Chapter 8: Photosynthesis

What are heterotrophs?

"consuming others" - unable to make own food - biosphere's consumers (example: humans)

What are autotrophs?

"self feeders" - produces organic molecules from CO2 - ultimate source of organic compounds (example: plants)

What is the importance of NADP+

- "electron acceptor" - first cousin to NAD+ - functions as an electron carrier in cellular respiration - difference between NADP+ and NADPH is by the presence of an extra phosphate group in the NADP+ molecule. -

What are the two stages of photosynthesis?

1. The light reactions which involve the capture of light energy and its insertion in NADPH and ATP. It's the stage that involves light absorbing pigments such as chlorophyll and produces oxygen by the photolysis (the decomposition or separation of molecules by the action of light) of water. An electron transport chain produces NADPH directly, and ATP indirectly through a proton gradient that it sets up as happens in mitochondria. 2. Calvin cycle which utilize that energy in NADPH and ATP to build glucose also using (fixing) carbon dioxide from the atmosphere. - the calvin cycle was sometimes referred to as "dark reactions" because none of the steps requires light directly.

Which wavelengths of light are absorbed by chlorophyll a? Which are reflected?

435nm. violet blue and red works best for photosynthesis.

What is the equation for photosynthesis?

6CO2 + 6H2O ------> C6H12O6 + 6O2 Where: CO2 = carbon dioxide H2O = water Light energy is required C6H12O6 = glucose O2 = oxygen

What energy carrying molecules are made in light reactions?

ATP, NADPH NADPH - acts as "reducing power" that can be be passed along to an electron acceptor

What is the role of ATP in the cell? How does it get used? How does it get replaced?

Adenosine triphosphate, or ATP, is the energy currency of life, the way that individual cells store and use chemical energy. ATP get used with energy.

Compare and contrast aerobic and anaerobic respiration.

Aerobic respiration- a process that uses oxygen - occurs in most cells - high amount of energy released (36-38 ATP molecules) - stages: glycolysis, krebs cycle, etc - site of reaction: cytoplasm and mitochondria - reactants: glucose and oxygen - combustion: complete - doesn't produce ethanol or lactic acid Anaerobic respiration- a process that doesn't use oxygen - occurs in most prokaryotes - low amount of energy released (2-36 ATP molecules) - stages: glycolysis, krebs cycle, etc - site of reaction: cytoplasm - reactants: glucose - combustion: incomplete - produces ethanol or lactic acid

What is the chloroplast structure?

Be able to draw/ the parts where photosynthesis happens. Know where protons build up. Draw ATP synthase enzyme facing the correct side of the correct membrane.

In the light reactions, after the first electron leaves from chlorophyll a, what is the path of the next electron?

H2O --> p system 2 --> p system 1 --> NADP+

What gas gets released during the light reactions?

In these light-dependent reactions, some energy is used to strip electrons from suitable substances, such as water, producing oxygen gas. Furthermore, two further compounds are generated: reduced nicotinamide adenine dinucleotide phosphate (NADPH) and adenosine triphosphate (ATP), the "energy currency" of cells.

What gets reduced in photosynthesis?

Photosynthesis transfers electrons from water to energy-poor CO2 molecules, forming energy-rich sugar molecules. This electron transfer is an example of an oxidation-reduction process: the water is oxidized (loses electrons) and the CO2 is reduced (gains electrons).

What is the difference of cellular respiration and photosynthesis?

Respiration- Respiration is the breakdown of glucose to make energy using oxygen. Photosynthesis- Photosynthesis is the process through which plants make food for themselves in form of glucose. DIFFERENCE BETWEEN PHOTOSYNTHESIS AND RESPIRATION:- FORMULA Respiration:- C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy Glucose + Oxygen = Carbon dioxide + water Photosynthesis:- 6CO2 + 6H2O ------> C6H12O6 + 6O2 Carbon dioxide + water = Glucose + Oxygen 2. TIME OF PROCESS Respiration:- It is a process that is not timely and is done in both day and night Photosynthesis:- Photosynthesis use energy from the sun to make glucose and oxygen in the day. 3. GLUCOSE USAGE Respiration:- Animals and human use glucose and oxygen to carry out respiration Photosynthesis:- Plants produce glucose and oxygen to carry out respiration. 4. CARBON DIOXIDE Respiration:- In respiration, carbon dioxide is exhaled where as oxygen is inhaled by living beings Photosynthesis:- In photosynthesis, carbon dioxide is inhaled during day and oxygen is exhaled where as in night plants inhale oxygen and exhale carbon dioxide.

Why is exposure to salt water bad for the human body?

Salt water is hypertonic fluid. If you're consuming seawater, the results of osmosis are spectacularly disastrous. The salinity of seawater is almost four times that of our bodily fluids. If gone unchecked, the net transfer of water from the inside of your cells to the outside will cause the cells to shrink considerably -- and shrinkage is never good.

What happens to chlorophyll a molecule that gets a photon of light? What are all of the other pigments in a photosystem for?

The energy from the light excites an electron from its ground energy level to an excited energy level (Figure 19.7). This high-energy electron can have several fates. p162

Explain why plant cells "prefer" being in hypotonic solutions and animal cells don't.

The reason plants prefer hypotonic environments is so that the plant cells will soak up more water through diffusion which in turn would be stored in specialized cells such as vacuoles. Animals don't have cell wall. Nothing prevents them from swelling until they burst when placed in hypotonic solution.

Explain how the shape of enzymes affects function.

The shape alters the enzyme's active site, which can make it unable to catalyze the reaction it's intended to.

What are the major structures of the leaf that are important in photosynthesis? (stomata, veins, mesophyll)

stomata- where carbon dioxide enters the leaf, and oxygen exit through microscopic pores. veins- where water is absorbed and delivered to. mesophyll- where chloroplasts are found.