Biology 160 Photosynthesis

How many chloroplasts does a mesophyll usually have?

A mesophyll usually has 30 to 40 chloroplasts.

What are reaction-center complexes made up of?

1. A pair of special chlorophyll "A" molecules 2. A molecule called the primary electron acceptor.

What can chlorophyll release after absorbing light energy?

1. Light 2. Heat

What are the two types of photosystems?

1. Photosystem I 2. Photosystem II

What happens to electrons when they absorb and convert light energy?

1. Pigment molecules (like chlorophyll) absorb the photons and jump to a high-energy state 2. They then release excess heat as a waste from converting light energy and drop down to a low-energy state.

How many stages does photosynthesis occur in?

2 stages: -light reaction -Calvin cycle

What is a photon?

A photon is a bundle of distinctive individual packets of energy. The shorter the wavelength of light, the more energy that wavelength has in its photons.

What is a granum?

A granum is a stack of thylakoids that are connected to each other, grana for plural.

What is a photosystem?

A photosystem is a group that is clustered together made up of light-harvesting complexes which surrounds a reaction-center complex.

What is a wavelength?

A wavelength is the distance between one electromagnet wave and another wave.

What are the general inputs and outputs of the Calvin cycle of photosynthesis?

ATP + NADPH + CO2 = (ADP + P) + NADP+ + glucose

What are autotrophs?

Autotrophs are organisms which can produce their own foods. Ex: plants

Why does ultraviolet radiation cause sunburns and skin cancer?

Because their wave lengths are so short that they carry enough energy which is able to damage molecules like proteins and nucleic acids.

How can we explain why black pigments are so hot on a sunny day?

Black pigments absorb all wavelengths, meaning that there is a lot of light energy conversions occurring, releasing massive amounts of excess heat as a result.

What becomes reduced and oxidated in photosynthesis?

CO2 gets reduced into glucose. Water gets oxidated into O2.

What is carbon fixation?

Carbon fixation is when CO2 is used to become apart of an organic compound.

What are carotenoids?

Caroteniods are pigments that are shades of yello and orange that co-exist with the chlorophyll pigments that are green. Show in leaves when chlorophyll breaks down in the fall.

How do carotenoids protect plants?

Carotenoids are responsible for photoprotection by absorbing and then releasing excess light energy that would have damaged the plant.

What is the chlorophyll?

Chlorophll is a light-absorbing pigment in chloroplast that has a major role in transforming solar energy (sunlight) into chemical energy.

What color of wavelengths does chlorophyll "a" usually absorbs?

Chlorophyll A generally absorbs blue-green and red light.

What color of wavelengths does chlorophyll "b" usually absorbs?

Chlorophyll B generally absorbs blue and orange light.

Where are the chlorophyll molecules located in a chloroplast?

Chlorophyll molecules are located on the membrane of the thylakoid.

What are chlorophyll molecules?

Chlorophyll molecules are molecules which are responsible for sunlight absorption.

What does electromagnetic energy refer to?

Electromagnetic energy refers to sunlight or radiation.

What is fluorescence?

Fluorescence is a reddish after-glow from the result of chlorophyll molecules emitting photons of light after absorbing said protons (chlorophyll electrons got excited from the photons, raising them to a high-energy state).

Where do the separate atoms of the previous H2O go during the light reaction cycle?

H+ (hydrogen ions/protons): -H+ stays in the thylakoid space Oxygen atom: -immediately joins another oxygen atom to create O2 Electrons: -get charged up by photons and go through the photosystems to create ATP and NADPH

What are heterotrophs?

Heterotrophs are organisms which cannot make their own food but need to eat other plants or animals, or decompose other material.

What happens in the light reaction stage of photosynthesis?

Light reaction occurs in the thylakoids of the chloroplast. Light energy is absorbed by the chlorophyll molecules in the thylakoid membrane. - Light energy is used to power the transfer of electrons and protons (H+) from water to the electron acceptor NADP+, reducing it into NADPH. Water enters into the plant through the roots of the plant. - H2O is split, creating O2 as waste. Chemical energy is produced as ATP an NADPH, which is then used in the Calvin Cycle.

What are light-harvesting complexes made up of?

Light-harvesting complexes are made up of many pigment molecules which are bound to proteins which work together to absorb light like a TV antenna absorbing signals.

What do light-harvesting complexes do?

