bio exam 2
Archaea
Also microscopic unicellular organisms Extremophiles Some aerobic, some anaerobic Share DNA and RNA organizational features with eukaryotes
Indicate how the Miller-Urey experiments provided evidence for the evolution of life on Earth.
Created conditions to simulate the conditions of early earth; atmosphere simulated by making electricity and methane, water vapor, ammonia, and hydrogen interact; boiling water created water vapor and a condenser formed water droplets to simulate the water cycle on early earth With this contraption, the scientists were able to consistently generate building blocks of complex molecules - amino acids, fatty acids, purines and pyrimidines, sugars, and phospholipids, which indicate that the building blocks for life could be developed in early earth conditions
Discuss the strategies that botanists are using to alleviate hunger and nutritional deficiencies.
Creating plants that are more drought, stress, and cold resistant - using genetic modification techniques to increase presence of genes that help plants survive drought and grow a more extensive root system/higher water-use efficiency Less dependent on fertilizer or water Resistant to pathogens More nutritious - identifying varieties of common crops that are more rich in nutrients (cassava - vitamin A; GMO crops with enriched nutrients
Roundworms
Occupy nearly every habitat on earth Some are parasites Move by alternating muscle contractions Open circulatory system, respiratory system, simple brains, and olfactory and touch systems
Explain how an action potential regenerates itself as it travels down an axon.
Reaches the same positive voltage at its peak at each point down the axon Regenerated by positive feedback at each point down the axon Localized concentration of positive charge inside the axon spreads away from the point of the action potential and to the other points of the negative charge further down the axon, depolarizing the membrane of the next segment of the axon to above the threshold potential
Characterize the wavelengths of light that you can (and cannot) detect, and the types of sensory cells that you use to detect them.
Rods and cones We cannot see infrared light Visual sensory cells Radio waves - can't detect with our ears
Flatworms
Lack circulatory and respiratory systems Nervous system has longitudinal ventral nerve cords that are connected by nerve fibers and allow coordinated movements Primitive brain - anterior concentration of nervous tissue
Sponges
Lack true tissues (nervous system or sensory cells) Body consists of cells imbedded in hydrogel Flagellated larvae are released and attach to substrates to allow movement Filter feeders - water-borne food particles flow into the sponge through pores and get trapped and ingested by specialized cells
Distinguish between a true nut, drupe and peanut.
True nut: dry fruit that has a hard shell covering a single seed (hazelnuts, chestnuts, acorns) Drupe: fleshy fruit with a hard seed inside (cherries, peaches, cashews, almonds, pecans) Peanut: species of legume in the pea family, seeds found in the plant's pods that ripen under the soil
Explain why tunicates and sponges are considered animals.
Tunicates: swimming larvae possess chordate features - they are motile and have a notochord (must be motile at some point in life to be an animal) Sponges: they are motile as larvae
Define turgor pressure and indicate its function importance to plants.
Turgor pressure: provides stability to cells, keeps them fully distended, helps them function normally; keep the stems and leaves erect and fully expanded; provides mechanical support to the non-woody tissues Leaf movements are controlled by change in turgor pressure in different parts of the plant
Explain how plants benefit from underground starch storage organs, oils, and the phytochemicals that humans extract from them for medicine, spices and perfumes.
Underground starch storage organs: during dry seasons/winters, plants conserve waters by allowing the aboveground portion of the plant to die and when conditions improve, they use the energy stored in the underground starch organs to fuel the regrowth of the aboveground structures Oils: attract pollinators, deter herbivores, prevent attack by fungi Phytochemicals: (underground organs) prevent attacks from herbivores, mold, bacteria; (aboveground organs - spices (seeds and leaves)) prevent attack by herbivores, mold, bacteria
Amphibians
thin moist skin that is a major site of gas exchange; eggs laid in water; may be aquatic, amphibious, or terrestrial; largely dependent on aquatic environments
Describe the fate of the 8 cells in the micropyle.
2 become the polar nuclei which becomes the endosperm (mother cell) 3 become the antipodal cells which disintegrate 3 others become the egg apparatus - 2 are synergids and one becomes the egg cell that is fertilized
Discuss the evidence that life initially evolved ~ 3.5 billion years ago.
2 main carbon isotopes: carbon-12 (99%) and carbon-13 (1%); bacteria take up c-12 and increase the ratio, so a high c-12 to c-13 ratio in sedimentary rocks is a sign of life, as it is assumed to be caused by the bacteria taking it up - 3.5 billion year old formation in Greenland has sediments enriched with c-12 Potential stromatolite fossils - stromatolites form when biofilms made of microorganisms (such as cyanobacteria, which are photosynthetic prokaryotes) trap sediments; presumed stromatolite fossils dating to 3.4 billion years old found in Australia, signaling that life could have evolved about 3.5 bya
Know the molar equation for photosynthesis.
6CO2 + 6H2O + sunlight → C6H12O6 (glucose) + 6O2
Explain how sucrose is loaded into phloem cells.
ATP is used to pump H+ against its gradient and out of the cell, a symport moves H+ back into the cell along with the sucrose molecules because of the low H+ concentration inside of the cell, loading the phloem cells with sucrose
Know the timing of key events in the evolution of life.
About 4bya, volcanic activity released large amounts of water into the atmosphere which formed the oceans Earliest cellular life at about 3.4 - 4.1 bya Organisms were first able to photosynthesize sunlight and produce oxygen about 2.5 - 3 bya, after which oxygen increased rapidly in the atmosphere; 1.7 bya - unicellular eukaryotes; 1.2 bya multicellular eukaryotes; 700 million years ago - animals, fungi, plants
Distinguish afferent neurons, efferent neurons and interneurons.
Afferent: bring information to the central nervous system Efferent: bring responses away from the central nervous system to varying parts of the body Interneurons: conveys information from one neuron to another
Contrast the life history of annual, biennial and perennial plants.
