Bio Exam Flashcards

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1
Q

Types of evidence of Evolution

A

Fossils: Preserved remains (body fossils) provide direct evidence of ancestral forms and include bones, teeth, shells, leaves, etc. Traces provide indirect evidence of ancestral forms and include footprints, tooth marks, burrows, and feces (coprolite).

Transitional fossils: They establish the links between species by exhibiting traits common to both an ancestor and its predicted descendants

Selective breeding: Selective breeding provides evidence of evolution as targeted breeds can show significant variation in a (relatively) short period.

Homologous structures: Homologous structures are similar physical features in organisms that share a common ancestor, but the features serve completely different functions.

Speciation: The evolutionary process by which two related populations diverge into separate species is called speciation

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2
Q

Hierarchy of different taxa

A

Kingdom Katy
Phylum Perry
Class Comes
Order Over
Family For
Genus Grape
Species Soda

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3
Q

Homologous vs Analogous

A

Homologous structures: those that are similar in shape in different types of organisms. The structural similarities imply a common ancestry. The pentadactyl limb in vertebrates is an example of a homologous structure. Despite the obvious differences, all the organisms share the same bones. For example, the bones may vary in size and shape, but all vertebrates have five-fingered ‘hands’ at the end of each limb: This pattern is an indication of a common ancestor.

Analogous structures are features of different species that are similar in function but not necessarily in structure and which do not derive from a common ancestral feature (compared to homologous structures) and which evolved in response to a similar environmental challenge.

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4
Q

Variation leading to natural selection

A

Natural selection requires variation among members of a species in order to differentiate survival (variation needed for selection).

  • Mutations – Changing the genetic composition of gametes (germline mutation) leads to changed characteristics in offspring
  • Meiosis – Via either crossing over (prophase I) or independent assortment (metaphase I)

Crossing over: The exchange of genetic material occurs between non-sister chromatids at points called chiasmata. As a consequence of this recombination, all four chromatids that comprise the bivalent will be genetically different.

Independent assortment: When homologous chromosomes line up in metaphase I, their orientation towards the opposing poles is random. The orientation of each bivalent occurs independently, meaning different combinations of maternal/paternal chromosomes can be inherited when bivalents separate in anaphase I

  • Sexual reproduction – The combination of genetic material from two distinct sources creates new gene combinations in offspring
  • Inherited Variation – There is genetic variation within a population which can be inherited
  • Competition – There is a struggle for survival (species tend to produce more offspring than the environment can support)
  • Selection – Environmental pressures lead to differential reproduction within a population
  • Adaptations – Individuals with beneficial traits will be more likely to survive and pass these traits on to their offspring
  • Evolution – Over time, there is a change in allele frequency within the population gene pool
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5
Q

Structures, types and examples of carbohydrates, proteins and lipids

A

Carbohydrates:
Most abundant organic compound found in nature, composed primarily of C, H, and O atoms in a common ratio – (CH2O)n
Principally function as a source of energy (and as a short-term energy storage option)
Also important as a recognition molecule (e.g. glycoproteins) and as a structural component (part of DNA / RNA)

Lipids:
Non-polar, hydrophobic molecules which may come in a variety of forms (simple, complex or derived)
Lipids serve as a major component of cell membranes (phospholipids and cholesterol)
They may be utilized as a long-term energy storage molecule (fats and oils)

Proteins:
Makeover 50% of the dry weight of cells; are composed of C, H, O, and N atoms (some may include S)
Major regulatory molecules involved in catalysis (all enzymes are proteins)
May also function as structural molecules or play a role in cellular signaling (transduction pathways)

Carbohydrates:
Carbohydrates are composed of monomers called monosaccharides (‘single sugar unit’)
Monosaccharides are the building blocks of disaccharides (two sugar units) and polysaccharides (many sugar units)
Most monosaccharides form ring structures and can exist in different 3D configurations (stereoisomers)

Lipids:
Lipids exist as many different classes that vary in structure and hence do not contain a common recurring monomer
However several types of lipids (triglycerides, phospholipids, waxes) contain fatty acid chains as part of their overall structure
Fatty acids are long chains of hydrocarbons that may or may not contain double bonds (unsaturated vs saturated)

Proteins:
Proteins are composed of monomers called amino acids, which join together to form polypeptide chains
Each amino acid consists of a central carbon connected to an amine group (NH2) and an opposing carboxyl group (COOH)
A variable group (denoted ‘R’) gives different amino acids different properties (e.g. may be polar or nonpolar, etc.)

