bio - cambridge y10

photosynthesis (word) equation

carbon dioxide + water → glucose + oxygen with the presence of light and chlorophyll

photosynthesis (symbol) equation

6CO2 + 6H2O →C6H12O6 + 6O2 with the presence of light and chlorophyll

process of photosynthesis

during photosynthesis, light energy is absorbed by a green pigment called chlorophyll, which is found in chloroplasts in some plant cells. this energy is used to convert carbon dioxide and water into sugar (glucose). oxygen is released as a by-product.

testing for starch

1.) place a leaf into boiling water for about a minute
2.) turn off the bunsen burner
3.) put the leaf into a boiling tube containing ethanol. then put the boiling tube into the hot water. the ethanol will boil. leave the tube for about five minutes
4.) remove the leaf from the ethanol and wash it in the water
5.) carefully spread the leaf out onto a white tile or petri dish then cover the leaf in brown iodine solution

why does the leaf have to be placed in boiling water

soften the leaf
stop all chemical reactions

why does the leaf have to be placed in ethanol

breaks down the cell wall
gets rid of chloroplast (the colour) - this will allow the colour change to be more clear

removing the leaf from the ethanol and washing it

gets rid of excess ethanol
softens leaf

covering the leaf in iodine solution

tests for starch

why can we use a starch test as evidence that photosynthesis has been happening?

starch is used as storage when the sun sets and the plants cannot get any light

if starch is present

what colour will the iodine change to?

why is a green area in a plant green?

this presents that there is chlorophyll

why are there white areas of a plant?

this presents that there is no chlorophyll

function of wax cuticle

prevents water from evaporating in the cell

upper epidermis

allows light to enter into the palisade mesophyll
thin and transparent

palisade mesophyll

chloroplasts absorb light for photosynthesis

spongy mesophyll

contains air spaces thereby increasing the surface area to volume ratio for diffusion of gases (mainly CO2)

lower epidermis

contains guard cells and stomata

guard cells

opens and closes the stomata allowing CO2 to diffuse in and O2 to diffuse out

stomata

location of gas exchange
where evaporation of water takes places
often found in greater concentration on the lower epidermis to reduce water loss

vascular bundle

contains xylem and phloem
transports substances to and from the leaf

xylem

supports the plant
transports water and minerals from the mesophyll cells for photosynthesis

phloem

transports sucrose and amino acids around the plant

nitrogen

nitrate

magnesium

magnesium

how would you recgonise a plant's deficient in nitrogen

the plant is no longer growing

how would you recgonise a plant's deficient in magnesium?

colour of the leaf starts turning yellow instead of remaining green

what do plants need in order to carry out photosynthesis

carbon dioxide

what is a variegated leaf

a leaf with different colours

two ways plants are important to humans

absorb CO2 which in turn releases oxygen
turns light to chemical energy which helps the food chain

root hair cells

root hair cells are adapted to absorb water and mineral ions from the soil. for hair cells contain no chloroplast

what process causes water to enter the root hair cell from the soil water

osmosis

what process causes mineral ions to enter the root hair cell from the water

active transport

how does the root hair cell help the plant to bring water and mineral ions into the plant

maximises the surface area exposed

which part of the vascular bundle transports water up the stem

xylem

which part of the vascular bundle dissolves sugar and amino acids up the stem

phloem

transpiration

after water has entered the root hair cell and passed across the root cortex into the xylem vessels

factors affecting transpiration

temperature: temperature affects transpiration as an increase in the temperature will result in faster evaporation of water from the surface of the mesophyll cells in the leaf

humidity: humidity describes the level or water vapour in the air. if humid air collects around a leaf

translocation

translocation is the movement of manufactured food through the tissues of the phloem. in all plants

what are the tubes that carries water and mineral salts up the stem?

xylem

what are the tubes that dissolve food from the leaves to the rest of the plant?

phloem

where is the xylem and the phloem found in a stem?

vascular bundle
the xylem is internal whereas the phloem is external.

how are root hairs adapted to absorb water?

maximised surface areas

what does a potometer measure?

the rate of water uptake
can be measured by how far the air bubble has moved

translocation in simple words

movement of manufactured food through the tissues

omoeba

a unicellular organism

plasma

yellow liquid mainly composed of water with chemicals dissolved in it

red blood cells (erythrocytes)

red blood cells are produced inside the bone marrow. the function of these cells is to transport oxygen around the body. their (biconcave) shape helps with this function. firstly

oxyhaemoglobin (word) equation

oxygen + haemoglobin ⇆ oxyhaemoglobin

the '⇆' is a reversible sign

oxyhaemoglobin (symbol) equation

Hb(O2)4

what part of the body does oxyhaemoglobin form in?

the lungs - they get a lot of oxygen

which parts of the body breaks down oxyhaemoglobin to release oxygen

all cells - all parts of the body

white blood cells (leucocytes)

contains a nucleus (of which could be possibly large). white blood cells are also produced in the bone marrow. there are two types of white blood cells

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lymphocytes and phagocytes.

lymphocytes

lymphocytes are responsible for recognising bacteria and viruses as being 'foreign' and pathogenic. they then make chemicals called antibodies

phagocytes

phagocytes are responsible for engulfing and breaking down/destroying pathogens. these cells move towards the pathogen and engulfs them. phagocytes can leave the blood stream by squeezing through capillaries.

they can be identified by their lobed nuclei. this allows the cells to change shapes for either phagocytosis or to squeeze thorough capillary walls.

platelets (thrombotyes)

platelets are small fragments of cells. their role is in the formation of a blood clot. this is another way that the body fights diseases

haemophilia

haemophilia is a genetic disorder where the body cannot stop bleeding when injured as the bleeding does not clot properly

blood vessels

arteries

arteries

carries oxygenated blood from the heart from the lungs.

