C2 Chemical Bonding

C2 Chemical Bonding

“Welcome, folks, to the Atoms Administration.”

 

Ions are charged particles that have an excess or deficiency of electrons. Elements form ions by gaining or losing electrons in attempt to achieve a full outer shell. Metals form positively charged ions, cations and non metals negatively charged ions, anions.

 

Ionic bonding is the type of bonding between a metal and a non-metal including formation of ions and electrostatic attraction between them. They occur in lattice structure, a regular arrangement of alternating positive and negative ions, such as sodium chloride table salt. It is very strong. An ionic reaction is a redox reaction in that one compound gains electron and the other loses electrons.

 

Molecules and covalent bonds.

Non-metallic elements form covalent bonds with each other, in which electron is shared between atoms.

 

	Ionic	Covalent
Melting point	high	low
Volatility	higher	lower
Solubility	Generally soluble to form solutions that conducts electricity	Insoluble in water and solutions in other solvents will not conduct electricity
Electrical conductivity	Conducts when molten / liquid, when there is a sea of delocalized electrons	never
Structure	Solid: positive negative ions attracts together to form regular 3D ionic lattice. Strong, regular structure is produced, crystalline solid that has a high melting point. Liquid: contains free-moving ions that conducts electricity.	Solid: Atoms bond into molecules held together by weak forces of attraction, hence low melting point. Liquid: has free moving molecules and hence does not conduct electricity.

 

Giant structures

 

Giant covalent structures are massive networks of covalently bonded molecules that has a regular repeating pattern in which many lattice structures occur. Examples are diamonds and graphite, which are allotropes of carbon. Diamonds have 4 carbon bonds while graphite has 3.

 

Diamond is very hard and a hexagonal structure is created around each carbon atom. They have very strong covalent bonds.

 

Graphite occurs in layers and in each layer, each atom is bonded to 3 bonds and forms a hexagonal shape. There is a 1 free electron from each carbon atom. The bonds between the layers are not strong covalent bonds but weak intermolecular forces due to free electrons. Hence, graphite is used in pencils and lubricants since layers can slide off each other and it rubs off each other. Layers of graphite come onto the paper.

 

Silicon dioxide also makes hexagons, each silicon is bonded to 4 oxygen atoms covalently. Each oxygen atom is bonded to 2 silicon atoms. It is a giant covalent structure and it has strong bonds. It is a lattice structure that continues in 3D with regular patterns.

 

Structure of a substance determines its physical properties.

 

	Diamond	Graphite
Hardness	The hardest known substance	Soft and slippery
Melting point	>3500C
Appearance	Transparent, shiny and sparkly	Opaque, dull, black/silver
Conductivity	Does not conduct electricity	Conductor
Uses	Jewellery, cutting, drill heads	Lead in pencils, lubricant

 

Metallic bonding

 

Metals conduct electricity because there is a lattice of positive metal ions in a sea of delocalized electrons in a tightly packed regular structure, in which electricity can flow freely. Ions are held together by attraction to bonding electrons.

 

Malleability is due to non-directional metallic bonds since bonding electrons are free to move, making them easy to bend.

 

C1 Particles and the Periodic Table

C1 Particles and the Periodic Table

 

Atom is the smallest unit of an element, all matter is composed of atoms, has a nucleus with protons and neutrons and electrons on its shells.

Molecule is the smallest physical unit of a chemical compound.

Physical changes do not change the chemical composition of a substance, e.g. change of state, change of shape. No bonds are broken but intermolecular forces between molecules are broken.

Chemical changes makes a new substance in that bonding happens. Atoms of the elements are rearranged.

Elements are composed of one single type of atoms with the same number of protons.

Compounds are two or more atoms bonded together.

Mixtures are congregation of two or more substances that do not bond together. The product of the random distribution of one substance through another without any chemical reaction, as distinct from a compound.

 

Atomic structure

An atom has a nucleus, containing protons and neutrons, and shells on which electrons form.

 

	Relative Charge	Relative mass
Protons	+1	1
Neutrons	0	1
Electrons	-1	negligible

 

Proton number/atomic number is the number of protons in an atom.

Nucleon number is the # of protons and neutrons in an atom.

Periodic table is arranged in ascending shells and valence electrons, etc. Noble gases do not react because they have no valency electrons, a full outer shell.

