ISS Literature Review (Dylan)

Geotropism (also called gravitropism) is the directional growth of an organism in response to gravity. Roots display positive geotropism when they grow downward, while shoots display negative geotropism when they grow upward. 

Perception is the sensing of environmental stimuli. Perception allows organisms to gain information about properties and elements of the environment that are critical to their survival. 

Gravity sensing cells at the end of the roots called statocytes let the plant know the direction of gravity. The process is known as Gravitropism. Roots show a positive response to gravity as they grow downward, whereas the stems show the opposite response. 

• If a plant shoot display negative gravitropism and when it is placed on its side, a plant shoot will grow up
• If a plan root display positive gravitropism, they will grow down.

Gravity plays a role in the concentration of Auxin, a plant growth hormones, in the root celsl. Changes in the auxin concentration allow throughout the root allow its cells to divide and bend with gravity.

Bibligraphy
Maria (d.u.) How do roots grown when direction of gravity changes? Retrieved July 10 from http://www.indiastudychannel.com/projects/250-How-Do-Roots-Grow-When-Direction-Gravity-Changes.aspx

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/Auxin.html

ISS Literature Review [Ikmal]

Question: How do roots grow when the direction of gravity changes?

Hypotheses: The roots would grow towards the ground.

Introduction

Plants respond to earth’s gravitational attraction, and also to light. Stems grow upward towards light. Roots grow downward and away from light. These responses are called tropisms. Plants’ growth in response to gravity is known as gravitropism; the growth response to light is phototropism. Both tropisms are controlled by plant growth hormones.

Gravitropism is a plant's growth response to gravity. This occurs because of the plant hormone also called auxin that plays a part in gravitropism. When the plant is laid on its side, the auxin concentration increases along the lower sides of the roots and stems of the plant. The auxin stimulates cell elongation on the stem which makes the stem bend up toward the sky. The auxin prohibits cell elongation in the roots which causes the roots to bend down into the soil. Gravitropism allows the plant to respond to gravity no matter what position the plant is in.

Bibliography

http://www.bioedonline.org/lessons-and-more/lessons-by-topic/plants-form-function/how-does-gravity-affect-root-growth/ Retrieved on 9 July 2013

http://herbarium.desu.edu/pfk/page8/page9/page9.html Retrieved on 9 July, 2013 Biology of Plants, 6th ed. Raven, Peter H., Everert, Ray F., Eichhorn, Susan E. Worth Publishing 1999. 

Botany: An Introduction to Plant Biology. Mauseth, James D. Jones and Bartlett Publishers. Sudbury, Massachusetts 1998.

ISS Literature Review (Tzun Kai)

Literature Review

Done by: Yeo Tzun Kai

Research Question:

 How do roots grow when the direction of gravity changes?

Hypothesis
The roots will grow towards the direction of gravity.

Introduction

Geotropism describes how plants respond to gravity. Roots are termed positively geotropic as they grow toward the direction of the pull of gravity. Shoots are negatively geotropic because they grow away from which also can be said as opposite the gravitational pull. If you plant a seed on its side, the shoot and root will emerge horizontally, but will quickly change their direction of growth. Within hours of germination, the shoot will bend to grow upward and the root will bend to grow downward.

Auxin was initially used to describe what were thought to be a group of chemicals responsible for promoting growth in response to stimuli. Therefore, under the influences of gravity, the Auxin migrates to the lower side of the stem. Here, the hormone stimulates growth, causing the lower side to grow more quickly than the upper, bending the stem upwards while the opposite happens to the roots. This is because in the stem, the Auxin collects in the lower side of a horizontal root. However, root cells behave differently than stem cells. Root cells elongate in response to the lower levels of Auxin in the upper surface, causing the roots to bend downward.

Bibliography 

National Gardening Association (published in 1999) Response to light Retrieved 9 July 2013, from http://assoc.garden.org/courseweb/course1/week2/page14.htm

National Gardening Association (published in 1999) Response to gravity Retrieved 9 July 2013, from 

http://assoc.garden.org/courseweb/course1/week2/page15.htm

ISS Literature Review (Douglas)

Abstract

An investigation of how roots grow when the direction of gravity changes.

