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

Is it alive? - Living things and Protocols (27 June 2012)

1. List the characteristics of living things.

• Can respond to changes (matter of how fast)
• Can die
• Can move on its own
• Ability to reproduce
• Can grow
• Respire
• Evolve
• Made of cells
• Have hereditary information

2. List the conditions needed to support life.

• Air
• Food
• Water

A common mistake is that people think warmth is a condition needed to support life. However, this is not true! A good example is cold-blooded animals. Cold-blooded animals have the ability to adapt to their surrounding temperature and hence, these animals may be inhabiting in a cold environment but can still survive. Moreover, some plants grow better in cold surroundings. It depends on their breed. Hence, it is not right to conclude that warmth is needed to support life.

3. Discuss with your partner how you would carry out experiments to find out whether some unknown pellets or powdered substances are actually living things.

• Which characteristics of the living things are you using in your experiment?

We are using the characteristic "Made of cells".

• How would you carry out the experiment?

We will examine the specimen under a microscope and look out for cells in the specimen. 

• What kind of evidence will you collect to show that it is living?

We will be unable to collect solid evidence but only pictures. We can take pictures through the lens of the microscope to observe and study the contents of the specimen. Alternatively, we can just look through the lens of the microscope and examine the substance, however, we will be unable to produce solid evidence if we do so. 

• From the evidence, can you infer that it is a living thing?

Yes, we can. If we are able to spot cells in the specimen under the microscope, we can conclude that it is a living thing since all living things are made of cells. However, if there is no sign of cells in the substance, we can deduce that the specimen is non-living.

Experimental methods from other groups:

• Using the characteristic "Living things respire", we can fill up a bag with a fixed amount of oxygen, put the substance in and seal the bag tightly. After 30 minutes, use a datalogger to check the amount of oxygen in the bag. If the oxygen amount has reduced, we can conclude that the substance is a living thing.
• Using the same characteristic "Living things respire", we can pour lime water into a transparent bag, put the substance into the bag and then seal the bag tightly. After 10 minutes, if the lime water appears to be chalky, we can deduce that the substance is a living thing because respiration produces carbon dioxide and when lime water absorbs carbon dioxide, it turns chalky.

Get a Grip - Look back at your record of observations of the way other primates use their hands

1. In what ways do primates use their thumb?

Primates mainly use their thumbs to grip onto branches in order to climb trees. Furthermore, they also use their opposable thumbs to pick up things just like humans but mostly fruits and leaves for consumption.

2. How are these ways different from what you just discovered about how humans use their thumbs?

Primates use their thumbs for movement purposes as well while humans only use their legs for mobility.  Apart from this difference, the thumb is mainly used for picking up objects and holding objects for both humans and primates. After all, we humans did evolve from primate in the ancient times. Hence, we have huge similarities as to the use of our body parts and in this case, our thumb.

Get a Grip - In what way do you think the thumb is important to the way humans use their hands?

The thumb is the only opposable digit in a human's hand and at least one opposable finger is needed most of time for a steady grip on an object. Some of the actions that we carry out daily are impossible without out thumb. Examples of such actions are:

• We can't tie our shoelaces.
• We can't hold a pen and hence, cannot write.
• We can't hold a spoon or fork properly to eat.
• We can't hold chopsticks at all.
• We can't type on our phones easily.
• If you were a doctor, you can't perform surgery without your thumb.
• If you were an electrician, you can't fix electrical glitches without your thumb.

Get a Grip - Questions on how primates move

26 June 2012

1. How do primates climb trees?

2. How are the primates' knuckles designed such that it can hold the primate's weight while walking?

3. Do the primates experience pain due to putting their weight on their knuckles while walking?

4. Primates are said to move on 2 legs for short distance. Why don't they move the same way for long distances?

5. How is putting their weight on their knuckles while walking advantageous than putting their palms flat on the ground?

Kindly comment and put your thoughts down about what you think about these questions. You can comment if any of my questions seem to be unclear as well! 

Get a Grip - Observation of how the gorilla moves about using their arms, legs, hands, and feet.

Observation of how the gorilla moves about using their arms, legs, hands, and feet

26 June 2012

1. Gorillas put their weight on the back of their flexed fingers while walking rather than placing their palm flat on the ground to support their weight.

2. Gorillas have long arms and hence, making them almost upright when they walk with their weight resting on their knuckles. As a result of this, there will be no pressure on their arms and only on their knuckles. 

3. Gorillas put their feet flat on the ground while "kunckle-walking".

References:

http://www.enchantedlearning.com/subjects/apes/gorilla/

http://www.letus.org/bmatters/animals/gorilla.html

http://books.google.com.sg/books?id=wSXgVKUYpvgC&pg=PA12&lpg=PA12&dq=how+do+gorillas+use+their+feet+to+move&source=bl&ots=NXP9SNPcTK&sig=aB6kWBSusopHv8N54-WwqtJ1usw&hl=en&sa=X&ei=GanvT42dN4XKrAf3svW9DQ&ved=0CF0Q6AEwAQ#v=onepage&q=how%20do%20gorillas%20use%20their%20feet%20to%20move&f=false

Photo taken from: http://www.animalcorner.co.uk/wildlife/gorillas/graphics/gorillawest.jpg

Get a Grip - Observation and Drawing of how I hold my water bottle

This is my drawing of how I hold my water bottle. On the right of the picture is my description of how I am holding the water bottle which reads " 4 fingers on one side of the object, thumb at the other side". 

Get a Grip - List of different ways of holding different objects with one hand

26 June 2012

List of different ways of holding different objects with one hand

1. Gripping with thumb and ndex finger (pinching)

2. Four fingers at one side of the object, thumb at the other side

3. Four fingers curled around the (small, thin, long) object. Thumb curled, in contact wiht other fingers.

4. Palm and four fingers curling around the object

5. Index and middle finger "pinching" ("scissors")

6. Similar to (5), but using ring finger and last finger.

7. Two palms touching the opposite sides of the object 

8. Letting the object rest on one one palm when palm is facing up and the object is placed on top of the palm

9. Index finger and thumb on opposite sides of the object 

10. Index finger and thumb holding the top and bottom of the short object