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6
Q

Enzyme activity (effect of different variables)

A

Temperature:
Low temperatures result in insufficient thermal energy for the activation of an enzyme-catalyzed reaction to proceed
Increasing the temperature will increase the speed and motion of both enzyme and substrate, resulting in higher enzyme activity
This is because a higher kinetic energy will result in more frequent collisions between the enzymes and substrates
At an optimal temperature (may vary for different enzymes), the rate of enzyme activity will be at its peak
Higher temperatures will cause enzyme stability to decrease, as the thermal energy disrupts the enzyme’s hydrogen bonds
This causes the enzyme (particularly the active site) to lose its shape, resulting in the loss of activity (denaturation)

pH:
Changing the pH will alter the charge of the enzyme, which in turn will alter protein solubility and overall shape
Changing the shape or charge of the active site will diminish its ability to bind the substrate, abrogating enzyme function
Enzymes have an optimal pH (which may differ between enzymes) and moving outside this range diminishes enzyme activity

Substrate Concentration:
Increasing substrate concentration will increase the activity of a corresponding enzyme
More substrates mean there is an increased chance of enzyme and substrate colliding and reacting within a given period
After a certain point, the rate of activity will cease to rise regardless of any further increases in substrate levels
This is because the environment is saturated with substrate and all enzymes are bound and reacting (Vmax)

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7
Q

Membrane transport

A

Active transport:
Sodium-potassium pump restore resting potential in the axon following nerve impulse
Reuptake of neurotransmitters to the presynaptic neuron following synaptic transmission.
Removal of Ca2+ from presynaptic neuron following synaptic transmission
Simple diffusion:
Diffusion of NT across synaptic cleft
Diffusion of K+ ions out of axon in resting potential
Facilitated diffusion:
Opening of voltage gated Na+ and K+ channels in action potential
Opening of voltage-gated Ca2+ channels at presynaptic terminal
Na+ channels activated at post-synaptic terminal to propagate AP
Vesicle transport:
Influx of Ca2+ activates vesicles of neurotransmitters
Exocytosis of NT from presynaptic neuron to synaptic cleft

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8
Q

Role of peptide hormones

A

Peptide hormones play a prominent role in controlling energy homeostasis and metabolism. They have been implicated in controlling appetite, the function of the gastrointestinal and cardiovascular systems, energy expenditure, and reproduction.

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9
Q

Causes of respiratory diseases

A
  • Radiation (X-rays)
  • Ageing (senescence)
  • Pollution (e.g. smog)
  • Environment (radon gas)
  • Diseases (e.g. COPD)
  • Genetics (family history)
  • Occupation (e.g. miners)
  • Asbestos (silicates)
  • Tobacco (smoking)
  • Smoke (secondhand)
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10
Q

Maintaining gas concentrations via the respiratory system

A

Because the gas exchange is a passive process, a ventilation system is needed to maintain a concentration gradient in alveoli
- Oxygen is consumed by cells during cellular respiration and carbon dioxide is produced as a waste product
- This means O2 is constantly being removed from the alveoli into the bloodstream (and CO2 is continually being released)
The lungs function as a ventilation system by continually cycling fresh air into the alveoli from the atmosphere
- This means O2 levels stay high in alveoli (and diffuse into the blood) and CO2 levels stay low (and diffuse from the blood)
- The lungs are also structured to have a very large surface area, so as to increase the overall rate of gas exchange

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11
Q

Process of in vitro fertilization

A

Down regulation: Drugs are used to halt the regular secretion of FSH and LH, which tops the secretion of estrogen and progesterone. Therefore, doctors can take control of the timing and quantity of egg production by the ovaries.
Superovulation: Involves using artificial doses of hormones to develop and collect multiple eggs from women. She is injected with large amounts of FSH to stimulate the development of many follicles. The follicles are treated by hCG, a hormone produced by a developing embryo. Egg is then collected prior to follicles rupturing.
Fertilization: Eggs are incubated in the presence of a sperm sample from male donor.
Implantation: Two weeks before implantation, she begins to take progesterone treatments to develop endometrium. Healthy embryos are selected and transferred into the female uterus. Multiple embryos are transferred for better luck of implantation. A pregnancy test is then taken 2 weeks after.