Isotopes are atoms of the same element with the same proton number but different # of neutrons.

Relative atomic mass Ar is a comparison of a mass of an element to an atom of carbon-12, and the relative atomic mass always equals the nucleon number on the periodic table.

Destruction oxidation

 

Metal oxides are basic and most non-metal oxides are acidic. If non-metal oxides are not acidic, they are neutral (such as pure water). Some oxides of metals can behave as acidic even though they are basic. They are called amphoteric oxides.

 

Some elements are metalloids, intermediate between metal and non metal.

 

Metals	Non-metals
Metallic sheen, glossy	Dull and light
High density	Low density
Good electrical and heat conductor	Poor conducter
Strong	Weak
Malleable	Brittle

 

Group # = # of valence electrons. 1-3 Metals, 4-8 non-metals.

 

G1 Alkali metals

 

Lithium, sodium and potassium are a collection of relatively soft metals that are solid at room temperature and reacts violently with water to form strong alkali solutions

 

Reactivity increases down the group because elements with more shells are less stable. Melting points and hardness of G1 metals decreases down the group.

 

They FFMM, Fizz Float Melt Move on water’s surface.

 

G7 Halogens

 

Halogen reactivity is highest at top of the group. Chlorine will displace every halogen below it. Chlorine is yellow-green, bromine is red, iodine is brown-black.

 

G8 Noble gases

They are unreactive and they are useful to provide an inert atmosphere, where reaction is not desired. I.e. Argon in lamps, and helium for filling balloons.

 

Transition metals
They are a collection of metals having high densities and melting points that form colorful compounds and often act as catalysts.

Chemistry

Chemistry is a subject about Taoism, political spectra and intuition. Here are the units taught en mi escuela.

C1 Particles and the Periodic Table

C2 Chemical Bonding

C3 Rates and Energetics

C4 Stoichiometry

C5 Acids n Pollution

C6 Detective Chemistry

C7 Reactivity

C8 Organic Chemistry

 

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B8 Inheritance

B8 Inheritance

Types of variation

Variation is the small differences that exist between members of the same species.

Continuous variation is influenced by both genes and environment, resulting in a range of phenotypes between extremes that are usually bell curved. E.g. height, weight.

Discontinuous variation is caused by genes alone and results in a limited number of distinct phenotypes with no intermediates. E.g. blood type, eye color

Generating genetics

DNA is a carrier of genetic information that is capable of self replicating.

Genes is a length of DNA that is the unit of heredity, codes for a specific protein. Can be copied and passed on to the next generation.

Chromosome is a thread of DNA that is made up of a string of genes.

Inheritance is the transmission of genetic information through generations.

Chromosome > genes > DNA.

Haploid means having a single set of unpaired chromosomes.

Diploid means containing 2 complete sets of chromosomes, one from each parent.

Gamete is a mature haploid male or female germ cell which is able to unite with another of the opposite sex in sexual reproduction to form a zygote.

Zygote is a diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum.

Cell division

Mitosis makes body cells with 46 chromosomes.

The nuclear division giving rise to genetically identical cells in which chromosome # is maintained by exact duplication. Look at notebook for details.

Meiosis makes sex cells with 23 chromosomes. It is reduction division where chromosome # is halved from diploid to haploid, and it happens during gamete production. Consult notebook for pretty pictures.

They are important becauses mitosis is for growth and repair while meiosis is for reproduction.

Inheritance

Phenotype is the ‘phenomenon’ – outcome of a certain genetic trait.

Genotype is the specific genes the organism has. (e.g. female XX male XY)

Alleles are 2+ alternative forms of a gene that codes for the same proteins.

Homozygous refers to an individual that has 2 identical alleles of a gene.

Heterozygous refers to having 2 different alleles of a gene.

Dominant refers to a gene is expressed in offspring even when inherited from only one parent.

Recessive refers to a gene that is expressed only when inherited from both parents.

I can draw punnett squares and so can you.

Sex is determined by X and Y sex chromosomes. A female has 2 x chromosomes and eggs only carry an X chromosome. Male has 1 X and 1 Y, and sperm carries either X or Y chromosome. The whole Chromosome is used in the cross rather than the alleles of a gene.

Mutation

Mutation is a change in gene/chromosome caused by chemical/random/radiation.

