Explain the role of auxin in phototropism

Phototropism is the growing or turning of an organism in response to a unidirectional light source
Auxins (e.g. IAA) are plant hormones that are produced by the tip of a shoot and mediate phototropism
Auxin makes cells enlarge or grow and, in the shoot, are eradicated by light
The accumulation of auxin on the shaded side of a plant causes this side only to lengthen, resulting in the shoot bending towards the light
Auxin causes cell elongation by activating proton pumps that expel H+ ions from the cytoplasm to the cell wall
The resultant decrease in pH within the cell wall causes cellulose fibres to loosen (by breaking the bonds that hold them together)
This makes the cell wall flexible and capable of stretching when water influx promotes cell turgor
Auxin can also alter gene expression to promote cell growth (via the upregulation of expansins)

Explain how water is carried by transpiration stream, including the structure of xylem vessels, transportational pull, cohesion, adhesion, and evaporation

Some of the light energy absorbed by leaves changes into heat, converting water in the spongy mesophyll into vapor
This vapor diffuses out of the stomata and is evaporated, creating a negative pressure gradient in the leaf
New water is drawn from the xylem (mass flow), which is replaced by water from the roots (enters from soil via osmosis)
The flow of water through the xylem from the roots to the leaf is called the transpiration stream
Water rises through xylem vessels because of two qualities:
Cohesion:  Water molecules are weakly attracted to each other via hydrogen bonds
Adhesion:  Water molecules form hydrogen bonds with the xylem cell wall
These properties create a suction effect (or transpiration pull) in the xylem
The xylem has a specialized structure to facilitate transpiration:
The inner lining is composed of dead cells that have fused to create a continuous tube
These cells lack a cell membrane, allowing water to enter the xylem freely
The outer layer is perforated (contains pores), allowing water to move out of the xylem into the leaves
The outer cell wall contains annular ligin rings which strengthens the xylem against the tension created by the transpiration stream

Compare growth, due to apical and lateral meristems in dicots

Apical Meristems
Occurs at the tips of roots and shoots
Responsible for primary growth
Develops into primary xylem and phloem
Produces new leaves and flowers

Lateral Meristems
Occurs at the cabium
Adds lateral growth to stem (Increase width)
Responsible for secondary growth
Produces secondary xylem and phloem
Produces bark on trees

Similarities in close they are composed of totipotent cells (Like stem cells)
and the are found in dicots

Identify and describe modifications of roots, stems, and leaves of different plants. Give one example of each.

Storage roots:  Modified roots that store water or food (e.g. carrots)
Stem tubers:  Horizontal underground stems that store carbohydrates (e.g. potato)
Bulbs:  Modified leaf bases (may be found as underground vertical shoots) that contain layers called scales (e.g. onion)

Outline the differences between monocotyledons and dicotyledons

The leaf veins of a monocotyledons have parallel venation while dicotyledons have reticulated venation. Monocotyledons have one cotyledon while dicotyledons have two. Monocotyledons have fibrous adventitious roots and dicotyledons have top roots with lateral branches. Monocotyledons have floral organs that appear in multiples of three while dicotyledons have floral organs that appear in multiples of four and five. The pollen in monocotyledons has single pores while the pollen in dicotyledons has three pores.

Draw and label a diagram showing the structure of a chloroplast as seen in electron micrographs

State the final products of the two photosystems involved in the light dependent reactions of photosynthesis

There are two final products from both photo system the are nadph and ATP which will both be used later in the Calvin cycle

Explain photophosphorylation in terms of chemiosmosis

As the electrons cycle through the electron transport chains located on the thylakoid membrane, they lose energy
This free energy is used to pump H+ ions from the stroma into the thylakoid
The build up of protons inside the thylakoid creates an electrochemical gradient
The H+ ions return to the stroma via the transmembrane enzyme ATP synthase, which uses the potential energy from the proton motive force to convert ADP and an inorganic phosphate (Pi) into ATP

Why do plants need both mitochondria and chloroplast?

Plants need both in order to produce as much energy as possible. They are dependent on photosynthesis to produce glucose, but a majority of energy made in the cell is more efficiently produced in the mitochondria.

Outline the affect of temperature, light intensity, and carbon dioxide concentration on the rate of photosynthesis.

Carbon dioxide and light intensity have relatively the same affect on photosynthesis. With both, if they aren't present, there is no way for photosynthesis to occur. As both increase the rate of photosynthesis increases in a rather linear way. Eventually the chloroplast reaches maximum production and it doesn't matter how much more they increase because the chloroplast can't work any faster
Temperature has a different affect. As it increases originally the graph increases, then it peaks. After the peak, the rate takes a nosedive. As the temperature continues to increase, enzymes begin to denature. This curses the rate of photosynthesis to stop completely

You have a leaf from each of two very different plants. One leaf has more pigments Than the other. Which leaf would have the greater photosynthetic rate, assuming all affecting factors are equal? Why?

The one with more pigments would have a higher rate of photosynthesis

Because it is more capable of accepting light because it has more pigments

What is the role of Oxygen in the ETC?

Oxygen is the final electron acceptor along the Electron Transport Chain. It then goes to bind the two Hydrogen atoms to create a water molecule.

Describe cheiosmosis as it relates to oxidative phosphorylation.

As Hydrogen begins to become very concentrated in the outer membrane of the mitochondria, it starts to travel back across the membrane via the enzyme ATP Synthase. This enzyme uses the energy from the flow of protons through it to bind inorganic phosphate molecules to ADP molecules creating ATP.

Explain the process of cellular respiration. (Excluding ETC)

1: Glycolysis ("splitting of sugar"): This step happens in the cytoplasm.

One Glucose (C6H12O6) is broken down to 2 molecules of pyruvic acid. Results in the production of 2 ATPs for every glucose.

2: Linked Reaction: Pyruvic Acid is shuttled into the mitochondria, where it is converted to a molecule of Acetyl CoA for further breakdown. Acetyl CoA is a two carbon molecule.

3: The Krebs Cycle, or Citric Acid Cycle: Occurs in the mitochondrial matrix.

Acetyl CoA and Oxaloacetate bind together to become citrate. This 6 Carbon molecule under goes Oxidative Decarboxylation twice, the Substrate level ATP formation, then two oxidations to form 2 ATP, 2 FAHD2, 4 CO2, and 6 NADH+H+

4. The Electron Transport Chain: occurs a long the inner membrane of the mitochondria

The hydrogen carriers NADH+H+ and FADH2 provide electrons to the electron transport chain on the inner mitochondrial membrane and push hydrogen protons outside the inner mitochondrial membrane to a level of high concentration
As the electrons cycle through the chain they lose energy, which is used to translocate H+ ions to the intermembrane space (creating a more concentrated gradient)
The hydrogen ions return to the matrix through the transporting enzyme ATP synthase, producing multiple ATP molecules in a process called chemiosmosis
Oxygen acts as a final electron acceptor for the electron transport chain, allowing further electrons to enter the chain
Oxygen combines the electrons with H+ ions to form water molecules
The electron transport chain produces the majority of the ATP molecules produced via aerobic respiration (~32 out of 36 ATP molecules per molecule of glucose)

Identifying the Structure warm up

This structure is a mitochondria. The mitochondria is best adapted to convert pyruvate molecules into ATP. This is achieved by maximizing surface area inside the cell. There are little villi like tendrils called cristae that help aid in increasing the surface area for the Electron Transport Chain, and there are open spaces, called matrices, in which the krebs cycle takes place

What are the products of the Krebs Cycle? Glycolysis

Products of the Krebs Cycle:
2 ATP
2 FADH2
4 CO2
6 NADH + H+

Products of Glycolysis
4 ATP produced (2 are used in the process for a net gain of two)
2 NADH+ H+
2 pyruvate molecules

What is substrate- level phosphorylation

A process in the Krebb's Cycle in which ATP is produced via the addition of an inorganic Phosphate molecule to ADP.

What is Oxidative Decarboxylation

Oxidative decarboxylation is a process in the krebbs cycle of cellular respiration in which a citrate molecule or a Alpha ketagluterate  molecule loses hydrogen molecule and carbon dioxide.