A sneak peek into the reason behind peristalsis...

There are two types of muscles in the esophagus.

During peristalsis, one of the muscles will contract and the other will relax.

• ·      Circular muscles (vertical muscles)
• ·      Smooth muscles (horizontal muscles)

    

    When the circular muscles contract, it becomes shorter.

    

    When the smooth muscles contract, they make the opening of the esophagus smaller. (smaller diameter of the esophagus). 

Introduction to diffusion

Based on a video that we watched in class...

Is diffusion a spontaneous process? (no energy required)

Yes, energy is not required for diffusion to take place.

Why does diffusion not occur instantaneously in the living world?

Diffusion occurs instantaneously in vacuum. However, there is barely any places with vacuum in the living world, except in experimental set-ups.


What are the factors affecting rate of diffusion?

• The size of the particles
• The temperature of the fluid in which the particles are in

Mealworm Experiment - Biology Lab Report (22 July 2012)

Variable: Sound

Aim: The aim of the experiment is to find out whether high-pitched or low-pitched sound affects the mealworms’ movement.

Hypothesis: The mealworms behave differently when exposed to high-pitched sounds.

Independent variable: the pitch of the sound that the mealworms are exposed to.

Controlled variables: Temperature of the surroundings, noise level in the background, the presence of wind, the amount of light the mealworms are exposed to and the distance between the sources of the sound and the mealworms.

Dependent variable: Speed and direction in which the mealworms move

Assumptions made: None of the mealworms are hearing impaired and all of them have the same sensitivity to the sounds produced.

Materials/Apparatus:

• 2 mealworms [ One in its early larval stage: Mealworm A, One in its late larval stage: Mealworm B ]

• Castanet

• Tambourine

• Rubber bung

Procedure: 

Step 1: Hold the castanet 3 cm away from the top of the open box, containing the mealworms.

Step 2: Make sounds with the castanet for 1 minute and observe the mealworms while the sound is produced and subsequently observe the mealworms for the next 30 seconds after the sound has been stopped.

Step 3: Write down observations. 

Step 4: Repeat Steps 1, 2 and 3 with a tambourine and rubber bung.

Results: 

	Mealworm A	Mealworm B
Rubber Bung	Moves very slowly throughout and does not go in any particular direction	Moves at a fast paces and goes in a circular motion around the box
Castanet	Moves very slowly throughout and does not go in any particular direction	Moves at a fast paces and goes in a circular motion around the box
Tambourine	Moves very slowly throughout and does not go in any particular direction	After 45 seconds, the mealworm lifted its head up towards the sound source until the sound stopped.
Tambourine & Castanet	Moves very slowly throughout and does not go in any particular direction	Stopped moving after 40 seconds and remained like that until it was stimulated with touch

Data analysis:


Mealworm A probably did not react to any of the sounds because it had not developed its sense of hearing yet. As for Mealworm B, it did not react to the sounds made by the rubber bung and the castanet probably because these were low-pitched sounds. However, it behaved differently when exposed to the sound of the tambourine alone and the tambourine and castanet together. Since the tambourine produces a high-pitched sound, perhaps the mealworm only reacted to the sounds with elements of high pitch.


Conclusion:


Mealworms' movement is affected when exposed to high-pitched sounds.

Home-based learning and HVP There's A New Frog In Town

13 July 2012

Home-based learning and HVP Silence of the Bees

2 July 2012

Is it alive? - Why were water, glucose and salt water chosen for the experiment? (27 June 2012)

Water is chosen because...

Living things need water to survive. Hence, when the substances are put in the water and there is a decrease in the amount of water, it can be concluded that the substance is a living thing. However, if there is no change in the water volume, we can deduce that the substance is a non-living thing.

Glucose is chosen because...

Glucose is food. Living things need food to survive. Hence, if there is a decrease in the amount of glucose in the test tube after the substance is put in, we can conclude that the substance has taken in the glucose for survival, resulting in a conclusion that the substance is a living thing.

Salt water is chosen because...

Salt is generally needed for most living things to digest food and produce energy. Therefore, if there is a  decrease in the salt amount in the water after the substance is put in, we can deduce that the substance is a living thing.

Is it alive? - Experiment Part 1 Observations Table (27 June 2012)

Substances are each put in a test tube of 3ml of water. My lab partner and I have not come up with our inference for each of the substance. We will update the table soon! Look out for the results (:

Substance	Physical Appearance	Initial observation	Changes observed after 10 minutes	Inference/ Evidence of life
A	Flaky and brown in colour	Sinks, does not dissolve	Most of the grains have sunk
B	Very small grains and light brown in colour	Fully dissolves	The grains dissolve in the water but a few grains sediment at the bottom.
C	Tiny marble-like colourless grains	Sinks	Particles are suspended and the grains have become bigger.
D	Small sphere-like  grains, dark brown in colour	Some float on the surface, the rest sink	Water is clear. The particles have sunk.
E	Very fine grains and dark brown in colour	Some float on the surface, a few are suspended, the rest sink	Water is cloudy. Particles: Few are suspended, half is sunk, half is floating on surface