E.g. sickle cell anemia that causes the red blood cell to take another shape, caused by mutation in gene that codes for hemoglobin.

Artificial selection

People choose the characteristics they want to appear in the next generation. You can do this to everything that breeds except people, because that is very unethical.

E.g. Cattles may be bread for quantity/quality of milk/meat

Sheeps for quant/qual of wool

Plants for taste/pest tolerance/drought tolerance.

Selective breeding

Is when you select two parents with ideal traits and breed them together to pass on those traits. E.g. I take the sweetest strawberries and the biggest strawberries and breed them together so I get both genetic characteristics, I am a perfect strawberry yay.

Natural selection

The process whereby organisms better adapted to their environment tend to survive and produce more offspring, and this is how evolution happens over successive generations. Variation in different members of the same species cause some to be better adapted, and overpopulation ensures that some survive. Better genes get passed on.

Evolution is change in the heritable characteristics of biological populations over successive generations.

Antibiotic resistance

Similarly, the overuse of antibiotics may cause bacteria that are resistant to everything because they have survived over the usage and evolved. They are called superbugs.

B7 Plant and Human Reproduction

B7 Plant and Human Re-production

Asexual reproduction

Asexual reproduction is the process resulting in the production of genetically identical offspring from one parent. Examples: bacteria, sea stars, yeast, strawberry

Advantages	Disadvantages
Speed Preserve desirable characteristics No need to find another partner	Disease may kill everyone No genetic diversity Increased competition between offspring

 

Sexual reproduction is the process involving the fusion of haploid nuclei to form a diploid zygote and the production of genetically dissimilar offspring.

Advantages	Disadvantages
Genetic diversity Increased chances of survival Unique offspring Can adapt to environment better	Speed is slow due to 2 partners required Time and energy to find mate Fewer offspring

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Flowers for Algenon

Structure	Function
Sepals	Protect the unopened flower
Petals	Brightly colored to attract insects
Anthers	Making and storage of pollen, male gametes
Stigmas	Catches pollen grains for temporary storage
Ovaries	Contains ovules, female gametes

 

Pollination is the transfer of pollen grains from the male part of the plant (anther of stamen) to the female part of the plant (stigma.)

Some agents of pollination are wind, water, animals (like bees/insects and humans.)

 

Structural adaptations of insect-pollinated and wind-pollinated flowers

 

Insect pollinated	Wind pollinated
Large, bright, conspicuous petals	Small or none at all
Strongly scented	No scent
Nectaries at base of petals for insects	No nectaries
Anthers within flower for insects to brush past when reaching for nectar	Anthers outside
Stigma within flower for insects to brush past when reaching for nectar	Stigmas large and outside petals
Sticky, spiky pollen grains	Smooth, light pollen grains
Many pollen produced	Even more pollen produced

 

Seed germination

 

Factor affecting germination	Why
Oxygen	Needed for respiration and chemical changes for mobilization of food reserves.
Water	Absorbed through micropyle, needed to activate enzymes which convert insoluble food stores into soluble nutrition needed for growth and energy.
Temperature	For enzymes to work at their optimum temperature
(Light)	Not a requirement but some seeds need some exposure to light before germination

 

Structure of seeds and function

 

Radicle, Plumule and cotyledons is the embryo of the seed.

Structure	Function
Radicle	Grows as root
Plumule	Grows as shoot
Cotyledons	Food storage
Testa	Hard outer protective layer

 

Seed dispersal

Seed and fruit dispersal by wind and animals provides a means of colonising new areas, prevention of local competition.

 

Dispersal by wind: dandelions seeds are blown away by wind.

Dispersal by animals: Fruits such as apples, berries are eaten by animals, their seeds are inedible and therefore excreted/uneaten and carried by the animal to new areas; alternatively hooked fruits like rambutan can stick to the animal’s fur and be carried away.

