Plant Lab

Plants LabSpring 2013

Radish Root Hairs

Question

• Newly-formed cells soon will differentiate into different types of cells and form tissues. Plant regions having undifferentiated cells are known as meristems. We find meristematictissues at root tips.

• Where else in a plant should you expect to find meristems?

Leaves

Dermal Tissue

Plant Crystals: Raphides

Plant Crystals: Druses

Question• Crystals in different plants occur as raphides

(sharp needles), druses (star shaped) and other forms. Most are composed of calcium oxalate.

• How might a plant benefit from having needles or other crystals in its leaves?

Lower Epidermis

Question

• Another way plants protect themselves against excessive water loss is by secreting a waxy sort of substance to form a cuticle on the surface of a leaf. The cuticle is quite apparent in some leaf peels and cross sections

• In which types of habitats do you think you’re most likely to find plants with significant cuticles?

Ranunculus Cross section

Xylem and Phloem

Plasmolysis

• Elodea leaves again!!

• This time concentrate on chloroplast

• Work in partners– One scope has water the

other has salt water

– Use the wet slide mount technique

– Wait 15 minutes for salt water drawing • While we wait lets move to

photosynthesis and respiration

Photosynthesis and Respiration• Recall from Window into a cell

• Plants contain chloroplasts and mitochondria

• While the chloroplasts are active during the day they are creating sugars in the form of glucose

• When the mitochondria are active they use the glucose (sugar) to produce energy in the form of ATP

Question

• Most living things require oxygen.

– How can we breathe during the winter months in temperate zones? How do polar organisms manage?

• Some people enjoy plants in a closed/sealed container called a terrarium.

– How can the plants thrive with no access to the outside air?

Plasmolysis

Before adding salt After adding salt

Why does this Happen? Osmosis

• Osmosis example animation:– http://www.stolaf.edu/people/giannini/flashanim

at/transport/osmosis.swf

– In addition to the molecules and other structures, cells contain lots of water. Water is made of two hydrogen's and one oxygen molecule

– Molecules are in constant motion. Molecules that are crowded into one area (higher concentration) will Spread out into an area of lower concentration

Elodea Osmosis Explanation

• Plant cell in salt water:– Water molecules Leave the cell

to the environment because it has a lower concentration due to the salt

– Result = cell membrane lacks water pressure and it appears to shrivel up

• Plant cell in water:– Water molecules Enter the cell

because the environment has higher concentration of water

– Result = cell membrane is pushed outward by higher water pressure, giving the appearance to be spread out

Starch and Plastids

• Crackers

• in finger bowl

– What color are the following items when Iodine is applied (iodine reacts with starch it turns blue-black)

• Potato

• Been

• Cornstarch

• sugar

Starch and Plastids

• Plastids are cells that store specific things

– Chloroplasts is a plastid that stores chlorophyll

– Amyloplasts are specific plastid and it stores starch grains

Amyloplasts

Reminders

• Lecture:

– Lecture Exam #1 Tuesday

• Lab:

– Quiz 5 – Take home quiz