Annual: growth and reproduction completed in one growing season; mainly primary growth Biennial: roots, stems, leaves develop in the first season; reproduction occurs in the second season, followed by death; limited secondary growth in some species Perennial: growth and reproduction occur year after year; many species have secondary growth
Explain how the apoplastic and symplastic pathways transport water and minerals through the roots.
Apoplastic: water moves through nonliving regions, does not enter the cells, passes through one layer of living cells once it reaches the endodermis Symplastic: water passes into and through living cells, is taken up by root hairs and diffuses through the cytoplasm and passes from one living cell to the next
Outline the four steps (proposed by Oparin and Haldane) to explain the origin of the "protobiont."
Assemble building blocks for complex polymers (done by Miller and Urey) Polymerize the building blocks; assembly of larger molecules may have been assisted by substrates like clay which can act as a catalyst for self-assembly (strands of RNA and peptides have been produced this way in a laboratory) Assemble membranes: phospholipids self-assemble into bilayered microspheres which have properties of biological membranes (selective permeability and ability to anchor to protein molecules) - permitting complex organic molecules to concentrate in an exclusive environment Develop self-replicating molecules in protobionts; RNA may have been the first genetic molecule and could replicate itself without the help of additional enzymes; once packaged with their polypeptide products within a membrane, there would have been exclusive interactions and protobionts could have evolved as units and created proteins
Describe the composition of the "primordial soup" and explain what conditions permitted organic molecules to build up to high concentrations.
Atmosphere: methane, ammonia, water vapor, hydrogen Energy from UV radiation, lightning, and volcanic activity could have allowed organic molecules to form and accumulate in oceans
Describe how the acid-growth hypothesis helps explain how auxin causes the bending response of coleoptiles.
Auxin causes the cells on the shaded side to elongate and the side closest to the light source to bend toward the light Auxin triggers the pumping of H+ into the cell wall; expansin activates and breaks the cross bridges between the cellulose microfibrils; cellulose microfibrils loosen (turgor increases throughout the process) Cells expand and elongate, causing the seedling to bend to one side
Segmented worms (includes earthworms and leeches)
Body wall muscles divided into similar, repeating segments Complete digestive system (mouth and anus), closed circulatory system, no respiratory system - gasses diffuse through the skin Simple brain in the head and clusters of neurons (ganglia) in every segment Sensory organs can detect chemicals, moisture, light, touch
Explain why the three common myths about the brain are wrong.
Brains most important job is thinking: the brain's most important job is to run the physiological systems without any conscious thought; monitoring and controlling internal status Human's use only 10% of their brain: humans use nearly 100% of the brain throughout the day to varying degrees Young people have learned how to multitask effectively: people are really switching back and forth between different tasks, higher failure rate
Cephalochordata
Contain organs and organ systems similar to modern fish, but more primitive
Know the parts of a flower.
Carpel (female reproductive organs): stigma receives the pollen, pollen grain travels from the stigma down the style and into the ovary which has smaller ovules within Stamen (male reproductive organs): filament produces the pollen grains and the anther presents them for pollinators to collect
Describe how secondary growth occurs in the stems of eudicots.
Cell division displaces the cambial cells (underneath the bark), moving them outward even as xylem increases the stem or root thickness
Animals
Cells lack cell walls Heterotrophic Motile at some time in their lives (KEY)
Define the Law of Mass Balance.
Contents in any system/a part of any system is determined by the inputs and outputs of that system or part of the system Existing body load + intake or metabolic production - excretion or metabolic removal Homeostatic mechanisms help maintain the balance; must be an output to accompany an input in order for a system to maintain balance
Know the function of the key brain areas indicated on slide 18.
Cerebrum: controls movement, sensory processing, language and communication; seat of consciousness Corpus callosum: connects two hemispheres of the brain Hypothalamus: controls temperature, hunger, thirst, fatigue, sleep, circadian rhythm, kidney function Pituitary gland: master endocrine gland Pons and medulla oblongata: brain stem; regulates cardiac and respiratory function, consciousness, sleep cycle, integrates sensory input Cerebellum: equilibrium, posture, motor learning
Distinguish between climacteric and non-climacteric fruits.
Climacteric: can ripen after being picked Non-climacteric: only ripen on the plant, must be harvested and immediately transported to markets
Discuss the major differences between the nervous systems of Cnidarians, flatworms, insects, mollusks and vertebrates.
Cnidarian: nerve net; generate the same motor output no matter where a stimulus contacts their body; lack differentiated dendrites and axons but can generate action potentials; no brain, but concentrated area of neurons (around mouth) Flatworms: nerve cells are concentrated in the head for a primitive brain, connected to nerve cords that run the length of the body constituting a simple central nervous system; can localize the source of stimuli and generate movements toward or away from stimuli Arthropods: ventral/dorsal ganglia and ventral nerve cord Mollusks: lobed brain, ganglia associated with internal organs vertebrates: dorsal nerve cord, brain, sensory ganglia, brain; generate complex movements; can process a greater diversity of inputs and make more subtle and adaptive responses to the environment; have a higher cognitive capacity
Indicate how cohesion and adhesion facilitate transpiration.
Cohesion: molecules are attracted to each other and move as a continuous column up the vessel to the leaves as molecules pull other molecules with them Adhesion: water molecules adhere to the wall of the vessel and are able to travel up this way
Distinguish complete vs incomplete flowers, and monoecious vs dioecious plants.
Complete flower: contain both male and female reproductive organs Incomplete flower: only contains male or female reproductive system Monoecious plant: each plant produces flowers of both sexual types Dioecious plant: each plant is either male or female and produces male or female flowers
Distinguish the different types of flow-down gradients.
Concentration - based on the concentration of a chemical on either side of a membrane Electrical potential - based on the ionic charge of the inside or outside of an area Pressure Temperature
Describe the experiments that revealed the nature of the phototropic response of coleoptiles (oak seedlings) to light.
