Lab 4: Plant Physiology

Lab 4: Plant Physiology 

Part 1: Water Absorption and Transport in Plants 

Introduction 

Root Hair - Water is first absorbed into this structure of the root just before reaching the ‘pipeline of xylem. 

• Continuous column of water. Reasons (why water is pulled up): 

• Cohesion-tension model 

1. Cohesion - Occurs because hydrogen bonding and waters polar nature: water sticks to the side of the vessels 

2. Tension - Due to transpiration that acts as to evaporate water (which is replaced by other water molecules) 

Transpiration - The act of evaporation in plants through stomata cells on leaves. 

Uptake of Water

Exercise 1: Uptake of water by root hairs 

Note: 

• Zone of cell division 

• Zone of elongation 

• Zone of maturation 

*In this lab we used a germinated corn (Zea mays) 

Water Transfer to Xylem 

*During this experiment we used Celery to determine if the xylem uptake of water is affected/influenced by a break of air. (Spoiler Alert: it was) 

Exercise: Xylem Function 

In this we used a slide of a celery dyed to look at the xylem 

Upward Movement of Water – Transpiration (lost of water) 

• Majority of water lost is through leaves; however, this also occurs in flowers. 

This experiment we dyed water and cut a small section of the stem off and placed the flower (Carnation - Dianthus) in the dye 

Results: we were able to see the xylem travelling up the leaf/petals* 

Plant-Water Relations 

• Guard cells opening/closing stoma: 

• Opening: Guard cells absorb water (become turgid). In this situation guard cells they expand and bend forming a stomatal pore. 

• Close: Lose turgid and shrink. In this situation the stomatal pore closes. 

• Guard cells regulate gas exchange. No gas exchange can take place when stomatal pore is closed. 

Stomatal Structure 

Guard Cells 

• Eudicot: Bean Shape and attached at the ends. Microfibrils bands are formed in the guard cell which lengthen and bow apart instead of expanding in the middle. 

Exercise 2: Stomatal Structure 

In this lab we used the Crassula plant to see the stomata. 

Part II – Plant Nutrition 

• Growing green plants require: 

• Suitable temperature 

• Carbon Dioxide 

• Oxygen 

• Water 

• Light 

• Cardon, hydrogen, oxygen 

• Macronutrients 

• Micronutrients 

There are thirteen Macronutrients and Micronutrients 

Macronutrients - Nutrients needed in large amounts. This includes: 

• Nitrogen (N) 

• Phosphorus (P) 

• Calcium (Ca) 

• Potassium (K) 

• Magnesium (Mg) 

• Sulfur (S) 

Micronutrients - Nutrients needed in small amounts. This includes: 

• Iron (Fe) 

• Chlorine (Cl) 

• Copper (Cu) 

• Manganese (Mn) 

• Zinc (Zn) 

• Molybdenum (Mo) 

• Boron (B) 

In commercial fertilizers there are three primary nutrients such as nitrogen, phosphorus, and potassium. 

Hoagland Solution - A medium composed of all essential nutrients for healthy growth. 

Table 2. 

Mobile Nutrients - nutrients that can be moved to areas of low priority to areas of high priority. In a situation where the plant is deficient in a mobile substance, older tissues will be observed to have symptoms first, then newer tissue. 

Immobile Nutrients - nutrients that cannot move to high priority (new tissue) and instead stays in older tissue. In this situation, newer tissue will exhibit signs of deficiency first. 

Table 3. Symptoms of Nutrient Deficiency 

Table 4. Functions and Deficiency Symptoms of Some Major Elements