Exercise 13Respiration

I. Introduction

Plants can take in energy through the process of photosynthesis and store this energy in molecules of carbohydrates. This energy will used by the cell to carry out its biological processes. Energy is made available through the process of cellular respiration. Cellular respiration, which occurs in the mitochondria, is the breaking down of food molecules to release energy in the form of ATP. It requires sugars and oxygen while it produces carbon dioxide, water and energy. Respiration consists of three phases called Glycolysis, Citric Acid Cycle and Oxidative Phosphorylation.

In this experiment, we observed the use of oxygen, the production of heat energy and carbon dioxide using germinating seeds and indicators such as phenol red and bromthymol blue.

Hypothesis

Amount of oxygen, temperature and amount of carbon dioxide are important factors that can affect cellular respiration.

Objectives 1. To observe, prove and understand how oxygen is used up by the plant during respiration2. To determine the cause of heat production in germinating seeds3. To observe, prove and understand how carbon dioxide is produced during respiration

II. Results

Table 1: Use of OxygenSet-up Description Result

A Germinating mungbean seeds

The phenol red changed into a lighter, yellowish color (results not so evident due to short experimentation period)

Occurrence of a precipitate

Cotton turned into red Became moist

B Killed Seeds No changes occured

Table 2: Production of Heat EnergySet Up Description Temperature

Start 30 min 1 hourA Germinating

Seeds28° 29° 29.5°

B Dry Seeds 29° 30° 30°

Table 3: Production of Carbon DioxideSet-up Description Result

A Soaked seeds Bromthymol blue turned into a lighter color

III. Discussion

A. Use of Oxygen The change in color

Germinating seeds used oxygen and underwent respiration thus producing carbon dioxide. Carbon dioxide mixed with water forming carbonic acid. The change in color of the phenol red to lighter yellowish color indicated an acidic solution.

Occurrence of precipitate Potassium hydroxide absorbed the carbon dioxide released producing

K2CO3 which is the precipitate.

Cotton turned into red Cotton turned into red indicated the transport of water from the other

container to the container with seeds. Since potassium hydroxide absorbed carbon dioxide, the use of oxygen by the seeds led to a decrease of gas volume and for the water in the other container to move to the container with seeds.

B. Production of Heat Energy Increase in temperature in set-up with Germinating seeds

The increase in the temperature indicated the occurrence of cellular respiration in the Germinating seeds. During respiration, ATP is produced in the form of heat energy.

C. Production of Carbon Dioxide Change in color of Bromthymol blue

Seeds underwent respiration producing carbon dioxide which was indicated by the change of color of the Bromthymol blue (turned yello-green). Carbon dioxide reacted with water turning into carbonic acid

which led to the acidity of the solution causing the Bromthymol blue (a pH indicator) to change color.

Respiration is the process that breaks down compounds to produce energy in the form of ATP. It uses oxygen and glucose to produce carbon dioxide, water and energy. Respiration in plants is affected by several factors like the amount of oxygen, carbon dioxide and temperature. There are two types of respiration namely, aerobic and anaerobic. Aerobic respiration requires the presence of oxygen while anaerobic respiration does not. Examples of cells undergoing aerobic respiration are plant and animal cells and examples of cells undergoing anaerobic respiration are muscle cells and yeast.

IV. References

Miller, K.R. and Levine, J.S. 2006. Biology. Prentice Hall. boyles.sdsmt.eduwww. carolina.comanswers.yahoo.comhttp://www.tutorvista.com/content/biology/