Darwin Seeking to discover the part of the oak seedling detected the light after noticing the seedlings curving toward the light source Manipulated seedlings: removed tip, tip covered with opaque cap, tip covered by transparent cap, site of curvature covered by opaque shield Concluded the tip of the seedling sensed the location of the light Boysen-Jensen Wanted to determine how the signal for phototropism (growth response triggered by exposure to a directional light source) is transmitted Cut the tips off and placed a block of gelatin (water permeable) in between the pieces of one seedling and a block of mica (water impermeable) in between the pieces of another Only the seedling with the water permeable barrier exhibited phototropism, indicating that a water permeable chemical was released and mediated the phototropic response Went Cut the tips from the seedlings Placed tips on agar blocks and allowed diffusible substances to move into the agar Growth stopped for the seedlings without the agar caps, but continued for those with the agar caps Experiment performed in the dark to prove that the chemical was sufficient to produce the bending response Concluded that the chemical was sufficient to produce bending and diffused down the seedling to cells right below the source of the chemical Extracted the chemical messenger for phototropism and called it auxin
Distinguish between diffusion, osmosis and tonicity
Diffusion Movement of a substance through an open system (water in a beaker, air) or across a membrane Substance moves down its concentration gradient (moves from high concentration to low) through a passive process (no ATP) Movement continues until system reaches dynamic equilibrium (most probable state) Osmosis Movement of water (ONLY WATER/SOLVENT) across a semipermeable membrane in response to its own concentration gradient Solute and water concentration are inversely related (high solute concentration = low water concentration) Water wants to achieve equilibrium on both sides of the membrane Tonicity Hypotonic: a lot of water in the solution, less water in the cell than outside, water enters the cell and it swells Hypertonic: not a lot of water in solution, more water in the cell than outside so the water leaves, cell shrinks Isotonic: equal level of water inside and outside the cell, cell does not change size
Discuss the adaptive significance of seed dispersal, and list the different ways that plants disperse their seeds.
Dispersing seeds reduces competition for light with the parent plant if nearby, permits colonization of new habitats, provides a nutrient-rich fertilizer for the seeds to germinate in Animals eating the fruit and excreting the seeds Attaching to other surfaces that come into contact with it Easily exploding seed structures Seeds with structures that allow the wind to carry them far
Describe the adaptive significance of fruits.
Encourage seed dispersal by packaging their seeds in tasty packages that animals will eat and disperse of Seeds are able to withstand the harsh environment of the digestive system Some are able to adhere to things that touch them in order to disperse themselves Some fling their seeds away from the body of the plant with only a light touch All of these adaptations allow for plants to encourage germination in other areas and continue to thrive
Discuss the lines of support for the endosymbiotic theory.
Endosymbiotic theory: to explain the origin of eukaryotic cells Mitochondria and chloroplasts are similar in size to bacteria Both organelles divide by binary fission and contain circular chromosomes that resemble bacterial chromosomes Both contain circular DNA molecules that closely resemble bacterial chromosomes Both genomes contain codes for ribosomes that resemble those found in bacteria rather than those found in eukaryotes Both surrounded by 2 or more membranes, the innermost of which has a chemical composition similar to that of bacterial plasma membrane Chloroplasts resemble cyanobacteria in their internal structure, including the presence of particular chlorophylls and the existence of thylakoids DNA sequence analyses indicate that chloroplast DNA most closely resemble extant cyanobacteria DNA
Describe the structure and function of the epidermis, and the different epidermal specializations.
Epidermis: covers the upper and lower surfaces of the leaf and other above and belowground structures Leaf epidermis: cells secrete a protective, waterproof layer called the cuticle that prevents water loss and and microbe attacks Leaf epidermis: trichomes secrete various substances that deters insects (i.e., THC from cannabis plants) Root epidermis: root hairs collect water and minerals from the soil and convey them to xylem cells Leaf epidermis: stomata allow products of photosynthesis to pass through the cuticle
Describe the structure of the leaf, and distinguish the three different classes of tissue.
Epidermis: covers upper and lower surfaces of the leaf, contains stomata Mesophyll: inside the lead, rich in chloroplasts Veins: contains vascular tissues (xylem and phloem), which transport materials in and out of the leaf Epidermis allows co2 to enter the plant, spongy mesophyll contains space to allow for gaseous exchange through stomata, palisade mesophyll is the main site of photosynthesis
Describe how commercial growers use ethylene and gibberellin to manipulate their fruits products in the supermarket.
Ethylene Multifunctional gaseous plant hormone Mediates seed germination, fruit ripening, death of flower and leaves Acts by binding to internal receptors (slow acting hormone) Commercial growers have massive controlled ripening facilities which provide control of temperature and ethylene concentration Gibberellin Promotes cell divisions, elongation of stems, development of seeds and fruits When sprayed on grapes, causes them to grow bigger When sprayed on flowers, stimulates growth
Explain how ethylene contributes to autumn foliage changes in deciduous trees.
Ethylene regulates leaf senescence (when they are in stress or changing seasons) Plants first degrade carbon and nitrogen and transport it to storage organs, including degrading the chlorophyll in leaves (which changes the color of leaves - underlying pigments are revealed) Ethylene stimulates production of enzymes that digest cell walls in the area of the leaf where it joins the stem, causing leaves to fall off
Describe the nature and function of a feed-forward (pre-emptive) response mechanism.
Feed-forward response mechanism: permit organisms to anticipate a change in internal conditions (homeostasis) so they can prepare and thus reduce the need for negative feedback (i.e., digestive system smelling/seeing/tasting food and preparing to digest and absorb it to avoid a huge change in internal conditions; flexing joints can cause the heart rate to increase; drinking water can quench thirst before water is actually absorbed into the body)
Bony fish
Fish that have skeletons made of bone and scaly skin; modifications in jaw that allow them to protrude the jaw and grab prey/draw it into their mouth
Distinguish among fish, amphibians, reptiles and mammals in terms of their dependence on water for reproduction.
Fish: require water for reproduction Amphibians: lay eggs in water, larvae develop in water - very dependent Reptiles: lay eggs on dry land, development also on dry land Mammals: not very dependent on water; most development occurs in the uterus or in an egg on land
List the different mechanisms that plants have evolved for dispersing their pollen.
Flowers have sugar-rich nectar to lure pollinators to feed, when feeding they will collect pollen on their bodies from the stamen Bright petals - insect pollinators can perceive UV wavelengths of light which can attract pollinators Some plants also use wind to disperse their pollen - stamen and carpels of some plants are designed to maximize the exposure to the wind
Describe the modular organization of the cerebral cortex.
Frontal lobe: coordinates information from other association areas, controls some behaviors Parietal lobe: sensory information from skin, musculoskeletal system, viscera and taste buds Occipital lobe: visual Temporal lobe: smell, hearing
Distinguish between a fruit and vegetable.
Fruit: seed bearing structure of a plant Vegetable: culinary term for the edible portion of a plant
Discuss the relationship between structure and function of organ systems.
Function of an organ is determined by its form Examining the structure of an organism can help explain how it works I.e., muscle cells are shaped in ways that make it easier for them to pull and contract
Distinguish functional and mechanistic explanations of biological phenomena.
Functional: why this biological phenomenon happens, what is the goal of it Mechanistic: how this phenomenon happens
Explain why Earth is referred to as a Goldilocks planet.
Gravitational forces are large enough to permit the formation of an atmosphere but not so large that they prevent the evolution of large body sizes and flight Average surface temperature between the freezing and boiling points of water
Describe what happens in gray versus white matter of the CNS.
Gray matter: has synapses, contains the circuits that do the thinking and integrating (processing) White matter: has myelinated axons that permit rapid communication within the brain and between the brain, spinal cord and body (communication)
Discuss the different ways that flowering plants reproduce asexually .
Growth of above and below ground structures help plants reproduce asexually Cloning - plants that share the same underground rhizome (ginger, quaking aspen) Potatoes can grow new potato plants by themselves Mother of thousands plant has many tiny plants that can all become an independent adult plant Grafting - aligning xylem and phloem of a plant with that of another plant to promote them to continue growing
Distinguish haploid and diploid cells.
Haploid cells: one set of chromosomes (1n), formed through meiosis which turns diploid cells into haploid cells, in plants occur in gametophyte tissues (sperm, eggs) Diploid cells: 2 sets of chromosomes (2n); formed by haploid cells fuse or diploid cells undergo mitosis, diploids occur in plants in sporophyte tissues (roots, stems, leaves) because the haploid cells have fused already and the plant is sexually mature
Describe the alternating generations in plants.
Haploid stage (sexual stage) - gametophyte (1 set of chromosomes); haploid stage describes the stage in which gametophytes produce gametes (sperm and egg) Diploid stage (asexual stage) - sporophyte (2 sets of chromosomes); diploid stage begins when the two gametes fuse and form a zygote, which develops into a multicellular embryo within a seed, and then a mature sporophyte through mitosis; meiosis in the flower of the mature sporophyte produce spores, which give rise to new gametophytes
Compare hormonal and neural signaling in terms of their speed of signaling and duration of impact.
Hormonal: slow speed of signaling; long duration of impact Neural: fast signaling (action potentials); short duration of impact
Explain the relationship between turgidity and hypotonicity in plant cells.
Hypotonicity means that the solution around the cell has more water than inside the cell, so water rushes into the cell down the concentration gradient and swells When there are hypotonic conditions and the plant cells are swollen, they are turgid and most healthy
Eukarya
Includes unicellular organisms like paramecium, slime molds, amoeba, red/brown/green algae, and all large multicellular organisms on earth Fungi Decomposers that break down and absorb biological molecules from dead organisms (i.e., leaf litter) Some form mutualistic symbioses with plants (birch, eucalyptus, oak, pine, rose families) Fungal roots (hyphae) grow into the root cells - fungus converts atmospheric nitrogen into food for plants, plant gives food to fungi
Explain why more plants evolved sexual methods of reproduction.
Increases genetic variation in the offspring by mixing alleles from both parents, meaning the offspring may have new and potentially adaptive traits Provides opportunities for DNA repair during meiosis Permits complementation - many harmful mutations are masked in the diploid state
Vertebrates (only chordates that have bones)
Internal skeleton that provides structural support for muscles and protection for nervous system and other organs - skeleton and muscles allow them to move fast through the environment
Be able to distinguish the different types of plants.
Land plants Vascular plants Seed plant Flowering plants
Indicate the sources of the oxygen that we breathe.
Land plants - 20-50% of total Aquatic plants - 50-80% of total Prochlorococcus (type of phytoplankton) is thought to be the most abundant photosynthetic organism and produce up to 20% of the earth's oxygen
Describe an action potential, and identify which voltage-gated ion channels are open/closed or activated/inactivated at each stage of an action potential.
Large, rapid, brief changes in membrane potential that occur when a membrane potential is depolarized to above a threshold potential Na+ activation gates open when threshold is reached, stopping depolarization Inactivation gates open after the influx of Na+, about a millisecond after the activation gates open to stop the inward flow of Na+ K+ channels open after the peak of the action potential and begin repolarization until the point of hyperpolarization, and then the membrane is at its resting value
Describe how the relationship between irradiance level and photosynthetic rate differs depending on whether leaves develop under sunny versus shady conditions.
Leaves grown in shady areas are thinner, have more surface area, and contain higher chlorophyll densities than those grown in sunny areas Sun-leaves have a higher rate of photosynthesis in high light conditions while shade-leaves are more efficient at harvesting sunlight under low light conditions
Explain the Panspermia hypothesis.
Life became trapped in debris ejected into space and survived the journey to Earth (to explain the presence of cyanobacteria on earth Supported by some meteors containing amino acids, an organic molecule group basic for life Also supported by extremophiles that thrive in harsh environments on earth; supposedly able to survive the harsh conditions of a meteor
Distinguish between local and systemic homeostatic controls.
Local: regulated by mechanisms within an organ (i.e., mechanisms within muscles can trigger increased blood flow to the muscle if they sense it is working intensely by adjusting things in the organ, not increasing heart rate) - between neighbors or itself Systemic: changes outside of an organ or organ system regulated by mechanisms in the brain, nervous and endocrine systems mostly in charge, regulation of several organs to be aimed at one common goal
Outline the experiments that revealed that it is the duration of uninterrupted darkness that determines when some (but not all) plants flower.
Long day and short day plants were exposed to a range of light conditions - when researchers interrupted a critical dark period with a pulse of red light, the plants' clocks were reset Flowering plants were exposed to a range of light conditions, and only the plant with an uninterrupted period of darkness for 16 hours flowered, while others with breaks of light did not flower Short day plants flower only when the night is longer than a critical length
Discuss how the stiffness of the basilar membrane (and hence sensitivity to sound frequencies) changes along its length.
Low frequency sounds cause vibrations at the most flexible region of the basilar membrane, while high pitched sounds cause vibration at the more stiff region of the membrane Closer to the eardrum the membrane is thicker The hairs of a specific region will bend and send signals to the brain that help them distinguish the frequency of the sound
Describe how fossil fuels were formed.
Made of decomposing plants and animals Coal - giant plants died in swamps millions of years ago, became buried under water and dirt over millions of years, heat and pressure turned the dead plants into coal over a long period of time Petroleum and natural gas - sea plants and animals died and were buried under the ocean floor, over time they were covered by layers of silt and sand, over millions of years they were buried deeper and the heat and pressure turned them into oil and gas
Know the different steps of double fertilization in the male and female reproductive structures.
Male: creation of pollen grains from microspores Microspores produce male gametophytes in the anthers Each anther holds diploid microsporocytes which undergo meiosis and produce 4 haploid microspores Inside each microspore wall, it divides by mitosis and produces a pollen grain (haploid male gametophyte) with 2 sperm cells and a tube cell which grows through the carpel to the ovary Mature male gametophyte has a pollen tube and sperm Female: eggs from megaspores Formation of the ovule in the ovary Ovule contains a megasporocyte which divides by meiosis to form 4 haploid megaspores, 3 of which disintegrate leaving 1 nuclei Mitosis occurs 3 (1 - 2 - 4 - 8) times to produce a single cell with 8 nuclei Cytoplasmic division creates a single large endosperm mother cell around 2, a wall forms around each of the other nuclei - 3 become antipodal cells which disintegrate, 3 others form a cluster where one may become fertilized and the other two synergids will assist in fertilization Embryo sac is created which contains 7 cells and 8 nuclei - female gametophyte Pollen grain lands on the stigma and germinates a pollen tube down toward the ovule which helps guide the pollen tube toward the ovule (pollen grain has 2 sperm) Pollen enters through the ovule's micropyle, two sperm are released into the dying synergid cell's cytoplasm One sperm nucleus fuses with the egg to form a diploid zygote, while the other sperm nucleus fuses with the endosperm mother cell (which has 2 nuclei already), forming a triploid nucleus called the endosperm which nourishes the embryo until its leaves form
These organisms differ greatly in terms of their internal anatomy and physiology. Be able to discuss these differences in terms of evolutionary adaptations to increasingly complex lifestyles and behaviors.
Mammals High metabolic rate, 4 chambered heart, high pressure circulatory system: high rate of oxygen delivery to tissues, maintain body temperature, high level of activity in many conditions Specializations of jaw, teeth, respiratory system: strong jaw muscles and 4 types of teeth allow them to feed efficiently on a diverse set of foods, ability to breath through the nose allows them to breathe and chew food at the same time Parental care: mammary glands produce an energy-rich milk to nourish their young, extended development in the uterus for placental mammals allows more carefully regulated conditions across development Complex brain: permits higher-level information processing and learning than other taxa Birds Hollow bones/lack of bony structures in wings, skull, etc., massive flight muscles, flight feathers, high metabolic rate: allow them to efficiently fly and provides energy for flight muscles Reptiles Waterproof skin with keratin and lipids, uric acid as waste product for nitrogen metabolism: prevents dehydration, causes them to lose less water during excretion
Describe the pathway that mediates the knee-jerk reflex, and its functional significance.
Mediated by circuits in the spinal cord I.e., when a muscle senses it is being stressed, receptors stimulate afferent nerves that transmit the impulses to the spinal cord and then efferent nerves from the spinal cord circuit respond These reflexes happen more quickly because the brain can be thinking about other things and the spinal cord will create this response
Describe the anatomy of the ear canal, middle ear, and cochlea.
Middle ear: has three bones that vibrate against each other and the oval window to intensify the initial vibration Cochlea: spiral tube that has chambers and the organ of corti - contains hair cells that detect the sound vibrations; vestibular duct, organ of corti, tympanic duct; the sound intensity is determined by the rate that the hairs are bent Ear canal: runs from outer ear to the eardrum Waves strike the membrane, middle ear bones vibrate at a certain frequency, vestibular duct creates waves that enter the duct Basilar membrane varies in responsiveness to low frequencies
Discuss the mechanisms by which mimosas and Venus fly traps sense contact by animals and generate "behavioral" responses.
Mimosa plants - when touched lightly, leaves on the same stems fold, when touched harder, leaves fold and stem droops Light touch reduces turgor pressure in the secondary pulvini (place where individual leaves are connected to the small stem) Hard touch reduces turgor pressure in the primary and secondary pulvini (place where stem meets the shoot and where stem meets leaves) Stimulation of the mechanoreceptor activates the folding mechanism - mediated by action potentials Action potentials spread through the phloem tubes to the pulvini and quickly cause them to lose turgor Venus fly traps - obtain nitrogen by attracting insects and trapping them within their leaves and then digesting them with an enzyme Trigger hairs in the leaves sense movement by insects and generate action potentials when they are bent When 2 of the hairs are stimulated within a 20s time period, the trap closes and traps the insect
Indicate how the nervous system represents different types of sensory input—i.e., modality, quality, location and intensity.
Modality: type of sensory cell that is stimulated (light, taste, etc.) Quality: within a modality, different categories of perception (different colors, tastes, smells) Location: defined by the source of the sensory information (location on the body, which nostril, eye, ear, etc.) Intensity: defined by the firing rate of action potentials
Differentiate between monocots and eudicots based on their distinctive morphological attributes.