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12
Q

Role of the hormones insulin, glucagon, thyroxin and leptin

A

Thyroxin is secreted by the thyroid gland to regulate the metabolic rate and help control body temperature. It targets most body cells and effects the rate of protein synthesis, increases metabolic rate, increases heat production (e.g. increased respiration). Leptin is secreted by cells in adipose tissue and acts on the hypothalamus of the brain to inhibit appetite. It is produced by adipose cells (fat storage cells) and targets appetite control centre of the hypothalamus (in brain). It affects the increase in adipose tissue, resulting in the increase of leptin secretions into the blood, causing appetite inhibition and hence reduced food intake. If blood glucose is too high beta cells of pancreas produce something called insulin. Insulin stimulates uptake of glucose to cells, e.g: muscle. Insulin stimulates liver/fat cells to store glucose as glycogen, and leading to decrease in blood glucose. If blood glucose is too low, alpha cells of pancreas produce glucagon. Glucagon stimulates liver to break glycogen into glucose, and leads to increased blood sugar

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13
Q

Male and female reproductive organs

A

a. Uterus: provides protection, nutrients, and waste removal for developing fetus
b. Fallopian tubes: connects the ovary to the uterus, fertilization occurs here
c. Ovaries: eggs stored, develop, and mature. Produces estrogen and progesterone
d. Endometrium: develops each month in readiness for the implantation of a fertilized egg. Sheds during the menstrual cycle.
e. Cervix: Muscular opening to the uterus
f. Vagina: accepts penis during sexual intercourse and sperm is received.

a. Vas deferens: carries sperm to penis for ejaculation
b. Prostate gland: adds alkaline fluids that neutralize the vaginal acids
c. Urethra: delivers semen during ejaculation and semen for excretion
d. Penis: becomes erect to penetrate vagina during intercourse, delivers sperm to top of vagina
e. Seminal vesicle: adds nutrients like sugar for respiration and mucus to protect sperm
f. Epididymis: sperm is matured and stored here
g. Testis: produces sperm and testosterone
h. Scrotum: protects testes outside the body to maintain and lower optimum temp for sperm.

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14
Q

Blood clotting process

A

Wounds such as cuts to the skin causes opening through which pathogens can potentially enter the body. Blood clots at the site of a wound help prevent blood loss and the entry of pathogens. Platelets (small cell fragments) along with damaged tissue release clotting factors in response to a wound. Clotting factors cause a series of reactions which end with fibrin (a protein) fibres forming a mesh across the wound with. The fibrin fibres capture blood cells and platelets forming a clot. In the presence of fait the clot dries to form a scab with shields the healing tissue underneath.

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15
Q

Action potential graph (what is happening at each stage)

A
  1. Action potential is the reversal (depolarization) and restoration (repolarization) of the membrane potential as an impulse travels along it.
  2. The sodium-potassium pump (Na+/K+ pump) maintains the electrochemical gradient of the resting potential. Some K+ leaks out of the neuron (making the membrane potential negative, -70mv)
  3. In response to a stimulus (e.g. change in membrane potential) in an adjacent section of the neuron some voltage-gated Na+ channels open and sodium enters the neuron by diffusion.
  4. If a sufficient change in membrane potential is achieved (threshold potential) all voltage-gated Na+ channels open.
  5. The entry of Na+ causes the membrane potential to become positive (depolarization)
The depolarization of the membrane potential causes the voltage gated Na+ channels to close and the voltage gated K+ channels open.
  6. K+ diffuses out of the neuron rapidly and the membrane potential becomes negative again (repolarisation)
  7. Before the neuron is ready to propagate another impulse the distribution of Na+ (out) and K+ (in) needs to be reset by the Na+/K+ pump, returning the neuron to resting potential.
  8. This enforced rest (refractory period) ensures impulses can only travel in a single direction
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16
Q

Parts of a motor neuron

A

Dendrite: projection of cytoplasm that carries signals from outside the neuron toward the cell body
Axon: part of the neuron that carries impulses away from the cell body and toward other cells
Myelin Sheath: an insulating layer of fatty white tissue around an axon; allows impulses to travel quickly
Terminal knob: part of the neuron that attaches it to another cell
Synapse: the connection between the terminal knob of a neuron’s axon and a dendrite of an adjacent neuron
Nodes of Ranvier: areas between sections of my; nerve impulses jump from one node to another; increases the speed of transmission

17
Q

Pollination and seed dispersal

A

Pollination is the transfer of pollen from the anther to the stigma. Cross-pollination (transfer of pollen between different flowers) is preferred as it leads to greater variation in the next generation. Some flowering plants, e.g. grasses, rely on wind or water for pollination, but most use animals to transfer pollen.

Seed dispersal happens once the seed has developed in the ovule, it is ready for dispersal.
The difference between pollination and seed dispersal is that pollination is the transfer of the pollen from the anther to the stigma through water or wind or animals that transfer pollen, whereas seed dispersal happens only once the seed has developed in the ovule, hence ready for dispersal.

