In the last classes of Biology, we have been studying Evolution and Natural and Human selection. We were asked to make a 5-line (approx.) summary of it.
Evolution is any change in the heritable traits within a population across generations. Traits are the little things that are specified in our DNA. For example, the color of the eyes, length of the fingers, amount of hair in the body, etc.
Descent with modification is the fact that when parents have children, those children will look and behave a little bit different from them. These changes happen because of random variation in the DNA of he offspring.
Natural selection is something that the nature does to make organisms take advantage of evolution. For example, if ‘nature’ doesn’t want frogs to be eaten by snakes, then a frog would be born with a frightening color. That way, when it reproduces, frogs with that color will not be eaten and the rest will die. This way frogs can keep existing.
When cells reproduce they divide themselves in two, and the two new cells grow back to the normal size. When they duplicate their nuclei is also duplicated, so the DNA is the same in both. But sometimes this might fail and the DNA may have changed. This is called DNA Mutation. This is another form of evolution.
When we reproduce the genes contatined in the DNA and traits of the mother and the father will mix, creating a new set of DNA. This will be passed on the his/her children and DNA will keep changing. This is Evolution.
Describe what we did last class (Wednesday) and the results today
You may add drawings or photos to be clearer
Last class we preapered flavourless jelly without cooling it to make it solid. Then, we decided that we wanted to watch bacteria reproduction, and as flavourless jelly is transparent and of an interesting solidity it was a nice thing to test it on.
To do this we had to choose between coughing on our hands, or touching dirty things such as the floor. We chose to cough and then we put our finger on the non-solid-yet jelly. All this we did on a petri dish which are used to grow bacteria.
Today, after 1 week we went to the lab to see the result of our bacteria growth. Our dish isn’t so dirty, so we can guess that one week ago our mouth was quite clean from bacteria. Instead, the people that chose to touch the floor got more disgusting results. Here is ours:
On July the 5th, we prepared a flask with soaked lentils, cotton and blotting paper to make the seeds germinate. In my case, as I didn’t had a flask that day, I started the project by myself on Mar Del Sur the 22nd of July.
We worked in pairs, in my case, with Lucas Alonso Breuer studying variables (temperature, water, sunlight and oxygen).
The variable we studied was with sunlight, so Lucas protected his flask from sunlight, but he made a mistake and give it artificial light, which we later found out that also helps for photosynthesis. Also we couldn’t compare perfectly our results as I by mistake put in another temperature than him, more info below (;.
Besides of starting a couple of weeks later, I actually had more difficulties than that one. In MDS, the temperature was very cold, which I did most definitely not expect, so I didn’t know when to water it or were to leave it. After fighting for 3 days with the seeds, the 4th day they germinated.Pitifully, they died on day 7 because of the cold (I suppose). After seeing this, I accidentally dropped the flask and couldn’t take a proper picture
Reproduction is one of the fundamental characteristics of all living things. Each kind of organism, has a certain way to reproduce but all of the methods are divided in sexual reproduction and asexual reproduction. In reproduction, each organism gets a set of chromosomes from their parents. Chromosomes are a set of DNA which is in contained in the nucleus, and contains a set of instructions called genes.
Just one parent
A cell divides and creates two new cells
As it is one parent, the genes keep the same, producing the new cells to look exactly the same to their parents
Example: Potato reproduction
Potatoes reproduce by using stem tubers. Some tubers grow above the surface and grow leaves, which photosynthesizes. Others, grow underground, and swelling form on them. This swellings are provided with sucrose which comes from the leaves. Then, the sucrose is converted to starch and stored, creating potatoes. This is why they are a great source of starch. Also, each plant can produce many stem tubers.
In sexual reproduction, the parents organisms produce sex cells called gametes, an example of this are sperm (male gamete) and eggs (female gamete). When this two gametes join and their nuclei fuse, it is called fertilisation. When this happens, a new cell is created, called zygote. The zygote divides repeatedly and ends up creating an organism which has chromosomes and genes from both parents.
Gametes are not like every cell. Gametes contain only half as many chromosomes as normal cells, so when gametes fuse, the zygote will have the normal amount of chromosomes (46)