Monocots (i.e., grasses, irises, cattail, palm trees, corn) one cotyledon in the seed usually three floral parts (or multiples of three) parallel leaf veins one pore in pollen grain Vascular bundles distributed all throughout ground tissue Branching fibrous root system Eudicots (i.e., maple and oak trees, etc.) Two cotyledons Four or five floral parts (or multiples of four or five) Net-like leaf vein arrangement Three pores in pollen grains Vascular bundles organized in a ring in ground tissue Main taproot with smaller lateral roots
Contrast the ionic composition of the intracellular and extracellular fluids of a neuron.
More potassium (K+) in the intracellular fluids, more sodium (Na+) in the extracellular fluids
Arthropods
More than half the animal species on earth Body encased in rigid exoskeleton Muscles attached to exoskeleton Open circulatory system Varying gas exchange mechanisms, don't breathe through mouth/nose Highly organized central nervous system
Explain how knowledge of structure offers insight into function.
Muscle example Neurons and nephrons
Explain the following quote: "For life to exist, it must overcome entropy."
Must overcome the natural dispersal and loss of energy, meaning it must consume energy from food sources and use the energy to maintain or create organization in their bodies
Distinguish between negative and positive feedback.
Negative feedback: change in a factor triggers a response to oppose the change and bring the factor back to normal by moving the factor in the opposite direction of the change Positive feedback: occurs to increase the change, encourages change in the same direction (continues changing the way that it initially changed) - not homeostatic
Distinguish the 11 organ systems
Nervous: can generate action potentials, monitors changes in internal and external environments, coordinates body activities (brain, spinal cord, peripheral nerves, sensory organs) Endocrine: regulates hormones (pituitary gland, hypothalamus, thyroid, pancreas, etc.) Respiratory: regulates breathing, converts oxygen into CO2 (lungs, diaphragm, trachea, etc.) Circulatory: regulates transportation of oxygen, nutrients, water, hormones around the body and carries away metabolic wastes, stabilizes internal temperature and pH (heart, blood vessels, blood) Digestive: digests food and controls the uptake of nutrients in the intestines by converting ingested food into molecules and ions that can be absorbed into the body, regulates water content (mouth, pharynx, esophagus, stomach, intestines, liver, pancreas, rectum, anus) Skeletal: supports and protects body parts, helps with movement, stores minerals (bones, tendons, ligaments, cartilage) Muscular: helps with movement, generates heat (muscles - skeletal, cardiac, smooth) Immune: prevents illness, attacks foreign bodies (lymph nodes, lymph ducts, spleen, thymus, bone marrow, white blood cells) - can contract Integumentary: covers external body surfaces and protects against injury and infection, regulates water content and body temperature (skin, sweat glands, hair, nails) Reproductive: creates gametes for reproduction, facilitates the growth of fetus, passes on genes to the next generation Excretory: excretes water, ions, metabolic wastes from body, helps regulate internal osmotic balance and pH, helps regulate blood pressure (kidneys, bladder, ureter, urethra)
Which groups of animals have no circulatory system, an open circulatory system or a closed circulatory system.
No circulatory system: sponges, cnidarians, flatworms Open circulatory system: mollusks, roundworms, arthropods Closed circulatory system: segmented worms, chordates
Chordates
Notochord that supports embryo from head to tail Segmental muscles that allow each muscle block to contract independently Dorsal hollow nerve cord (vs. arthropod's ventral nerve cord)
Indicate how the presence of "rusty" rocks in the geological record offered definitive evidence for the appearance of life.
Oxidized iron is red, meaning that in order for very old rocks in the geological record to be red, there must have been some life form photosynthesizing and releasing oxygen Starting around 2 billion years ago, there are red iron-rich rock deposits in the geological record, indicating that there was some life form No rocks containing oxidized iron before the great oxidation event
Discuss why plant oils and biodiesel fuel sources are a promising alternative to traditional fossil fuels
Plant oils - avoid adding carbon dioxide to the air and recycle atmospheric carbon (the sugars, starches, and cellulose from plants can be fermented into ethanol - created by plants absorbing carbon dioxide from the atmosphere) Biodiesel fuel sources - are created by photosynthesis and absorption of co2, ends up recycling co2 that is produced by the combustion of the fuel in cars, etc.; high energy content in some plant-based biofuels; bio-energy crops are under development that can grow on land that is not suitable for food production and without heavy fertilization (i.e., miscanthus giganteus)
Discuss why plant (but not animal) cells can tolerate hypotonicity.
Plants have cell walls, but animal cells do not, therefore animal cells will burst under hypotonic conditions while plant cells' strong cell walls helps them stay intact
Discuss the significance of the casparian strip.
Prevents water from flowing directly from the apoplastic pathway to the xylem vessels Regulates what enters into the cell by forcing water to diffuse into the cell through the endodermal cell wall Without it, plant would have no control over what minerals or chemicals flowed into the cells
Distinguish the functions of primary and secondary growth in roots and stems.
Primary growth (essential growth, vital to existence): elongation of shoots and roots - enables the plant to continuously seek sunlight (shoots) and water (roots) Secondary growth (increases strength and functionality): increase in girth of shoots and roots - enables plant to increase its strength and create more vascular tissue for water conduction and transport of nutrients
Identify the tissues involved in primary and secondary growth.
Primary: shoot apical meristem - dividing cells near shoot tips, new cells elongate and differentiate into primary tissues; root apical meristem - dividing cells near root tips, new cells elongate and differentiate into primary tissues Secondary: lateral meristems - dividing cells increase the diameter of the shoots and roots in eudicots
Indicate what distinguishes plants from other organisms.
Produce 20-50% of the oxygen we breathe Produce most of the chemically stored energy we consume as food and burn as fuel Produce a variety of useful chemicals
Summarize the two mechanisms that tomato plants use to defend themselves against caterpillars.