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Sexual reproduction in humans

 

Structure	Function
Penis	Introducing the sperm cells into the vagina during intercourse
Sperm ducts	Conveys sperm to the urethra
Urethra	Leads the sperms to the outside through the penis
Scrotum	Sac that holds testes and suspended outside body to have cooler conditions for sperm production
Prostate gland	Produces a fluid to nourish the sperm cells and help them swim vigorously, this fluid together with sperm is called semen
Testes	Produces sperm from their coiled tubes and makes the sex hormone

 

Structure	Function
Uterus	For the implantation and development of the embryo
Vagina	Receive sperm cells during intercourse and birth canal
Oviduct	Lead mature ova to the uterus, region where fertilisation takes place
Ovary	Produces eggs at puberty and also female sex hormones
Cervix	Connects uterus to vagina

 

Male and female gametes

Ovum/egg has cytoplasm, and a layer of jelly between membrane, and nucleus containing chromosomes.

Sperm cell has tail, midpiece, mitochondria in midpiece, nucleus in head. Energy for swimming is produced in mitochondria.

 

	Ovum/egg	Sperm
Size	Large; visible to the human eye	Very small
Numbers/amount	One produced every month	Many millions produced
Mobility	Pushed around the oviduct	Has a tail to move

 

Menstruation

 

Occurs every 29 days and controlled by oestroen and progesterone produced in the ovary.

1. Period arrives and lasts for 5 days. Lining of the uterous breaks down and blood/cells past out of the vagina.
2. Day 6 – a new ovum starts to develop in the ovary. Ovum develops a sac of fluid around it to be called a follicle. Follicle releases oestrogen to repair the lining of the uterus.
3. Ovum is released – ovulation at day 14. Remaining follicle releases a different hormone that maintains the lining of the uterus should fertilisation occur. The lining is thickened to increase chances of implantation.
4. Next 7 days is the receptive stage and fertilisation will cause embryo to be implaced in the lining. If not fertilized, ovum dies and passes out of the vagina.
5. Low level of prosgesterone leads to the uterus lining being shed and cycle starts again.

 

Fertilisation in humans

 

It’s the fusing together of sperm and ovum nuclei.

 

Sperms will swim through the uterus and up to the oviducts to fetilize.

 

After fertilisation takes place in the oviduct, the fertilized ovum/zygote begins to divide, forming a ball of cells that starts to move down the oviduct into uterus, becoming an embryo. Implantation occurs when embryo sinks into soft lining of uterus.

 

Function of a bunch of things related to pregnancy

 

Structure	Function
Amniotic sac	Produces the amnionic fluid and encloses the fluid (rupturing just before birth)
Amniotic fluid	Prevents fetus from drying out, prevents temperature fluctuations and unequal pressures acting on the fetus, acts as a shock absorber to prevent physical damage
Placenta	Supplies the fetus with oxygen and nutrients, to be dissolved in blood
Umbilical cord	it supplies oxygen, it delivers nutrients, and it helps to withdraw blood rich in carbon dioxide and depleted in nutrients (excretory products)

Breastfeeding

 

Advantages	Disadvantages
Antibodies in breast milk can pass immunity from mother to child; No preservatives or additives; Does not contain bad bacteria. Free compared to formula milk	Uncomfortable for mother Needs mother to be present for feeding

 

Bottle-feeding formula milk

 

Advantages	Disadvantages
Someone else can feed the baby Often enhanced with nutrients	No antibodies May be contaminated if not stored correctly Expensive

 

HIV/AIDS

 

HIV is transmitted in blood and semen, etc.

Methods of transmission	Prevention
Unprotected sex with infected person	Usage of condoms; abstinence
Drug use while sharing a needle with infected person	Don’t take drugs they bad for you / use sterilized needles
Transfusions of unscreened blood	Screen the bloody blood
Infected mother to child	Feed a baby with bottle milk
Use of unsterilized surgery instruments	Sterilize them

 

How does it affect immune system?

1. HIV virus lowers the amount of lymphocytes called CD4 cells.
2. Once a person’s CD4 cell count is low, opportunistic diseases start making a person sick, and these symptoms are called AIDS. common ones are herpes and fungal infections.
3. Weakens the immune system and makes it defunct without medicine.

B6 Coordination and Response

Nervous control in humans

The human nervous system is the central nervous system (brain and spinal cord as areas of coordination) and the peripheral nervous system which together serve to coordinate and regulate body functions.

Central nervous system is brain and spinal chord.

Peripheral nervous system is made of nerves which are collections of many long thin nerve cells called neurons.

1. When exposed to stimulus, sensory neurons generate an electrical impulse that is passed along from PNS to CNS to trigger a response.
2. The response travels from relay neurons to effector muscles or glands.

