A Bit About Me!

MEMEMEMEMEME!!

I thought i'd write a bit about me, so you can put a personality to blog, so to speak.

So, me....what can I say?

Well, i'm a 17 year old girl from England, I'm currently embarking on my AS levels in sixth form, and my journey to university is underway.

I've trawled through so many university websites, and initially had a list of about 30 i wanted to visit!

I eventually managed to narrow it down but still ended up ordering about 20 prospectuses! From there, i've managed to narrow it down slightly more and am planning to visit a few open days; I went to Hertfordshire university yesterday, but it didn't inspire me all that much, i'm also planning to look at Cardiff, Bristol, Birmingham, Aston, Reading, Leeds, Nottingham, Portsmouth, Exeter, Plymouth and possibly Kent - that's my (quite long) shortlist. Hopefully from that i'll be able to narrow it down to 5!

I'm planning to study psychology or paleontology, it's a tough choice as i've been fascinated with both from such a young age, hopefully i'll be able to make a decision soon though.

Anyway, enough about uni hunting, i've just started trying to write my personal statement (i'm way ahead of schedule, i know) and i need a break from it all, i don't even get my predicted grades for year 12 until next week, let alone year 13!

I suppose the first thing to say is...I love penguins, I mean, who doesn't? Especially emperor penguins - when those fluffy chicks poke their heads out..just...awwwwwwwwwwwwwwww!!!!!

I'm also an Explorer scout, and I love it, we do so much cool stuff, this week, we're getting all DIY and making wood burning stoves out of old coathangers and GIANT baked bean tins, then we'll be cooking on them. :) Other stuff we've done includes: murder mystery, swimming, camps, problem solving, balloon cars, cardbard castles, which was basically a big water fight in the woods - we had to protect ourselves in forts made out of boxes. They say Explorers are just big beavers. :') There's also a summer camp every year, I only joined last june so this will be my first one - so excited! :D



The bridge we built at Explorers once



The view from Thor's cave - on a camp.



I also enjoy reading when I can find the time, and I love swimming, but I am literally THE WORST swimmer in history. Eating is a pretty good hobby of mine too haha :P

Oh, and I got a new camera last summer for the Olympics and my trip to New York last month - I really enjoy photography, here's some of my photos:

 

I'm quite proud of those.

Anyway, I should probably get going, I have a biology ISA next week and it's my last chance, if i can ace this, it'll take some pressure off from the exams in the summer. Plus i want to watch Miranda tonight - SUCH FUN!

If there's anything you guys want me to blog about (i realise revision and my random pictures may get a bit dull), just comment and let me know! :)

There are 10 types of people in the world - those who can read binary and those who can't.

Alons-y! x

Standard Deviation - Biology topic 7.2

Standard Deviation (Topic 7.2)

This is going to be an interesting post due to the lack of caracters available to input to demonstrate the equation. I realise that S.D can be confusing anyway, but I will do my best here! 

 

Standard Deviation Equation




Key to the symbols used in the equation

 

Do not be daunted! It's not as scary as it seems - honest!!

I will demonstrate 2 methods to calculate standard deviation, one in 6 steps, the second in 3 steps. Personally, I use the second method as it takes less time, but it is entirely up to you - the same result is achieved.

METHOD 1

Question: Calculate the standard deviation of the following data: 4, 1, 2, 3, 5, 0

• Calculate the mean []: 4 + 1 + 2 + 3 + 5 + 0 = 15        15 ÷ 6 =2.5

• Subtract mean from measure values [x - ]: 4-2.5,  1-2.5,  2-2.5,  3-2.5,  5-2.5,  0-2.5

                                                                                   1.5       -1.5     -0.5     0.5       2.5      -2.5

• Square all the numbers [ (x - )² ]: 1.5²    -1.5²    -0.5²    0.5²    2.5²    -2.5²

                                                                    2.25   -2.25   -0.25    0.25   6.25   -6.25

• Add all squared numbers together [ ∑(x - )² ]: 2.25+2.25+0.25+0.25+6.25+6.25 = 17.5

Remember to cancel out all "-" and replace with "+" numbers - I find this confusing which is why I opt for Method 2.