the walls of arteries are elastic and stretch to take the blood under high pressure. they then contract and bounce back to force the blood along. this bouncing back can be felt as a pulse as the blood flow through arteries

veins

carries deoxygenated blood to the heart from the rest of the body.

capillaries join up to eventually form veins. veins have a wider lumen and less elastic tissue in their walls. the pressure inside veins is much lower basically preventing the backflow of blood.

capillaries

the arteries branch many times until the smallest branches form capillaries. they are very narrow and taper as they reach the body cells. here. a red blood cell can only just squeeze through. blood flows through the capillaries very slowly

properties of an artery

outer layer

properties of a vein

outer layer

properties of a capillary

thin endothelium

endothelium

endothelial layer

left side of heart

the left side of the heart takes oxygenated blood from the lungs and pumps it the rest of the body

has a much thicker wall than the right side since it needs to generate more pressure so that the blood goes for a longer distance.

left side is more muscular since it has to pump blood that travels to the entire body

right side of heart

the right side of the heart takes deoxygenated blood from the rest of the body and pumps blood to the lungs so that it goes back to the left side of the heart.

muscles in the heart

the more muscular a side of the heart is

vena cava

superior vena cava is the higher one

deoxygenated blood

blood that contains little amounts of oxygen

right atrium

receives deoxygenated blood from the vena cava

right ventricle

receives deoxygenated blood from the right atrium and goes to the pulmonary artery

pulmonary artery

there is one pulmonary artery that splits into two as there are two lungs in the human body

pulmonary veins

there are two pulmonary veins since there are two lungs

supplies the left side of the heart with oxygenated blood from the lungs

left atrium

receives oxygenated blood from the pulmonary veins

left ventricle

receives oxygenated blood from the left atrium

aorta

gets blood from the left ventricle

septum

separates the right and left sides of the heart.

prevents mixing of oxygenated and deoxygenated blood.

double circulation system

helps maintain high pressure in the blood as blood returns from the lungs which in turns allows it to gain more pressure

right side → lungs = pressure lost

lungs → left side → rest of body = pressure regained/generated

renal arteries

renal vein + renal artery \= blood goes to kidneys

what happens to the blood when it goes to the lungs

there is less pressure and the blood picks up oxygen while it drops off CO2

what happens to the composition of the blood change when it gets to the body’s cells, tissues and organs?

the blood picks up CO2 and other chemical waste while dropping O2

heart diseases and vascular problesm

coronary heart disease and thrombosis

coronary heart disease (CAD)

**caused by:** plaque buildup in the wall of the arteries that supplies blood to the heart, thereby causing narrowing or blockage of the coronary arteries

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**common symptoms:** chest pain and breathlessness

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**risk factors:** age, sex (especially men), family history, smoking, high blood pressure, diabetes, obesity, overweight, high cholesterol

thrombosis

basically when there is a blood clot in a blood vessel and the blood clot prevents the blood from flowing normally through the circulatory system.

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**common symptoms:** pain, swelling and tenderness, heavy aching, warm skin in one area, red skin

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**risk factors:** smoking, diabetes, high blood pressure, high cholesterol, lack of activity + obesity, poor diet, family history

reproduction

the production of an offspring

how reproduction can occur

sexual reproduction and asexual reproduction

asexual reproduction

when only one parent is required, there is no fusion of gametes and no mixing of genetic information. the offsprings are genetically clones to the parent and other offsprings, they are identical.

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some plants, a few animals and some simple organisms such as bacteria, amoeba and yeast carry out asexual reproduction.

fragmentation

can occur in (some) starfish.

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the legs of the starfish are all genetically identical and they can grow their legs back from the disk. or, the disk and legs can be grown back from a detached leg.

budding(/binary fission)

occurs in yeast as it reproduces through budding.

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the mother cell grows a protrusion and it will eventually become the same size as the mother cell, then pinches off the mother cell.

binary fission

occurs in amoeba.

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when the individual cell divides into two daughter cells that are genetically identical.

advantages of asexual reproduction

it is a quick process, only one parent is needed, all the good characteristics are passed onto the offsprings

disadvantages of asexual reproduction

the offspring gets all the negative characteristics, there is a lack of dispersal competition (nutrients, water, light), little variation adaption into a new environment is unlikely

tuber definition

extension of the parent

sexual reproduction

involves both parents and relies on the production and fusing of special sex cells known as gametes. the gametes must come together in the process of fertilisation to successfully produce offspring. the offsprings unlike asexual reproduction are not clones of the parent(s), but rather a mixture of both parents.

gametes (extensive definition)

the main reason for genetic mixing in the offspring is that gametes only contain diploid of the genetic makeup of the parent. gametes are produced from a type of cell division known as meiosis.

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every gamete is described as being a haploid cell. haploid mans that only half of the genes are present in that cell. the haploid gametes are sperm, pollen and egg cells.

example of gametes

in a somatic cell (i.e skin cell), the normal number of chromosomes for humans is 46. however, in a sperm cell, there is only half that number, 23 chromosomes and this is the same for the female’s egg cell. they also contain 23 chromosomes.

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when fertilisation takes place both sets of the 23 chromosomes pair up to make a normal zygote fertilised egg cell. from this point onwards, the fertilised cell is called a zygote. in this way, the offspring becomes a half of the genetic information from two parents. (there are the exception of identical twins that share the same genetic information)

advantages of sexual reproduction

high genetic variability, facilitates adaption, ‘speed's’ up evolution

disadvantages of sexual reproduction

energy costly, courtship is time/resource consuming, usually sacrifices the fitness of one sex to the other

gamete

the reproductive cell of a plant/animal

zygote

a fertilised egg