Part	Function
Dendrites	Collects electrical signals
Cell body	Integrates incoming signals and generates outgoing signal to axon
Axon	Passes electrical signals to dendrites of another cell or effector.
Cytoplasm	Is elongated to transmit over long distances
Myelin sheath	Insulates neurons from other cells so transmission is more efficient
Synapses	a junction between two nerve cells, consisting of a small gap across which impulses pass by diffusion of a neurotransmitter.

Neurones

Motor neurons(effector): transmits impulses fron CNS to effectors which are muscles or glands.

Relay (connector) neurons: lies in the CNS and makes connections with other neurones. Sensory neurones: Has receptor at one end and carries impulses to the CNS – brain and spinal cord.

Reflex arc are pre-set nerve pathways where same stimulus always results in the same response, defining stimulus is anything that causes the nervous system to produce a response.

Stimulus → receptor → coordinator (spinal cord) → effector → response.

A reflex action is a means of automatically and rapidly integrating and coordinating stimuli with responses.

1. They are involuntary.
2. Occur to protect body from harm.
3. Frequently involve only 2-3 neurons.

M-eye eye bel-eyed the r-eye-tful l-eye-fe

Structure of eye

Function of eye

Structure	Function
Pupil	Hole in center of iris that controls the amount of light to strike the retina.
Iris	A coloured ring of circular and radial muscle that control size of pupil
Lens	Biconvex structure that refracts light to be focused on retina with cornea.
Cornea	Thick transparent membrane at front of eye that refracts the light entering
Suspensory ligament	Muscles that attach the lens to the ciliary body to hold it in place
Ciliary body	Muscles that control the shape of the lens to allow focusing
Aqueous humour	Fluid secreted from ciliary body filled between lens and cornea, supplies nutrition
Vitreous humour	Gel behind lens and in front of retina, provides support and refracting media
Conjunctiva	Membrane that covers sclera, protects the eye through lubrication
Sclera	White of the eye, protects the eye
Choroid	Connective tissue between retina and sclera, Produces a black pigment to prevent reflection of light inside the eye
Retina	Layer of light sensitive cells that convert stimuli into signals with energy, has rods and cones
Yellow spot fovea	Near center of retina around fovea, the area of best vision, An area of the retina containing a high concentration of cones, where light is usually focused and colours are detected
Blind spot	Part of the retina in front of the optic nerve that lacks rods or cones
Optic nerve	Transmits electrical impulses from the retina to the brain
Rods	Sensitive to dim light, do not respond to colour
Cones	Detects colours in bright light

 

Eye accommodation

TO DO WITH NEAR/FAR OBJECTS

Amount of refraction of light reaching the eye depends on distance between object and eye. Altering its focus for near and distant objects is called accommodation.

Eye alters the thickness/focal length of its elastic lens with ciliary muscle and suspensory ligaments.

	Near	Far
Lens	Thicker/rounder	Thinner
Ciliary Muscle	Contracts	Relaxes
Suspensory ligament	Relaxes	Contracts

An eye is unaccommodated when looking at distant things. I know this from my-opia.

Pupil reflex

TO DO WITH LIGHT/DARK ENVIRONMENT

Size of pupil changes in bright or dim light. This change is a reflex action.

Iris contains radial muscles (which goes around the iris) and circular muscles (which runs from center of iris to outside). When muscle contracts they get shorter.

	Bright	Dark
Pupil	Constricted/small	Dilated/big
Circular Muscle	Contracts	Relaxes
Radial muscles	Relaxes	Contracts

Hormones: the bane of human existence

A hormone is a chemical substance produced by a gland carried by the blood that alters the activity of one or more specific target organs and is then destroyed by the liver forever.

They are chemical messengers.

Glands that make hormones are a part of the endocrine system.

Examples of hormones: insulin by pancreas for liver, estrogen by ovary for uterus.

One important hormone is called adrenaline is produced in adrenal glands above kidneys. 上肾腺素。Chinese is a much better language when it comes to sciences, you see, it literally says ‘above kidney gland magic juice. It is secreted directly in the blood stream and actions are very rapid, lasts for a short time.

Adrenaline increases blood glucose concentration and pulse rate to have chemical control over metabolic activity.