• 
  Divide answer by the total number of measurements minus one [ ∑(x - )² / n-1 ]:  17.5  5 = 2.917

• Square root ∑(x - )²     measurements minus one: √ 17.5  5 = 1.87

METHOD 2

Question: Calculate the standard deviation of the following data: 4, 1, 2, 3, 5, 0

• Calculate mean []: 4 + 1 + 2 + 3 + 5 + 0 = 15        15 ÷ 6 =2.5
• Subtract mean from measure values [x - ]: 4-2.5,  1-2.5,  2-2.5,  3-2.5,  5-2.5,  0-2.5

                                                                                   1.5       -1.5     -0.5     0.5       2.5      -2.5

• Square root&divide by number of measurements minus 1:

                                                                                              

GOOD LUCK!! :)

AQA Biology - Topic 13.8 - Movement of water up stems

Firstly - apologies that these blogs will not be in order, I realise that this may be confusing if you are looking for a particular topic, I am just posting in the order that I am using for myself.

MOVEMENT OF WATER UP STEMS

The main force that pulls water up the stem of a plant is evaporation of water from leaves - TRANSPIRATION.

Movement Of Water Out Through Stomata

• Humidity of atmosphere is usually less than that of air spaces next to stomata.
• When stomata are open, water vapour molecules diffuse out of air spaces into surrounding air.
• Changing the size of stomatal pores means plants can control their rate of transpiration.

 

Movement Of Water Across The Cells Of A Leaf

• Water is lost from mesophyll cells by evaporation from their surfaces to the air spaces.
• This is replaced by water from xylem by apoplastic or symplastic pathways.
• In symplastic pathway, water movement occurs because:

         -Mesophyll cells lose water to air spaces.

         -These cells now have lower water potential so water enters by osmosis from neighbouring cells

         -This loss of water lowers those cells water potential.

         - In turn, they take water from neighbours by osmosis.

A water potential gradient is established that pulls water from the xylem, across the mesophyll and into the atmosphere.

Movement of water up the stem in the xylem

The two main factors responsible for the movement of water up xylem, from roots to leaves, are cohesion-tension and root pressure.

Root pressure is explained in topic 13.7.

The cohesion-tension throry:

-Water evaporates from leaves as a result of transpiration.

-Water molecules form hydrogen bonds between one another (cohesion)

-Water forms a continuous, unbroken pathway across mesophyll cells and down xylem.

-As water evaporates from mesophyll cells to air spaces beneath stomata, more molecules of water are drawn up behind it as a result of this cohesion. (Imagine sucking water up a straw!!)

-Water pulled up xylem as a result of transpiration pull.

-Transpiration pull puts xylem under tension - there is negative pressure within the xylem.

Transpiration pull can raise water 100m or more up trees.

Evidence for cohesion-tension theory:

• Diameter of tree trunks change according to the rate of transpiration. During the day (transpiration greatest), there is more tension (more negative pressure) in the xylem - this causes the trunk to shrink in diameter.
• At night (transpiration lowest), less tension in xylem - trunk diameter increases.
• If a xylem vessel breaks and air enters, the tree can't draw up water as the continuous column of water is broken so molecules no lobger stick together.
• When a xylem vessel is broken, water doesn't leak out as it would if it were under pressure, instead, air is drawn in - consistent with it being under tension.

-Transpiration pull is passive so does not require energy for it to take place.

-The xylem vessels through which water passes are dead so cannot actively move water.

-As they are dead, their end walls can break down, meaning xylem forms a series of continuos, unbroken tubes from roots to leaves, which is essental to the cohesion-tension theory.

-Energy is nevertheless needed to drive transpiration - this energy comes from the sun.

Any questions - just ask! :)