The Effects of Light and Gravity on the Growth of Sunflower Seeds
Biology Investigation
Aim: to investigate the effects of light and gravity on the growth of sunflower seeds. Background Info:
Tropism is directional movement in response to a directional stimulus eg light or gravity.
Plants are not able to relocate if they happen to start growing where conditions are nor perfect but they can alter their growth towards more favorable conditions.
Plants respond to light (phototropism) where the stems grow towards the light and the roots grow away from the light.
They also respond to gravity (geotropism) where the stems grow away from the ground and the roots grow towards the ground.
Tropisms are controlled by auxins - a family of hormones that promote (and sometimes inhibit) growth.
Sunflower seeds need regular watering in order to provide sufficient nutrients and ensure healthy and efficient growth.
Hypothesis:
I hypothesise that whatever orientation the seed is placed in, the shoot will always be positively phototropic and the root will always be positively geotropic, due to the basic laws of tropism. Risk Assessment: Hazard | Risk | Precautions/Disposal | Test tube breakage | Glass may cause injury to eyes or skin. | Be cautious when handling test tube; wear safety equipment such as safety glasses and gloves.Place in glass bin. | Puncturing boxes with scissors | Scissors may injure someone if there is an accident. | Assign somebody to hold the box steadily while they are being punctured. | Using forceps | May injure skin. | Hold forceps steady and try to avoid contact with skin. | Equipment:
Geotropism
* 4x large test tube * 4x filter paper * 4x sunflower seed * 1x test tube rack Phototropism * 1x cardboard box * 4x sunflower seed * 1x pair of scissors * 1x forceps * 4x test tube * 4x filter paper * 1x test tube rack Variables:
Geotropism
* Independent variable: orientation of
Aim: to investigate the effects of light and gravity on the growth of sunflower seeds. Background Info:
Tropism is directional movement in response to a directional stimulus eg light or gravity.
Plants are not able to relocate if they happen to start growing where conditions are nor perfect but they can alter their growth towards more favorable conditions.
Plants respond to light (phototropism) where the stems grow towards the light and the roots grow away from the light.
They also respond to gravity (geotropism) where the stems grow away from the ground and the roots grow towards the ground.
Tropisms are controlled by auxins - a family of hormones that promote (and sometimes inhibit) growth.
Sunflower seeds need regular watering in order to provide sufficient nutrients and ensure healthy and efficient growth.
Hypothesis:
I hypothesise that whatever orientation the seed is placed in, the shoot will always be positively phototropic and the root will always be positively geotropic, due to the basic laws of tropism. Risk Assessment: Hazard | Risk | Precautions/Disposal | Test tube breakage | Glass may cause injury to eyes or skin. | Be cautious when handling test tube; wear safety equipment such as safety glasses and gloves.Place in glass bin. | Puncturing boxes with scissors | Scissors may injure someone if there is an accident. | Assign somebody to hold the box steadily while they are being punctured. | Using forceps | May injure skin. | Hold forceps steady and try to avoid contact with skin. | Equipment:
Geotropism
* 4x large test tube * 4x filter paper * 4x sunflower seed * 1x test tube rack Phototropism * 1x cardboard box * 4x sunflower seed * 1x pair of scissors * 1x forceps * 4x test tube * 4x filter paper * 1x test tube rack Variables:
Geotropism
* Independent variable: orientation of
Bibliography: Kimball, J W 2011, Tropisms, viewed 27 November, 2012, <http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Tropisms.html >. Unknown, 2001, Plant Hormones, viewed 27 November, 2012, <http://www.biology-online.org/3/5_plant_hormones.htm> >.