Examples of situations where adrenaline secretion increases: sports, nervousness, danger, first dates, and most of all IGCSE exams

Differences between nervous and endocrine system

Thingamajig	Nervous system	Endocrine system
Speed du action	fast	slow
Nature of message	Immediate response	Change actions or states
Duration du reponse	short	longer
Area of response	local	wider
Examples of processes controlled	Reflexes	Blood sugar concentration
Form of transmission	Electric	Chemical

Romeo amazes at Homeostasis

Homeostasis is the maintenance of a constant internal environment. It’s important because blood and tissue fluid needs to stay constant. And enzymes need to have optimum conditions.

Maintaining temperature sans air conditioner

Hair is hair. Sweat glands are the fur ball underneath a pore.

Temperature receptors are round things at the bottom.

Blood vessels are the webby stuff.

Fatty tissue are the bubbly stuff.

We are endothermic as we maintain constant body temperature, unlike ectothermic snakes. They are bad people,.

A temperature control center in hypothalamus in brain. Subcutaneous (under the skin fat) fat helps by providing nerve passageway and storage of energy.

	Hot	Cold
Heat loss	Increases	Decreases
Sweat glands	Secret and evaporate sweat	No sweat of course lol
Surface capillaries	Vasodilates to radiate heat	Vasoconstriction shuts blood away from skin to prevent radiation
Hair erector	Relaxes, flat hair convects heat	Contracts, raises hair and traps layer of still air, prevents convection

Negative feedback

Homeostasis involves control by negative feedback, in which a change sets off a response that cancels out the change.

1. A change from normal conditions trigger a sensor that stimulates response.
2. If response is not stopped, it would tip the normal from the other end.
3. Hence, sensors detect the normality and tells effector to stop response.

Ensures that changes are reversed and promotes stability.

Glucose control by liver

1. Blood sugar is controlled by hormones made in the pancreas.
2. Blood glucose level is detected in the pancreas.
   1. If too high:
      1. Pancreas makes more insulin.
      2. Insulin is secreted by the pancreas to stimulate the removal of glucose from the blood by liver cells.
      3. Liver converts glucose to insoluble glycogen, removing them from blood.
      4. Blood glucose level returns to normal.
   2. If too low:
      1. Pancreas produces less insulin and secretes glucagon, a hormone that stimulates the release of glucose into blood to breakdown glycogen to glucose.
      2. Blood sugar concentration rises to normal..

Now onto plants and light we go

Geotropism is a response in which a plant in response to gravity; positive being downwards and negative being upwards;

1. Auxin is made by root tip.
2. Auxin builds up on the lower side towards gravity.
3. Auxin causes cell to elongate less on the lower side and grow towards gravity.

Phototropism is a response in which a plant grows in response to direction of light source.

1. Auxin made by shoot tip.
2. Auxin passes down the shaded side.
3. Auxin makes cells elongate more on the shaded side, the shoot bent wards the light.

This is controlled by auxins. They move by diffusions.

B5 Human Transport and Exchange

The circulatory system

The circulatory system is a system of tubes with a pump and valves to ensure one-way flow of blood.

Organisms could have single or double circulatory systems.

Double circulation is a low pressure circulation to the lungs, which is meant to pick up oxygen, and a high pressure circulation to the body tissues, which is meant to deliver oxygen. We have double circulation because we are big animals.

 

Effect of physical activity on pulse rate

More physical activity means higher pulse rate because the body needs more oxygen for movement and the heart works to deliver more oxygen to the body organs.

 

Blood in the heart

(septum is the middle separation muscle)

1. Deoxygenated blood enter the right atrium via superior and inferior vena cava.
2. Blood is pumped into the right ventricle.
3. Blood is pumped out of the heart towards the lungs through the pulmonary artery.
4. Oxygenated blood enters the left atrium through the pulmonary vein.
5. Blood is pumped into the left ventricle.
6. Blood is pumped towards the body through the aorta.

 

Blood vessels

 

Coronary heart disease

Little blood vessels feeding oxygen to the heart (coronary arteries) is clogged.

May lead to heart attacks.

Causes: Too much saturated fats, smoking, stress.