Produce chemicals to disrupt caterpillars' digestive system and attract wasps When a caterpillar feeds on a tomato plant, the leaf wound triggers the release of the hormone systemin which travels through the phloem to other plant parts and binds to a receptor in the plasma membrane The membrane lipids release the precursor to jasmonate, jasmonate is synthesized, then it triggers the expression of genes coding for proteinase inhibitor, inhibiting the digestion of the caterpillars When caterpillars wound the plant by feeding, the wound and chemicals in their saliva signal a transduction pathway that causes the synthesis and release of volicitin, which attracts wasps who lay their eggs in the caterpillars
Bacteria
Prokaryotes Inhabit common environments Microscopic unicellular organisms Can be producers, consumers, or decomposers Some can move but most lack motile structures Some aerobic, some anaerobic
Describe the role of proton pumps in the transport of nutrients across plant cell membranes, using uniporters, symporters or antiporters.
Proton pump: moves H+ out of the cytoplasm and up its concentration gradient to create an electrical gradient which is highly positive outside the cell and negative inside the cell, driving positively charged nutrients across the membrane Uniporter: only positively charged nutrients may pass the membrane alone Symport: transport of 2 ions together across the membrane because of the H+ chemical gradient Antiporters: H+ moving into the cell powers the movement of Na+ out of the cell
Distinguish between the hormonal response pathways that generate quick versus more delayed responses.
Quick response: hormones binding to plasma-membrane receptors (i.e., activate a proton pump) Delayed response: hormones that bind to internal receptors initiate a more delayed response - protein synthesis over a period of hours to days (diffusing through the membrane of the cell)
Explain how plant chemistry has been exploited to solve pervasive health problems like malaria.
Quinine from a South American tree bark kills plasmodium, which is the protozoan that female mosquitoes transfer when drinking blood and that causes malaria As plasmodium has evolved resistance to quinine, scientists have found other plants that have natural resistance to malaria - artemisinin from the artemisia plant has antimalarial properties
Distinguish between regulators and conformers.
Regulators: body regulates internal temperature according to changes in the environment, maintains the same temperature - i.e., thermoregulation Conformers: body temperature changes according to the external environment
Describe the biological basis for the expression: "One rotten apple spoils the whole barrel."
Ripe climacteric fruits release ethylene increasingly as they ripen, so ripe fruit can promote the ripening of another fruit because of the release of ethylene and the other fruit absorbing it
Describe the insights that patient SM and Phineas Gage provided into the functions of the amygdala and prefrontal cortex.
SM: lost her amygdala and was unable to feel fear, but could feel other emotions, indicating that the amygdala was essential for experiencing pain and fear Phineas Gage: had an accident that damaged prefrontal cortex and drastically altered his personality, indicating that the prefrontal cortex plays an important role in the formation of personality
Describe the role of the sensors, integrators and effectors in a negative feedback system.
Sensors: detect the changes in temperature or pH (sensing the blood is hot or acidic, etc.) Integrators: communicate this information to the brain and compare to normal state (blood temperature is compared to the set point, understands that a change needs to be made) Effectors: activated to return the condition back to the set point (activate heat loss mechanism) Once condition is returned back to the set point, negative feedback cancels the process
Compare the functions of the shoot, leaf, vascular and root systems of a plant.
Shoot: aboveground, specialized for photosynthesis and reproduction, consists of stems, leaves, flowers (angiosperms) Vascular: conduct water, dissolved minerals, and organic substances throughout the plant body Root: belowground, anchors the plant, provides structural support, stores carbohydrates, absorbs water and dissolved minerals from soil
Distinguish between short-term and long-term phototropic responses of plants.
Short-term: orient the plant towards a light source (plants leaning toward the sun) Long-term: plants grow into well-lit areas (i.e., branches growing across rivers to exploit a gap in the forest canopy)
Cnidarians (hydra, coral, sea anemones, jellyfish)
Simplest animals with specialized tissues, primitive nerve net Lack organ systems but have a nerve net that allows them to coordinate simple movements Mouth serves digestive and circulatory functions Gas exchange and secretion by diffusion through their skin (thin enough)
Cartilaginous fishes
Skeletons composed entirely of cartilage (endoskeletons)
Describe the timeline of the Great Oxygen Event and discuss the role of cyanobacteria.
Starting about 2.3 bya, atmospheric oxygen levels began to rise Until about 1.8 bya, most oxygen was absorbed by oceans and seabed rock between 1.8 and 1 bya, oxygen begins to leave the oceans and is absorbed by land surfaces and the ozone layer (meaning not a ton of atmospheric oxygen still) After about 900 mya, oxygen has saturated organic and inorganic matter and begins to accumulate in the atmosphere in large quantities Oxygen is only naturally produced by photosynthesis, and the only photosynthetic organisms around at this time were cyanobacteria, meaning that the rise in atmospheric oxygen is a result of the emergence of cyanobacteria
Describe the function of the stomata, and indicate how they open and close.
Stomata help the plant regulate transpiration by opening and closing to permit or prevent gas flow Stoma is in the center of two semi-circle-shaped guard cells that change shape with turgor pressure When K+ ions enter the guard cells, water follows down its concentration gradient into the cell, increasing turgor pressure and causing the guard cells to form a sickle shape and open in the middle When K+ ions leave the cells, the water follows down its concentration gradient and the cells lose turgor pressure and become more linear which closes off the opening
Describe how the water in the xylem facilitates the movement of sucrose into "sink" cells.
Sucrose is produced in the leaves and transported to the phloem Increased sucrose concentration decreases water potential in the phloem and pulls water from the xylem vessels Influx in water in the upper sieve tubes of the phloem increases turgor pressure and pushes the sucrose-rich sap down toward the roots because of water pressure From the roots, sucrose is transported out of the sieve tubes into root cells, which lowers turgor pressure, increases the water potential, and osmosis causes water to flow back into xylem vessels because with the sucrose molecules removed, there is more water in the sieve tube than in the xylem
Urochordata
Swimming larvae are motile and have a notochord
Distinguish the functions of the sympathetic and parasympathetic nervous systems.
