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96 Cards in this Set
- Front
- Back
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What are the major parts of an eukaryotic cell, and what are their functions?
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Cell Membrane - controls what goes in and out
Golgi apparatus - controls import and export of proteins Nucleus - brains of cell, stores DNA Rough Endoplasmic Reticulum - has ribosomes for formation of DNA Mitochondria - storehouse of energy |
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What are the two challenges imposed by fertilization?
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- avoiding cross-species hybrids
- maintaining a diploid state |
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How are cross-species hybrids avoided?
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- lock and key fit of ligand and receptor in sperm and egg cells
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What is the fast way of blocking polyspermy?
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- influx of Na ions changes electrical potential of oocyte plasma membrane
- prevents fusion of other sperm cells with plasma memrane - activated in 0.1 seconds - only lasts 1 minute |
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What is the slow way of blocking polyspermy?
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- signalling pathway in oocyte makes calcium concentration in cytoplasm
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What is triggered in the egg when sperm makes contact?
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a signal transduction cascade
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What are second messengers?
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- small molecules that link two transducer proteins in a signalling pathway
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What is the transducer in the egg cell cascade?
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Phospholipase C
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What are the second messengers n the egg cell cascade?
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Inositol triphosphate (IP3), and Ca 2+
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What are the features of a transduction pathway and where are they located?
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Outside Cell - Ligand 9proteins, small molecules)
At Membrane - Receptor (proteins) Cytoplasm - Transducer(s) (proteins, usually enzymes) and Second Messengers (small molecules, cofactors for enzymes) |
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What does the oocyte contribute to the zygote?
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Haploid nucleus
Cytoplasm Nutrients Ribosomes Mitochondria Stored mRNAs |
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What does the sperm cell contribute to the Zygot?
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Haploid nucleus
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What is in the grey crescent of frog eggs?
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Important cytoplasmic determinants
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Which side does the grey crescent correspond to in amphibians?
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The dorsal side of the embryo
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What are chromosomes?
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Continuous double helical stranded DNA, packaged with many proteins
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Genes are spread ______ along the length of the chromosomes.
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unevenly
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Is the coding region of a gene continuous?
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Not usually
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What is transcription and where in the cell does it occur?
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The making of a strand of mRNA, in the nucleus
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What is translation and where does it occur?
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Taking mRNA and making proteins through a ribosome, in the cytoplasm
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What is a blastomere?
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a cell resulting from cleavage of a fertilized egg
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What is a fate map for, and what are the three different levels they can be drawn at?
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- shows ultimate fate of embyotic cells
- used to predict a cell's fate levels: germ layers, tissues, cell types |
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What si the difference between cell fate and cell potential?
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potential can only be revealed experimentally
Cell potential is broader than cell fate Cell potential is lost as development proceeds |
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What is the order of development in an embryotic cell?
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Totipotency, pluripotency, determined, differentiated
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Define Totipotent
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cell can be anything
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Define pluripotent
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cell can be one of a range of things, but not everything
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What is mosaic development?
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when individual blastomeres are determined early (by the 8 -cell stage)
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What is regulative development?
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blastomeres remain undetermined during cleavage
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is genomic information lost during cell division?
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No, it is just turned off
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What are the three classes of protein-coding genes?
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Metabolic, Structural, Regultory
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What do metabolic protein-coding genes do?
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- encode enzymes that participate in basic cell metabolism
(expressed in all cells) - encode enzymes that have cell-specific functions (restricted to certain cell types) |
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What do structural protein-coding genes do?
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- encode structural proteins
(all cells, OR certain cell types) |
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What do regulatory protein-coding genes do?
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- encode proteins that regulate the expression of other genes
Expressed as transcription factors (act directly on gene regulatory sequences) or signalling factors (act indirectly on genes, often at cell surface) |
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What is the defining property of stem cells?
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Self-renewal
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What is a trophoblast?
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the membrane that forms the wall of the blastocyst in early development
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What is the cleavage stage?
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a period of rapid cell division without growth of the embryo
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What are cleavage patterns influenced by?
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amount of yolk, and orientation of mitotic spindles
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What is incomplete cleavage?
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Multiple nuclei in one cell around the outside of cell, yolk in middle
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What is a Drosophila?
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A fly
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Where are maternal effect genes expressed in Drosophila?
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nurse cell in female ovary
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What do maternal effect genes define?
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anterior and posterior end of embryo
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What are micoid and nanos? What do they do?
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RNA binding proteins, bind to specific sequences in mRNA and regulate translation
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What is gap gene expression?
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When genes are expressed with gaps in between the coding regions
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What is a blastodisc?
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A flattened disc of cells formed because of the egg yold in reptile and bird eggs
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What do cells in the organiser do?
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express and secrete proteins that influence the behaviour (cell movement) and identities (commitment) of nearby cells
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Autocrine?
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self-feedback loop
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paracrine?
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signal from one cell to neighbouring cell
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what does a morphogen do?
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reacts directly on a distant target cell, disrupts the relay mechanism f messaging through neighbouring cells
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What are morphogens?
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special signaling proteins that are involved in patterning embryos via gradient signalling
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What are the properties of morphogens?
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induce different cell fates at different concentrations
can act at a distance have a direct effect on target cell |
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What are the two major cell arrangements? Describe them.
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epithelial
- regular cell shape - tightly packed - many cell-cell contacts - simple or stacked sheets Mesenchymal - irregular shaped - loosely packed - few cell-cell contacts |
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What is somitogenesis?
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the segmentation of a vertebrate body
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What is a somite?