Preventative measures: Eat less saturated fats, don’t smoke, exercise, meditate

 

Blood vessels

Artery

• Thick muscular walls to resist high pressure
• Elastic muscular walls to produce pressure and assist blood flow
• Small lumen

Vein

• Thinner muscular wall
• Larger lumen
• Valves to prevent blood backflow

Capillaries

• One cell thick to allow diffusion

 

Composition of Blood

• Red blood cells: transports oxygen and carbon dioxide
  • Small size: fits into capillaries
  • Biconcave shape: maximizes surface area for oxygen absorption
  • No nucleus: fits more hemoglobin
  • Contains hemoglobin: it binds with oxygen
• White blood cells (phagocytes; lymphocytes): defends the body against diseases
  • Phagocytes phagocytosis.
  • Lymphocytes make antibodies.
• Plasma: dissolves blood cells, ions, soluble nutrients, hormones and CO2 to allow transport
• Platelets: stops bleeding by clumping near a wound

 

Immune system

White blood cells guard the body against invasions.

Phagocytes: Engulfs pathogens (all foreign cells) and digests them. This is called phagocytosis.

Lymphocytes: Makes and releases antibodies towards the antigens on the pathogens, binding them together, paralyzing them for phagocytes to digest them.

Tissue rejection with immune system

If a person needs organ transplant, immune system will recognize the new organ as foreign and starts attacking it. It may trigger a response and antibodies may be produced. When this happens, it’s called tissue rejection. You can prevent this by using a relative’s organ or suppressing your immune system (but not your emotions. Let’em out sister)

 

Gas exchange

 

Alveolus has large surface area and a thin wall to allow maximum diffusion across.

It is moist so cells would not dry and gases can dissolve.

There is a high concentration gradient due to blood movement.

Mucus is made by goblet cells to trap bacteria, while cilia hair sweeps the mucus away.

 

Inspired air has more oxygen and less carbon dioxide. Expired air has more carbon dioxide and water and less oxygen. To confirm, bubble expired air through limewater for white precipitate.

 

Don’t smoke

Components of tobacco	Effects
Tar	Increases risk of cancer, causing bronchitis and damages cilia, coating and lining air passages
Nicotine	Addictive and increases heart rate and blood pressure
Carbon monoxide	Combines with hemoglobin to prevent oxygen cells being transported; could die
Smoke particles	Irritates air passages and results in chronic bronchitis, coughing, etc.

 

Effects of physical activity on rate and depth of breathing

Higher physical activity leads to quicker and deeper breathing due to the need for oxygen for muscles to release energy.

 

Respiration

 

Respiration is the chemical reactions that break down nutrient molecules in living cells to release energy.

 

How is energy used in humans?

• Muscle contraction
• Protein synthesis
• Cell division
• Growth
• Passage of nerve impulses
• Maintenance of constant body temperature.

 

Aerobic respiration: Is the release of a relatively large amount of energy through breaking down food substances in cells in presence of oxygen. Occurs when excess oxygen is present.

Equation: C6H12O6 + 6O2 → 6CO2 + 6H2O

Anaerobic respiration: Is the release of a relatively small amount of energy through breaking down food substances in cells in absence of oxygen. Occurs when there is a lack of oxygen. Breaks down glucose into lactic acid (a toxin), causes muscle cramp and creates oxygen deficit that will need to be later recovered through aerobic respiration. Extra oxygen breathed in after anaerobic respiration is used to break lactic acid down to water and carbon dioxide.

Equation: C6H12O6 → 2C3H6O3

 

Anaerobic respiration in yeast

In brewing:

1. Yeast is dissolved in warm sugar solution.
2. Yeast respires anaerobically to release ethanol and carbon dioxide, making the drink alcoholic and fizzy. This process is called fermentation.

In making bread:

1. Yeast is mixed with sugar and water.
2. Flour is added to make dough and left to warm.
3. The dough rises as yeast releases carbon dioxide which creates air bubbles in bread.
4. High temperature when baking kills the yeast and evaporates alcohol.

In yeast equation: glucose → alcohol + carbon dioxide

English

Literature

Literature is a subject about romanticizing, sentence making and word wrangling. I once liked Nora, but now she tires me. I guess that is how marriage works. Here are the things taught en mi escuela.

Paper 2 Unseen: My examples

Paper 3 Dollhouse: Overall Essays, Excerpt Essays, Notes (To be written)

Language

Language is a subject about guessing, gibberish writing and mundane thinking. Here are the things taught en mi escuela.

everything to be written