Sympathetic: fight or flight - increase heart rate, dilate bronchi, increase blood pressure, increase blood circulation in skeletal muscle, decrease in skin, kidney, gastrointestinal tract Parasympathetic: rest and digest, decrease heart rate, contraction of bronchi, weak influence on blood pressure, increase of motility and secretion
Discuss what causes a neural membrane to become refractory.
The K+ channels open after the peak of the action potential and cause K+ ions to leave the cell and return it to its negative potential Is unable to generate a new action potential until it returns to its resting state
Explain how the brain determines which part of the basilar membrane is vibrating in response to a particular frequency of sound.
The cilia hairs are bent back and forth depending on the region of the membrane that is vibrating The bending of the hair cells trigger action potentials in afferent neurons, meaning that they are tuned to a particular sound frequency Frequency can be communicated by the time intervals between action potentials in afferent neurons Neurons stimulated by the hair movement project to the brain via the cochlear nerve which eventually gets them to the auditory cortex where they are processed
Explain how the brain discriminates between light and deep touch.
The frequency of action potentials increases as the intensity of the stimulus increases
Explain why K+ efflux is greater than Na+ influx across neuronal membranes.
There are more K+ non-gated channels than Na+ non-gated channels, meaning that it is easier for K+ to leave the cell than it is for Na+ to enter the cell (making the inside of the cell negative relative to the outside of the cell)
Explain the relationship between the micropyle, fertilized egg, endosperm, and fruit.
The sperm enters through the ovule's micropyle As a synergid is dying, it guides one sperm to the egg cell to fertilize it, and the other to the endosperm mother cell One sperm fuses with the egg to form a diploid zygote, the other fuses with the endosperm mother cell to nourish the embryo The fruit of a plant is its matured ovary that develops after the initial fertilization of the zygote; packaging structure for seeds
Distinguish between the electrical and chemical driving forces acting on a resting neuron membrane, and explain how they contribute to the resting membrane potential.
There is a concentration gradient caused by the increased concentration of K+ in the cell and Na+ out of the cell, meaning that it drives the two ions to follow their concentration gradient out of and into the cell, respectively To combat this, a pump must work to maintain the balance, otherwise the membrane potential would not be able to be maintained Concentration gradient drives K+ out of the cell and creates a negative gradient which works to pull K+ back into the cell and produce a membrane potential If cell is also permeable to Na+, the high concentration of Na+ outside of the cell will use a chemical gradient to pull Na+ into the cell This combines with the negative charge of the inside of the cell to create a stronger inward flux of Na+
Explain what is unusual about the meristematic tissue of grasses.
They lack apical meristems, and instead have meristems between mature tissues, just above ground level - growth occurs here, meaning that grass can grow even after animals have grazed or mowed
Explain why APs propagate more quickly in myelinated (vs unmyelinated) neurons.
They regenerate themselves at each node and jump from node to node instead of regenerating themselves at every single point along the axon Positive ions spread to the next node and cause depolarization which brings an action potential to the next node
Define the following terms: threshold potential, polarization, depolarization, repolarization, and hyperpolarization.
Threshold potential: the point where the membrane potential rapidly becomes less negative and the action potential is generated (must be depolarized to above the threshold potential) Polarization: membrane potential above 0 mV Depolarization: changes in the membrane potential caused by opening or closing ion channels, membrane potential becomes less negative (less polarized) Hyperpolarization: membrane potential becomes more negative Repolarization: restoring the polarized condition of a membrane after an action potential
Describe how the proprioceptive and vestibular systems contribute to movement, body awareness and balance.
Vestibular: enables sensing movement, i.e., motion, spatial orientation, balance Proprioceptive: stretch receptors help to control movement, keep track of where our body is in space, sense muscle force and effort, and maintain balance; baroreceptors: help indicate stretch of internal cavities; chemoreceptors indicate pH and other information about blood and cerebral spinal fluid Vestibular: senses speed/direction of movements Proprioception: responds to try and help people fall so they don't hurt themselves
Mollusks (clams, snails, octopuses)
Visceral mass contains digestive, excretory, reproductive system, and heart Locomotion through muscular head-foot Most have open circulatory system - blood in an open cavity that bathes the tissues
List the events involved in neurotransmitter release.
Voltage gated calcium channels open when the action potential arrives Neurotransmitters diffuse across the synaptic cleft and bind to receptor proteins The activation of those receptors causes ion channels to open or close and alter the flux of ions in the postsynaptic cell, changing the membrane potential of the postsynaptic cell (gate opening and letting sodium rush into the postsynaptic cell)
Explain how the water potential gradient provides the force that pulls water up through the plant body, driving transpiration.
Water potential becomes increasingly negative moving from the soil up to the atmosphere (roots, stems, leaves) Most negative water potential in the atmosphere causes the water to travel up the plant body (down concentration gradient) and undergo transpiration into the atmosphere Does not require ATP, no energy used
Explain how you can use tree rings to determine the age of a tree.
Xylem cell diameter changes throughout the growing season Spring growth usually results in large cells, while fall growth usually results in smaller cells, so years can be measured by tracking the size of cells in each ring
Name the two types of plant vascular tissues and their functions.
Xylem: dead; contains stacks of vessels and tracheids; distributes water and dissolved minerals from the roots to the rest of the plant, provides structural support for the plant Phloem: alive; transports food (sugars made during photosynthesis) from leaves downward to other tissues
Birds
hollow limb bones; reduced bony elements in wings, skull, vertebral column; massive flight muscles attached to sternum; high metabolic rate
Mammals
nurse their young (unlike other chordates); monotreme - young begin development in leathery shelled egg; marsupial - crawl out of mother's uterus early in development and latch onto a teat in the abdominal pouch where they continue development; placental - complete embryonic development in the uterus and are nourished through the placenta
Reptiles
tough, waterproof skin with keratins and lipids preventing dehydration; amniote eggs which survive and develop on dry land; uric acid as waste product for nitrogen metabolism
