble in solvent B but not in solvent A
67
Glutamate is a neurotransmitter involved in the transmission of nerve impulses from pain receptors to the brain. Ziconotide is a drug that can reduce severe, constant pain. Ziconotide blocks the calcium ion channels at some of the synapses which use glutamate.
The transmission of glutamate at synapses is similar to that of acetylcholine.
Explain how ziconotide reduces severe, constant pain.
[5 marks]
1. Fewer calcium ions enter synaptic knob
2. Fewer vesicles move to fuse with presynaptic membrane
3. Less glutamate diffuses across
4. Less glutamate attaches to receptors on the post synaptic membrane
5. Fewer sodium ions so fewer impulses sent to brain
68
Ziconotide is a polypeptide and acts on synapses in the spinal cord. Scientists investigated the effectiveness of ziconotide in reducing severe, constant pain. Ziconotide was injected into each patient's cerebrospinal fluid that bathes the brain and spinal cord. Patients recorded the intensity of their pain using a statistically valid scale.
Suggest two reasons why the patients had ziconotide injected into their cerebrospinal
fluid rather than taking a pill containing the drug.
[2 marks]
1. Quickly reaches spinal chord
2. Is broken down by enzymes
69
When the patients recorded the intensity of the pain, suggest TWO reasons why it was important to use a statistically valid scale.
[2 marks]
1. Pain is subjective
2. To ensure that differences in pain were statistically significant
70
What is associated with high sensitivity to light in the retina?
[1 mark]
1. Several photoreceptors connecting to one neurone and spatial summation
71
Describe and explain how THREE features of the cells in the proximal convoluted tubule allow the rapid re absorption of glucose into the blood.
[3 marks]
1. Microvilli provide a large surface area
2. Many channel proteins for facilitated diffusion
3. Many carrier proteins for active transport
4. Many channel proteins for co-transport
5. Many mitochondria produce ATP
6. Many ribosomes to produce carrier proteins
72
Antidiuretic hormone (ADH) binds to V receptors found in cell-surface membranes in two parts of a nephron.
Name the TWO parts of a nephron where V receptors are found.
[2 marks]
1. Collecting duct
2. Distal convoluted tubule
73
V receptors only bind with ADH.
Suggest and explain why.
1. Has a specific tertiary structure
2. They are complementary
74
A decrease in blood pressure stimulates the release of ADH.
Give the location of the receptors that detect a decrease in blood pressure and explain how the release of ADH will affect blood pressure.
[3 marks]
1. Aorta
2. ADH increases reabsorption of water
3. Increases volume of blood and pressure increases
75
In the following passage, the numbered spaces can be filled with biological terms.
An ecosystem supports a certain size of population of a species, called the (1) capacity. There are often numerous habitats within an ecosystem. Within a habitat, a species occupies a (2) governed by an adaptation to both (3) and biotic conditions. Populations of different species form a (4).
[2 marks]
(1). Carrying
(2). Niche
(3). Abiotic
(4). Community
76
Suggest TWO reasons for conserving rainforests.
[2 marks]
1. For biodiversity
2. Protect habitats
77
Give THREE reasons for the low efficiency of energy transfer from secondary consumers to tertiary consumers in an ecosystem.
[3 marks]
1. Heat loss from respiration
2. Food not digested
3. Excretion
78
The KRAS gene codes for a protein called K-Ras. The protein relays signals from outside a cell to a cell's nucleus, stimulating cell division. An alteration in the KRAS gene produces an oncogene which can cause a tumour to develop.
Suggest and explain how an alteration in the KRAS gene can cause a tumour to develop.
[3 marks]
1. Mutation in KRAS gene
2. Change in signalling protein
3. Results in rapid cell division
79
Short Tandem Repeats (STRs) are short sequences of DNA, usually 2 to 7 base pairs. STRs are repeated a number of times, one after another.
STRs are found throughout the whole genome.
The repeated sequences in STRs are common to all humans. Due to variation in the number of repeats, STRs are used in genetic fingerprinting.
Describe how STRs could be removed from a sample of DNA.
[2 marks]
1. Restriction endonucleases
2. Cut DNA at recognition site
80
Genetic fingerprinting using STRs requires amplification of the STRs using the polymerase chain reaction (PCR). The short base sequences either side of a specific STR are known.