18
Q

Process of transpiration

A

Transpiration is the loss of water from leaves and stems of plants. Xylem vessels transport water through the plant (water has cohesive properties due to h-bonds). Water is heated in the mesophyll by sunlight and becomes vapour. This vapour transpires out of the stomata - pores in the leaf. Loss of water generates negative pressure and a transpiration pull on water molecules in the xylem. More water is drawn into the leaf. Cohesion between water molecules means that the transpiration pull has a knock-on effect through the plant. Higher rates of transpiration lead to a faster transpiration stream and higher rates of water uptake. Transpiration flow occurs through the xylem. The pits between xylem vessels allow sideways movement of water and ions. Upwards movement through xylem is generated by the transpiration pull: cohesion between water molecules allows water to be “sucked up.” Adhesion is the attraction between water molecules and the cellulose in the plant cell wall.
IN SUMMARY:
The loss of water from the top of xylem vessels due to evaporation lowers the pressure inside the vessel and pulls more water into the vessel due to cohesion. Adhesion attracts water molecules to the walls of xylem and vice versa. Therefore as the water moving upwards (similarly to cohesion) it pulls inward on the walls of the xylem vessels generating tension - try sucking n a straw when the bottom end is closed.
Transpiration flow is controlled by the rate of water loss through stomata. The opening of the stomata is caused by sunlight/high photosynthesis and reduced CO2 concentration. The closing of the stomata is caused by water shortage: the hormone abscisic acid is produced, forcing closure to prevent dehydration and darkness. When the stoma is closed the CO2 uptake is low, water loss is low, low pressure in cytoplasm, and the guard cells flaccid (as SZA would say keep it on the low). When the stoma is open the CO2 uptake is high, water loss is high, high pressure in cytoplasm, and the guard cells turgid (everything high pretty much). THE STOMA IS THE HOLE BTW. Transpiration is the inevitable consequence of gas exchange in the leaf.

19
Q

Phloem flow rates (how to record them)

A

Phloem transports water and solutes along hydrostatic pressure gradients.
- Relatively high concentration of sucrose and water in phloem sieve tubes.
- Water is incompressible, I.e. it occupies a fixed volume.
- The walls of the sieve tubes are rigid.
- These two factors cause a build-up of hydrostatic pressure at the source
- Water and the solutes (sucrose and amino acids) flow down the hydrostatic gradient to the sink where pressure is relatively low
- This is due to the active unloading of sucrose and hence loss of water by osmosis at the sink
You can use aphids to measure rates of phloem transport
1. A plant is grown in the lab and one leaf is exposed for a short time to CO2 containing the radioactive isotope 14C
2. The 14CO2 will be taken and incorporated into glucose by the process of photosynthesis. Glucose is converted into sucrose for translocation via the phloem
3. Aphids are encouraged to feed on the phloem in different locations of the stem at different times
4. The phloem is then analyzed for 14C content and the results can be used to calculate the rate at which substances move through the phloem
Measurement of phloem rates only became possible after the development of techniques that radioactively tagged compounds using 14C and the analyze its presence with electronic detectors or photographic film.

20
Q

Reproduction of flowering plants

A

The process of reproduction in angiosperms starts with pollination where pollen is carried from the anther of one flower to stigma of another. Then seed dispersal occurs once the seed has developed in the ovule, it is ready for dispersal. Lastly, fertilization occurs when the pollen tube grows down from the stigma to the ovary, through the style. Pollen is delivered to the ovum and fertilization occurs.

21
Q

Identify male and female gametes on flowers

A

The male gametes if the flower is the anther which contains the pollen and the female gametes if the plant is the ovary which contains the ovules. Ovules contain egg nuclei and develop into seeds when fertilized.

22
Q

Symmetry, segmentation, Digestive tract, and other features of Porifera (sponges)

A

none, none, no mouth or anus, porous, attached to rocks, and filter feeder

23
Q

Symmetry, segmentation, Digestive tract, and other features of Cnidaria (corals, jellyfish)

A

radial, none, mouth but no anus, stinging cells, and tentacles

24
Q

Symmetry, segmentation, Digestive tract, and other features of platyhelminth (flatworms)

A

bilateral, none, mouth but no anus, flattened body

25
Q

Symmetry, segmentation, Digestive tract, and other features of Annelida (earthworms, leeches)

A

bilateral, very segmented, mouth and anus, bristles often present

26
Q

Symmetry, segmentation, Digestive tract, and other features of Mollusca (oyster, snails, octopus)

A

bilateral, non-visible segmentation, mouth and anus, most have shell made of CaCO3

27
Q

Symmetry, segmentation, Digestive tract, and other features of Arthropoda (ant, scorpion, crab

A

bilateral, segmented, mouth and anus, exoskeleton, jointed appendages

28
Q

Symmetry, segmentation, Digestive tract, and other features of Chordata (fish, birds, mammals)

A

bilateral, segmented, mouth and anus, notochord, hollow dorsal nerve cord, some have pharyngeal slits