8/3/2019 Bulla Exam 1 Study Guide

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Biology Lab Study Guide

The Black Box:

y Scientific Method1. Observe

2. Educated Guess (hypothesis)

3. Prove (experiment)

4. Data/results/conclusion

y Hypothesis:This is a tentative answer to the question: a testable explanation for what was observed.

The scientist tries to explain what caused what was observed.

y Control group:In a test or trial, a group that does not receive the new treatment being studied and which

is compared to the group that does receive the new treatment

y Experimental group:The group where the experimental procedures are performed

y Controls/experimental groups are used because it can be difficult to avoid confoundingvariables.

Osmosis, Diffusion, Plant Cells and Tonicity:

y Diffusion:the process by which molecules spread from areas of high concentration, to areas of low

concentration. When the molecules are even throughout a space it is called equilibrium.

Ex: Gas exchange for photosynthesis carbon dioxide from air to leaf, oxygen from leaf

to air.

y Osmosis:Water will move in the direction where there is a high concentration of solute (and hence

a lower concentration of water.) the diffusion of water (across a membrane)

Ex: Absorption of water by plant roots.

Hypertonic: *water moves out of the cell*

The word HYPER means more; in this case there are more solute (salt) molecules

outside the cell, which causes the water to be sucked in that direction.

Ex: In plant & animal cells, the central vacuole loses water and the cells shrink, causing

wilting and then cell may die.

Hypotonic: *water moves into the cell*

The word HYPO means less, in this case there are less solute (salt) molecules outsidethe cell, since salt sucks, water will move into the cell. The cell will gain water and grow

larger.

Ex: In plant cells, the central vacuoles will fill and the plant becomes stiff and rigid, the

cell wall keeps the plant from bursting in animal cells, the cell may be in danger of

bursting, organelles called CONTRACTILE VACUOLES will pump water out of the cell

to prevent this.

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Isotonic: *water goes in both directions*

If the concentration of solute (salt) is equal on both sides, the water will move back in

forth but it wont have any result on the overall amount of water on either side.

ISO means the same

y Water will diffuse out of the bag since the water potential is higher in the bag and watermoves from areas of higher water potential to areas of lower water potential.

y Iodine turns dark in the presence of starchy A change in color indicates the presence of reducing sugars.

Microscopy

y Parts and function of the MicroscopeEyepiece Lens: the lens at the top that you look through. They are usually 10X or 15X

power.

Tube: Connects the eyepiece to the objective lenses

Arm: Supports the tube and connects it to the base

Base: The bottom of the microscope, used for supportIlluminator: A steady light source (110 volts) used in place of a mirror. If your

microscope has a mirror, it is used to reflect light from an external light source up

through the bottom of the stage.

Stage: The flat platform where you place your slides. Stage clips hold the slides in

place. If your microscope has a mechanical stage, you will be able to move the slide

around by turning two knobs. One moves it left and right, the other moves it up and

down.

Revolving Nosepiece or Turret: This is the part that holds two or more objective lenses

and can be rotated to easily change

y Prokaryotes:-No nucleus

-no membrane bound organelles

-bacteria

y Eukaryotes:-nucleus

-membrane bound organelles

-animals

-plants

y Both:-cell wall-cytoplasm

-ribosomes

-DNA

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Flowering Plants:

Leaves serve:

1. manufacture food for the plant

2. store protein and other plant foods

3. keep the plant cool in hot water

Root Function:

1. store food for plant

2. hold plant firmly in the ground

3. take up plant food and water from the soil

Stem function:

1. carry plant food and water through the veins

y Xylem is woody tissue that carries water and minerals throughout the plant and providesthe plant with mechanical support. In leaves, flowers, and stems, xylem is present along

with phloem.

y Phloem is tissue that carries sugars and other nutrients from the leaves to cells forconsumption or storage. The hard xylem is usually on the inner side of the plant tissue

and the softer phloem is on the outer side where it is crushed and pushed outward as new

phloem is formed in the growing process.

Photosynthesis:

The process by which green plants and some other organisms use sunlight to synthesize

foods from carbon dioxide and water.

y Photosynthesis occurs in the leaves of plants, more precisely in the chloroplast