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blocks of cells made from condensed notochord
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What are the five processes that contribute to development? Describe them
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Determination
- fixing the fate of an embryotic cell Differentiation - process by which different cells arise Patterning - defining the orientation of the embryos and its tissues Morphogenesis - shaping of body and organs Growth - increase in size by cell division |
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animal vs vegetal pole?
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animal pole
- small cells that divide quickly - develops into embryo vegetal pole - large yolky cells that divide slowly - develop into placenta |
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what is a trophoplast?
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the membrane that forms the wall of the blastocyst in early development
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What influences cleavage patterns?
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- amount of yolk
- orientation of mitotic spindles |
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what is a homeobox?
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a sequence of genes found in a particular genus
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Conformers vs. regulators?
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Conformers allow external change to influence internal change. Regulators maintain constant internal environment
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Acclimatization vs Acclimation
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Acclimatization is a response in the wild due to nature
Acclimation is a response induced by lab settings |
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What is an endotherm? What are some examples?
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An endotherm generates heat from inside their own body through metabolic processes. Example: human
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What is an ectotherm? Example?
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An ectotherm needs heat from the environment. Example: reptiles
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What is a homeotherm?
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maintain a constant body temperature.
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What is a poikilotherm?
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An animal that has a fluctuating body temperature
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What is a heterotherm?
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an animal that regulates their body temp sometimes but not other times.
eg: hibernating mammals, small mammals and birds (shrew, hummingbird, bats), tuna and other related billfishes |
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Pros and Cons of Endothermy?
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Pros:
- sustain longer periods of activity - evolve highly efficient and specialized enzymes - can thrive on diverse environments Cons: - requires more energy - spend more time foraging, and less time on grown and reproduction - food and water intake = high metabolic rate > high resp. rate + high level of water loss |
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Pros and Cons of Ectothermy?
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Pros:
- spend little energy on thermoregulation - requires less food - more energy used for growth and reproduction - require less water - small in size Cons: - depends on environment for warmth - limited range of suitable environments - lower metabolic rate, less time spent in high intensity activity |
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What happens when endotherms cannot get enough energy to maintain body temp?
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- hibernate
- torpor - metabolic depression - death |
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Bergmann's rule?
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Mammals with wide distribution are larger in colder climates, making it so that they have more volume to SA
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Why are elephants so large if they live at the equator?
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Small SA to V helps prevent water loss
it takes more energy to heat a large mass of body body acts as a buffer |
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How to elephants cool down?
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When they get hot, they increase circulation to their ears
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How do polar bears keep warm?
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blubber - efficient at generating heat
white hairs reflect and transmit light - picks light up from sun hairs trap air as an insulator |
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Why do endotherms have a much higher metabolism than ectotherms?
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they have 5x the concentration of mitochondria in cells
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Aside from shivering, what can endotherms do to generate heat?
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- brown fat metabolism
- large concentration of mitochondria in brown fat - non-coupling (don't make ATP, just release heat) |
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Who has the most brown fat?
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young, lean women with normal blood sugar levels
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Where is the body's thermostat?
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In the hypothalamus
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metabolic depression vs. torpor vs. hibernation
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metabolic depression: drop a few degrees for a long period of time
torpor: drop 10-20 degrees nightly hibernation: drop 30 degrees for an extended amount of time. |
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Do bears hibernate? Why are there no large hibernators?
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reheating is too difficult
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What is freeze avoidance?
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- animals make "anti-freeze_ out of proteins and ion concentrated water
- make CRYOPROtECtANTS glycogens and sugars with lower freezing points |
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What is freeze tolerance?
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- promote ice crystal formation outside of the cell
- BUT water leaves cell because the concentration of water inside the cell is greater than that outside the cell |
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What hormones are an active part of kidney function, and what do they do?
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Aldosterone - from the adrenal gland, controls reabsorbtion of sodium into blood
Antidiuretic hormone (vassopression) - from the pituitary gland, controls absorbtion of water into the blood |
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Why does a higher salt intake lead to a higher blood pressure?
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too much salt leads to water retention, which leads to an increase of blood volume, which leads to a higher blood pressure
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How do diuretics work?
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they inhibit the production of antidiuretic hormone
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What are the two problems faced by the kangaroo rat, and how does it overcome them?
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- maintain ionic balance in hot & dry environment
- has a high metabolic rate - create higher concentration of urine - nocturnal - dry feces - no water loss from breathing |
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How can it make a higher concentration of urine?
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loop of Henle in a K rat is much longer
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What are xerophytes?
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plants that love dry environments
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How to xerophytes prevent water loss?
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- succulent form to store water
- heavy cuticle - regulate opening of stomata - deep tap roots |
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How does a cactus' stomata function?
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open at night, take in CO2
close in the day when it's dry and hot |
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What are halophytes? What problems do they face?
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plants that love salty environments
reduced water uptake due to saline conditions toxic effect of specific ions on enzyme function saline conditions inhibit growth |
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How to halophytes battle their environment?
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- use salt regulators such as ion pumps
- store salt in vacuoles |
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Define entrainment
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resting of circadian rhythm by environmental cues
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What is "free running?"
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Animal not bound to 24 hour cycle, clock runs on its natural cycle
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infradian
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a cycle that lasts less than a day
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ultradian
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a cycle that runs with a period of more than one day
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What part of the brain is responsible for maintaining the biological clock?
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suprachiasmic nucleus
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Why does it take so long to recover from jet-lag?
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glands in all parts of body to not recover together (synchronised)
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How does melatonin help with jet lag?
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works while you are sleeping
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