Light-harvesting complexes gather/absorb photons then pass them on to other light-harvesting complexes until it gets to the reaction-center complex.

What are mesophyll cells?

Mesophyll cells are the cells of mesophyll which have millions of chloroplasts that work on absorbing sunlight (solar energy) for photosynthesis.

What is the mesophyll?

Mesophyll is the green tissue like filling on the inside of a leaf.

What are photoautotrophs?

Photoautotrophs are organisms which use light energy to produce their own foods.

What is photophosphorylation?

Photophosphorylation is the term that refers to the chemiosmotic production of ATP due to the input of light energy to drive the process.

What type of process is photosynthesis?

Photosynthesis is a redox process like cellular respiration.

What is photosynthesis?

Photosynthesis is the process that plants use to take in sunglight, water, and air (CO2) to produce O2, glucose and other organic molecules.

Which organelle does photosynthesis take place in?

Photosynthesis takes place in the chloroplast, an organelle in plant cells.

What order do the photosystems go in when the light reaction cycle is occurring?

Photosystem II goes first Photosystem I goes second.

What time of day do some plants usually have their Calvin cycle activated and why?

Some plants only have their Calvin cycle occur during the daytime to efficiently receive the product of the light reaction stage of photosynthesis.

How do the photosystems help in creating ATP and NADPH?

Starting with photosystem II: -an electron from the chlorophyll's "A" molecule get's excited by the photon, increasing it's energy state - the primary electron acceptor then recieves the high-energy electron and sends it through the electron transport chain Electron transport chain: -the high-energy electron delivered to the electron transport chain from photosystem II goes down the chain -as the electron goes through the chain, energy is released to create ATP -the photon charged electron then gets passed to photosystem I Photosystem I: - more photons charge the electrons once it gets to photosystem I and increases it's energy levels again - the primary electron acceptor in photosystem I again accepts the electron - the electron then gets accepted by NADP+ + H to create NADPH

What is the stomata?

Stomata are tiny pores on leaves where carbon dioxide CO2 can enter.

What are the general inputs and outputs of the light reaction stage of photosynthesis?

Sunlight + water + NADP+ = ATP + O2 + NADPH

What happens in the Calvin cycle stage of photosynthesis??

The calvin cycle occurs in the stroma of the chloroplast. CO2 is absorbed through the stomata, tiny pores on the leaf. - CO2 becomes what makes up glucose (CARBON FIXATION), - NADPH from the light reaction stage reduces the carbon, - ATP from the light reaction stage powers steps of the Calvin cycle. The used NADPH oxidates and turns into NADP+ again. The ATP turns into ADP + P. Both are then used in the light reaction stage of photosynthesis again.

What is the electromagnetic spectrum?

The electromagnetic spectrum is the full range of electromagnetic wavelengths ranging from the short gamma rays to the extremely long radio waves.

What is the source of the electrons that are moving through the photosystems to NADPH?

The electrons come from water (H2O) when it becomes oxidized and splitting up all the molecules into: -2 electrons -2 hydrogen ions -1 oxygen atom

What is the pair of special chlorophyll "a" molecules?

The pair of special chlorophyll "a" molecules are responsible for passing photon charged electronss (packets of energy) to the primary electron acceptor.

What does the photosystem take place in?

The photosystem is the first step in the light reaction cycle of photosynthesis.

What is the primary electron acceptor?

The primary electron acceptor is a molecule that is able to accept electrons and become reduced.

What is the range of visual light on the electromagnetic spectrum?

The range of visual light on the electromagnetic spectrum is between 380 nm to 750 nm.

What is the stroma?

The stroma is the thick fluid that fills up the chloroplast.

What else does the thylakoid membranes do?

The thylakoid membranes also convert light energy into chemical energy which is used in the stroma to make sugar.

What is the thylakoid space?

The thylakoid space is the space within the thylakoid.

What are thylakoids?

Thylakoids are membrane bounded sacs which can connect to each other thylakoids.

Where are the reactants of photosynthesis absorbed on a plant?

Water gets absorbed through the roots. Sunlight (solar energy) gets absorbed by the chlorophyll. Air (CO2) enters the plant by the stomata.

What reactant becomes O2 by the end of photosynthesis?

Water transforms into O2 with the process of photosynthesis, where the hydrogen atoms would become apart of glucose at the end.