BIOLOGY 111 LAB PRACTICAL 2 TAMU EXAM QUESTIONS AND ANSWERS 2024.

what is the primary means by which chemical energy is added to the biosphere? Photosynthesis Where does photosynthesis occur? thylakoid membranes in the grana stacks of chloroplast What are the main photosynthetic pigments? chlorophyll A, B, carotene, and xanthophyll What is different between the main photosynthetic pigments? they each absorb a different wavelength which is important to the survival of plants throughout seasons What is a byproduct cellular respiration? carbon dioxide What do photosynthetic cells use solar energy for? to convert, or fix, atmospheric carbon dioxide into carbohydrates, it splits the water molecules and releases electrons to make ATP out of Photochemical reactions are ___________ solar powered Biochemical reactions do not need__________ light What do photochemical reactions accomplish? they split water, energize electrons in pigment molecules and release oxygen molecules What do Biochemical reactions accomplish? they use the energy generated by the photochemical reactions to fix carbon to sugars What does photo-system 1 do? light energy is absorbed which excites the chlorophyll which causes electrons to pass to a terminal acceptor molecule. Photosystem 1 is filled by electrons passed down the electron chain from photosystem 2. electrons from photosystem 1's terminal electron acceptor enter a second electron transport chain where they reduce NADP to NADPH What does photosytem 2 do? solar energy is absorbed, excites electrons in the chlorophyll to a higher energy level, these electrons are trapped by primary electron accpetors and are replaced by electrons extracted from water releasing oxygen as a by- product, electrons from photosystem 2 pass down the electron transport chain, yielding energy to generate ATP How is it possible to measure the effect of light intensity on electron transport? by substituting NADPH with DPIP (2,6-dichlrorophenolindophenol) What does DPIP do? In it's oxidized state DPIP is blue, but when it accepts electrons it becomes clear the greater the reduction of dPIP the more clear the solution, and the greater absorbance when measured How did the distance of the light effect the absorbance measured? The closest plant- had too high intensity and was denatured the middle plant- optimum the farthest- to far and the reaction didn't happen at a high enough rate / Why do we see color? because objects contain pigments that selectively absorb some wavelengths and reflect others What is an action spectrum? charts the effectiveness of different wavelengths of light on photosynthesis What were the spinach leaves aspirated with and why? in sodium bicarbonate, and its to remove trapped gases from the intercellular spaces What are the reasons for the spinach disks sinking and floating? they sink when aspirated and float when photosynthetic activity fills the intercellular spaces with oxygen, the faster the rate of photosynthesis the quicker the leaf, disks float What do photosynthetic pigments determine? which wavelengths of light are used for photosynthesis what is the shape of chlorophyll? large ring molecule with non polar hydrocarbon tail What is the significance about the shape of the pigments? the hydrocarbon portion of the molecule anchors the pigments to the thylakoid membrane within the chloroplast What is used to identify the pigments found in spinach? silica gel chromatography How do you calculate a chromatograph's Rf value? distance moved by pigment/ distance from origin to solvent front what can cause one particle to move farther than another during chromatography? - polarity' -size what is the simplest form of cell division? binary fission How does binary fission begin? with the replication of the circular DNA strand What is the division of the cytoplasm known as? cytokenesis How is Eukaryotic DNA arranged compared to Prokaryotic DNA? eukaryotes have linear DNA while prokaryotes have circular DNA What is mitosis? a form of cellular reproduction that results in two genetically identical daughter nuclei -embryonic development -asexual reproduction -regeneration -maintenance -repair of tissue What is Meiosis? results in the formation of haploid gametes, or sex cells What phase occurs immediately after Mitosis? G1 or the first gap of interphase What happens during the G1 phase? primary growth, cell doubles in size organelles are duplicated and ribosomes, RNA, enzymes are synthesized What happens to a cell at a restriction point? cells that lack threshold levels of critical cellular processes exit the cell cycle and enter the G0 state as non dividing cells What happens during the S phase? DNA replication What are sister chromatids? identical strands of DNA What joins sister chromatids together? a centromere What happens during G2? the spindle forms centrioles replicate and become visible mitochondria replicate chromosomes begin to condense and coil