Category Archives: Biology

Endocrine System

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.

Extracting DNA

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

To extract DNA from natural products

to observe the fibrilar structure of DNA.

Plastic cups – onion, banana

test tubes – Distilled water

knife – detergent

sticks – salt

a beater – ethanol

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.

Record your observations!

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.

What is the DNA?
DNA is deoxyribose neuceic acid.

The eye as a sense organ

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

Nervous System

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: