Biology Investigation

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  • Topic: Sunflower, Fruit, Plant
  • Pages : 5 (1206 words )
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  • Published : March 21, 2013
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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 sunflower seed
* Dependant variable: direction of growth of sunflower seed shoot and root * Constant variables: the test tube in which the seeds are kept, the place the test tube rack sits, the orientation of each seed

 
Phototropism
* Independent variable: orientation of sunflower seed, place of light source * Dependant variable: direction of growth of sunflower seed shoot and root * Constant variables: the box in which the seeds are kept, the place the box sits, the orientation of each seed, the materials used (filter paper, large test tube, test tube rack)  

 
Experimental Control:
Geotropism
One of the test tubes was set up with a sunflower seed and the shoot facing up, the natural orientation.  
Phototropism
A cardboard box was set up with hole punctures in the top and sides to allow light to get to the plants from all directions.  
 
Method:
Geotropism
* Collect equipment
* Set up 4 large test tubes in a test tube rack and label them A, B, C and D. * Soak the 4 filter papers under water
* Roll up one filter paper and place in test tube A, along with the sunflower seed shoot facing up to be the control. * Repeat step 4 but with test tube B, with the sunflower seed shoot facing down. * Repeat step 4 but with test tube C, with the sunflower seed shoot facing right. * Repeat step 4 but with test tube D, with the sunflower seed shoot facing left. 1. Place in an area with adequate natural light

2. Water every day for 5 days, taking observations on the direction and length of growth on the seeds.  

 
 
Phototropism
1. Collect equipment
1. Set up 4 large test tubes in a test tube rack
1. Soak the 4 filter papers in water
1. Roll up filter paper and place in test tubes, along with the sunflower seeds with all shoots facing upward. 1. Label 3 cardboard boxes as 1. control, 2. left, 3. right 1. Puncture 10 holes in both sides and...
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