Warm up

List the steps for germination of starchy seed.

The processes of germination begins with the absorption water. This causes the production of gibberellin acid, GA for short. The GA then causes the synthesis of amylases which is used to break down starch and make it into maltose. This maltose is then transported to the embryo and used for two different purposes. It could either be made into glucose (energy for the embryo) or polymerized to cellulose (for cell wall formation). The absorption of water will also form enzymes, triglycerides and phospholipids out of the stored proteins and lipids. Germination uses the food stored in cotyledons as an energy source until the developing shoot reaches the light and can begin to make its own food through photosynthesis.

 

Explain how flowering is controlled in long day and short day plants, including the role of phytochrome

Phytochrome  is affected by light and controls flowering.  Phytochrome exists in two forms Pf and Pfr. The P_fr form is the active form of phytochrome, while the P_r form is the inactive form of phytochrome. Sunlight is composed of more red light then far red, so the P_fr form is mostly active during the day, with the P_r form is mostly active at night.
 In long day plants, the active P_fr form is a promoter of flowering and so flowering is induced when the night period is less than a critical length and P_fr levels are high. In short day plants, the active P_fr form is an inhibitor of flowering and so flowering is induced when the night period is greater than a critical length and P_fr levels are low.

Warm Up: Plant Science Part Two!!!

1. Of what value are tubers, a type of stem modification, to the survival of a plant species?

Tubers are a modified plant structure that are enlarged to store nutrients. They are used by plants to survive the winter or dry months, to provide energy and nutrients for regrowth during the next growing season.

2. When moving a plant from one place to another, why is it important to leave original soil around the roots?

It is important to leave original soil around the roots of a plant when moving its location because the original soil will allow the plant to have a nice transition to its new environment. It lets it slowly adapt and become situated in the new location. If it were to be moved without any original soil, the change may be too drastic or fast for the plant to be able to process it and adapt. This might lead to a very sad death. 

3. What is the usual cause when a plant wilts?

The cause for a plant wilting is usually a lack of water in the plant's cells, which is means it has a lower turgidity. This reduces its ability to remain rigid or erect. The poor guy sadly wilts from thirst!

4. Explain when a seed would be a sink and when it would be a source

Source: produces and stores carbohydrates
Sink: consumes those carbohydrates
 The movement of carbohydrates occurs from where carbohydrates are made or have been stored, called a source, to where they will be stored or used, called a sink.

5. Why is it necessary that veins are relatively close together in the leaves?

Distance between veins shows how well the veins are supplying resources to the leaf. Plants with denser vein networks -- veins that are closer together -- are able to withstand higher levels of water loss and absorb more carbon.

More Plants! Warm up 2

Compare growth due to apical and lateral meristems in dicots

Growth in plants is brought about initially with cell division at the apical and lateral meristem.

Observation of shoot/root tips with light microscope reveals regions with cell in the various stages of mitosis. (Cell division, reproduction)  

This growth process adds length to the stem or root

Secondary growth added by the Lateral meristem has two types

1.       Vascular cambium that produces secondary xylem and phloem

2.       Cork cambium produces some of the bark layer of the stem

Explain the role of Auxin in phototropism

If light is scares because an area is crowded with plants or for some other reason, a plant needs to grow towards the light so it can get as much of it as possible.

Auxins are plant hormones that cause positive phototropism of the plant shoot and seedings

Explain how water us carried by transpiration stream, including the structure if xylem vessels, traspirational pull, cohesion, adhesion and evaporation

Plants!!! Warm up

Outline the differences (5) between the monocots and dicots

Feature	Monocots	Dicots
Venation	Parallel venation	Net- like venation
Number of Cotyledons	Two	One
Floral Organs	Petals in multiples of three	Petals in multiple of 4 & 5
Roots	Fibrous adventitious	Tap root with branching laterals
Leaf Mesophyll	Spongy	Palisade and spongy
Vascular Bundle Arrangement	Arranged in rings. Divided into cortex and stele	Bundle, no particular order

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

Stem modification

Bulbs: Onions and lilies

·         Short vertical underground stems

·         Many fleshy highly modified leaves for the storage or nutrients

·       Can produce new plants by bulb division or development of one of the many auxiliary buds

Horizontal stems- runners

·         Spread out from the main body of the plant

·         At the point the stem touches the ground, a new root forms

·         Asexual reproduction, if a runner id broken it can establish its self as its own plant

·         Adaptation for finding water

Cacti

·         Leaves are reduced to spines to prevent water loss in transpiration

·         The stem is enlarges for storage of water

·         The stem carries out photosynthesis

Root tip modification

 Tuber/ Potato 

·         The potato is an underground modification of the root tip

·         The ‘eaten potato’ contains the carbohydrate and protein stores for the growth

·         Auxiliary buds

Tap Root modification

·         Function: Storage of water

·         Sandy soils

Some fun things about Photosynthesis

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




Explain photophosphorylation in the terms of chemiosmosis.
Photophosphorylation is the production of ATP using the energy of sunlight. The process of chemiosmosis makes photophosphorylation possible. Chemiosmosis is the movement of ions across a selectively permeable membrane and down a concentration gradient. During photosynthesis, light is absorbed by cholorphyll molecules in photosystems. Electrons within these molecules are then raised to a higher energy state; they become excited. There is a high concentration of H+ from the pumping of protons. Then, H+ accumulates in the thyhlakoid space. Protons diffuse through ATP synthase where they reduce ADP to ATP.

State the final products of the two photosystems involved in the light-dependent reactions of photosynthesis.
 The final products of the two photosystems involved in light-dependent reactions of photosynthesis are ATP and NADPH.

How are the products of the light-dependent reaction important to the light-independent reaction?
The products (glucose, amino acids, organic compounds, ATP, and NADPH)of the light-dependent reaction are very important. The light-independent reactions use these products in order to fuel their processes and carry out the Calvin Cycle. It is its reactants.

Chemiosmosis in Phosphorylation

Describe chemiosmosis as it relates to oxidative phosphorylation.

Chemiosmosis involves the movement of protons (hydrogen ions) moving across a membrane (down its concentration gradient) to provide energy so that oxidative phosphorylation can occur. Oxidative phosphorylation is a metabolic pathway that uses energy released by the oxidation of glucose to produce ATP.

Although the many forms of life on earth use a range of different nutrients, almost all carry out oxidative phosphorylation to produce ATP, the molecule that supplies energy to metabolism. This pathway is probably so pervasive because it is a highly efficient way of releasing energy, compared to alternative fermentation processes such as anaerobic glycolysis.

The Fabulous Role of Oxygen

Role of Oxygen in Cellular Respiration

Without oxygen, cellular respiration could not occur because oxygen serves as the final electron acceptor in the electron transport system. The electron transport system would therefore not be available. It is part of the process!

Glycolysis can occur without oxygen. Although glycolysis does not require oxygen, it does require NAD+. Cells without oxygen available need to regenerate NAD+ from NADH so that in the absence of oxygen, at least some ATP can be made by glycolysis.

Role of Oxygen in Photosynthesis

Oxygen is the by-product of a water molecule breaking down to supply photosystem II with electrons in the very beginning of photosynthesis.