Explain the importance of knowing these base sequences in PCR.
[2 marks]
1. For primers
2. To produce a complementary base sequence
81
During genetic fingerprinting, the different STRs are separated by gel electrophoresis.
Give TWO features of STRs which enable them to be separated by gel electrophoresis.
[2 marks]
1. Length/Mass
2. Negative charge
82
ATP is essential for muscle contraction.
Describe the roles of ATP in muscle contraction.
[2 marks]
1. To break actomyosin bridges
2. To move the myosin head
3. So actin filaments are moved
4. For the active transport of calcium ions
83
Describe and explain how taking creatine supplements and carbohydrate loading can improve performance of different types of muscle fibres during different types of exercise.
[5 marks]
1. Fast twitch fibres used during
short-term exercise
2. Slow twitch fibres used during
long-term exercise
3. Creatine used to form phosphocreatine
4. Phosphocreatine combines with ADP to form ATP
5. Glucose stored as glycogen
84
An increase in muscle activity causes an increase in heart rate.
Describe and explain how.
[4 marks]
1. Increase in CO2 detected by chemoreceptors
2. Sends more impulses to cardiac centre
3. More impulses along sympathetic pathway
4. To SAN
85
Exercise causes an increase in heart rate.
Describe the role of receptors and the nervous system in this process.
[4 marks]
1. Chemoreceptors detect raise in CO2
2. Send impulses to cardiac centre
3. More impulses to SAN
4. By parasympathetic system
86
Dengue is a serious disease that is caused by a virus. The virus is carried by one person to another by a mosquito. One method used to try and reduce transmission of this disease is the Sterile Insect Technique (SIT). This involves releasing large numbers of sterile males into the habitat. These males have been made infertile by radiation.
Explain how using the SIT could reduce transmission of dengue.
[2 marks]
1. Intraspecific competition
2. Reduces population
87
Describe how the mark-release-recapture method could be used to determine the population of the sterile males at the start of the investigation.
[3 marks]
1. Collect sample, mark and release
2. Leave time for mosquitoes to disperse before second sampling
3. Population= number in first sample x number in second sample divided by number of marked in second sample
88
Explain why an increase in shoot biomass can be taken as a measurement of net primary productivity.
[2 marks]
1. Represents dry mass/mass of carbon
2. Represents gross primary production minus respiratory loss
89
Each year, a few people with type 1 diabetes are given a pancreas transplant.
Pancreas transplants are not used to treat people with type 2 diabetes.
Give TWO reasons why pancreas transplants are not used for the treatment of type two diabetes.
[2 marks]
1. Type 2 produces insulin
2. Receptors less sensitive to insulin
3. Controlled by diet/exercise not a transplant
90
The pancreas produces the hormone insulin.
What are 3 actions of insulin?
[3 marks]
1. Activates enzymes involved in the conversion of glucose to glycogen
2. Controls the uptake of glucose by regulating the inclusion of channel proteins in the surface membrane of target cells
3. Attaches to receptors on the surfaces of target cells
91
What is meant by the term phenotype?
[2 marks]
1&2. Characteristics due to genotype and environment
92
Explain the role of reverse transcriptase in RT-PCR (reverse transcriptase-polymerase chain reaction)
[1 mark]
1. Create cDNA from mRNA
93
Explain the role of DNA polymerase in RT-PCR.
[1 mark]
1. Joins nucleotides to produce complementary strands of DNA
94
What is a gene pool?
[1 mark]
1. All the alleles in a population
95
Two species of palm tree diverged from eachother after their island was formed 6.5 million years ago. The flowering times of the 2 species are different.
Suggest how these two species of palm tree arose from sympatric speciation.
[5 marks]
1. Occurs in the same environment
2. Mutation causes different flowering times
3. Reproductive isolation
4. Change in frequency of alleles
5. Eventually different species cannot interbreed to produce fertile offspring
96
Describe how ultrafiltration occurs in a glomerulus.
[3 marks]
1. High hydrostatic pressure
2. Water and glucose pass out through pores in endothelium
3. Through basement membrane
97
Describe and explain how the excretion of ADH affects urine produced by the kidneys.
[4 marks]
1. Permeability of cells to water is increased
2. More water leaves distal tubule
3. Smaller volume of urine
4. Urine becomes more concentrated
