The new topic in Biology is the Endocrine System and we were to do the activities on Male’s blog:

1. Hormone: chemical substance produced by a gland, carried by the blood, which alters the activity of one or more specific target organs.
2. Search in the internet a picture which shows the glands which secrete  hormones in the human body.

What hormones secrete each gland:

Adrenal gland: Adrenaline
Pancreas: Insuline
Testis: Testosterone
Ovary: Oestrogen
Thymus: Thymosin
Thyroid gland: Thyroxine and calcitonin
Pituitary gland: Growth hormone
Pineal gland: Melatonin

3. ADRENALINE. State the effects of adrenaline. Chose a picture which shows a situation in which adrenaline is secreted. Explain.

Adrenaline is when you are frightened, excited or keyed up. There your brain sends impulses along a nerve to your adrenal glands, and these secrete adrenaline into the blood. The main effects of adrenaline are: Your hearts beats faster, your breathing rate increases, your pain body’s ability decreases and it causes a noticeable increase in strength and performance.

Today we went to the lab and did an experiment on extracting DNA. This is how it got carried out:

Aim: 
To extract DNA from natural products

to observe the fibrilar structure of DNA.

Materials
Plastic cups – onion, banana

test tubes – Distilled water

knife – detergent

sticks – salt

a beater – ethanol

Method
1- Cut the central part of the onion into cubes.

2- Add 3 tsp of detergent and 1 of salt in a plastic cup, and pour distilled water up to the top.

3- Mix this solution with the pieces of onion.

4- Beat all the mixture at high speed for 30 seconds.

5- Filtrate the liquid with a coffee filter.

6- Fill ¼ of a test tube with the filtrate.

7- Add some pieces of banana and mix thoroughly.

8- Add the same volume of ethanol, carefully, so that it flows through the walls of the test tube and forms a layer on the filtrate.

9- Let it rest for 2-3 minutes until a cloudy area is formed between the 2 layers.

10- Extract a network of white fibres of DNA and place it on a Petri dish.

11- Add few drops of blue methylene and record your observations.

Results
Record your observations!

Discussion
a- Where in the cell is the DNA?
The DNA is in the nucleus.

b- What are the fibres made of?
The fibres are nucleotides joined together.

c- What is a gene?
A gene is a length of DNA that codes for a protein.

Conclusion
What is the DNA?
DNA is deoxyribose neuceic acid.

Male, our Biology teacher divided the class into groups and assigned different drugs to do presentations on to each of them. I worked with Catu, Flor, Delfi and Pancho. We had to present tobacco. Here’s the poster we made:

Click here for larger version

In Biology, we’re learning about the eye as a sense organ. Male, our teacher prepared a blog post with some questions for us to work on.

We had to look up a video on pupil reflex:

And then we had to make a flow chart on the pupil reflex:

Effect: circular contracts, radial relaxes.

Response: Pupil constricts

Effect: Circular relaxes, radial contracts.

Response: Pupil dilates

In Biology we started learning about new topic: the nervous system. We had to watch a video, take down notes and do some activities on Male’s blog.

1. a.  -The control centre.

– The receptors.

– The neurones.

– Central nervous system.

– The nervous system.

b.   Motor Neuron: Carries signals from the CNS to the effectors. 

Sensory Neuron: Carries signals from receptors to the CNS. 

Relay Neuron: Carries messages from one part of the CNS to another.

Neuron Synapse: a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.

Video of neuron synapse:

https://youtu.be/WhowH0kb7n0