Hypothesis

Roots will grow according to how the gravity direction chenges.

Introduction

A process called geotropism (also called gravitropism) is the response of plant roots to gravity. There are two types of geotropism: positive geotropism and negative geotropism. Positive geotropism is observed in plants when their roots grow downward, while on the contrary, when shoots grow, negative geotropism is observed. Many different explanations have been proposed for why plant shoots grow “up” and roots grow “down.” Other plant parts, such as root hairs and leaves, may exhibit transversal gravitropism, growing perpendicular to the main up-down axis of the plant. To this day, we know that plants growing on earth have evolved to respond to many different stimulations to help them orient themselves to their best advantage. As you can discover in the phototropism activity, light is a crucial factor in determining the direction of plant growth. But gravity, the force that causes bodies to fall to the earth and holds the planets in their orbits about the sun, is also critically important. The effect of light on plant growth is called phototropism. Phototropism is understood as a secondary process, usually in the same direction as the negative geotropism. Transversal geotropismis is a direction of growth that is vertical to the shoot axis. The direction of many lateral shoots, side roots, leaves, etc. is described by this term. All directions diverting from that of the shoot axis are called plagiotropic. Orthotropic organs (shoot axis, main root) are usually of radial symmetry, plagiotropic organs (leaves, side roots, etc.) are mostly of dorsiventral organisation (having different dorsal and ventral surfaces).

Bibliography:

http://www.nasa.gov/pdf/562190main_LS4_Gravitropism_C4.pdf Retreived on 9 July 2013, (Web PDF file, from National Aeronautics and Space Administration (NASA), Aerospace Education Services Project.

http://www.biologie.uni-hamburg.de/b-online/e32/32c.htm Retrieved on 9 July 2013, (Web) 1996-2004, from University of Hamburg, Faculty of Mathematics, Computer Science and Natural Sciences

Confirmed Project Title

How do roots grow when direction of gravity changes?

http://www.sciencebuddies.org/science-fair-projects/project_ideas/PlantBio_p034.shtml#summary

Hypothesis for 3 suggested project titles

1. An investigation on whether soil will affect the pH of the water

Hypothesis: The soil will affect the pH of the water

2.An investigation of how dissolved oxygen changes in water samples at different temperatures

Hypothesis: The higher the temperature, the lower amount of dissolved oxygen

3. An investigation on how roots roots grow when the direction of gravity changes

Hypothesis: The roots will follow the direction of gravity change

Research Questions and Variables

Project 1: 

An investigation on whether soil will affect the pH of the water

Link to Project:
http://www.sciencebuddies.org/science-fair-projects/project_ideas/EnvSci_p013.shtml

Project 2:

An investigation of how dissolved oxygen changes in water samples at different temperatures

Link to project: 

http://www.sciencebuddies.org/science-fair-projects/project_ideas/EnvSci_p014.shtml#procedure

Project 3:

An investigation on how roots roots grow when the direction of gravity changes

Link to project: 

http://www.sciencebuddies.org/science-fair-projects/project_ideas/PlantBio_p034.shtml#summary

Project Ideas

Project Title 1:
To investigate on how soil affects the pH of water.

http://www.sciencebuddies.org/science-fair-projects/project_ideas/EnvSci_p013.shtml


Project Title 2:
An investigation on how roots roots grow when the direction of gravity changes

http://www.sciencebuddies.org/science-fair-projects/project_ideas/PlantBio_p034.shtml#summary

Project Title 3:
An investigation of how dissolved oxygen changes in water samples at different temperatures.

http://www.sciencebuddies.org/science-fair-projects/project_ideas/EnvSci_p014.shtml#procedure

What is Scientific Method?

The scientific method is a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. Scientific researchers propose hypotheses as explanations of phenomena, and design experimental studies to test these hypotheses via predictions which can be derived from them. These steps must be repeatable, to guard against mistake or confusion in any particular experimenter.