Biology 2

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  • Created by: Jasmine
  • Created on: 23-02-13 13:42

Aerobic Respiration

  • Releases energy from food
  • Takes place in mitochondria
  • A chemical process in you lungs
  • Mitochondria contain many different enzymes which control the process of respiration.
  • Muscle cells contain a lot of mitochondria as they do alot of activity.
  • Needs oxygen and produces carbon dioxide.
  • Provides more enrgy than anaerobic respiration.
  • Glucose + Oxygen ------- Carbon Dioxide + Water

It happens -

  • To allow muscles to contract
  • To build larger molecules from smaller ones
  • In plants - to build sugars, nitrates and other nutrients into amino acids
  • In mammals - to maintain a constant body temperature
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Anaerobic Respiration

  • Produces less energy
  • Happens in the cytoplasm
  • Glucose -------- Latic Acid
  • Doesn't need oxygen
  • Latic acid builds up in muscle cells, causing ache and cramp.
  • Latic acid needs to be broken down into carbon dioixde and water, which can be carried away by the blood, breking it down requires oxygen so we talk about an oxygen debt that needs to be repaid
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Animal and Plant Cells

  • All animals and plants are made of cells
  • Plants cell wall is made of cellulose, it gives support so the cells can form a large, strong structure.
  • Animal cells have - cytoplasm, nucleus, ribosomes, mitochondria, cell membrane
  • Plant cells have - cell wall, cell membrane, nucleus, vacuole, cytoplasm, chorophyll, chloroplast, mitochondria
  • Bacteria cells have - flagellum, chromosomal DNA, Nucleoid DNA, cytoplasm, plasma membrane, cell wall, capsule, plasmid
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Blood Cells

Red Blood Cells

  • Carry haemoglobin which when combined with oxygen forms oxyhaeoglobin
  • Doesn't have a nucleus
  • Carries iron

White Blood Cells

  • Can ingest pathogens and destroy them
  • Produce antibodies to destroy particular pathogens
  • Produce antitoxins that counteract the toxins released by pathogens.


  • The liquid which transports everything
  • Carries white blood cells, red blood cells, platelets, hormones, cells waste products and carbon dioxide.
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  • Found in nucleus of cell
  • 23 pairs of chromosome
  • A section of this is DNA
  • A small section of DNA is a gene
  • 2 distinct strands - like a twisted ladder - double helix
  • 2 strands held together by chemical bases
  • There are four bases - Adenine + Thymine, Cytosine + Guanine
  • The base pairs are joined by a weak hydrogen bond
  • A gene is a section of DNA and the sequence of bases in a gene code for a specific protein.
  • Franklin and Wilkins worked out helical structure by directing beams of x-rays onto crystallised DNA and looked at the patterns the x-rays formed as they bounced off.
  • Watson and Crick used these ideas, along with the knowledge that the amount of adenine and guanine was matched with the amount of thymine and cytosine to make a model of the DNA molecule where all the pieces fitted together.
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Animal Cells have

  • nucleus - contains DNA that controls what the cell does
  • cell membrane - holds the cell together and controls what goes in/out of the cell
  • cytoplasm - gel-like substance where most of the chemical reactions happen
  • mitochondria - these are where most of the reactions for respriation take place.

Plant cells have

  • nucleus - contains DNA that controls what the cell does
  • cell wall - made of cellulose, gives support for the cell
  • large vacuole - contains sap, a weak solution of sugar and salts
  • chloroplasts - where photosynthesis occurs, they contain a green substance called chlorophyll.
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Bacterial Cells have

  • chromosomal DNA(one long circular chromosome) - controls the cells activities and replication, it floats free in the cytoplasm (not in a nucleus)
  • plasmids - small loops of extra DNA that aren't part of the chromosome, they contain genes for things like drug resistance and can be passed between bacteria
  • flagellum - long hair-like structure that rotates to make the bacterium move
  • cell wall - supports the cell
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  • Nuclues - chromosome - DNA - gene
  • has a distinctive double helix shape
  • the 2 strands are held together by chemicals called bases
  • 4 bases
  • Adenine + Thymine
  • Guanine + Cytosine
  • the base pairs are joined together by a weak hydrogen bond
  • a gene is a section of DNA, and the sequence of bases in a gene code for a specific protein
  • Franklin and Wilkins worked out the helical structure by bouncing x-rays off crystallised DNA and looking at the pattern the z-rays formed as they bounced off
  • Watson and Crick used that knowledge as well as the fact that they knew the amount of adenine and thymine matched the amount of guanine and cytosine, to make a model of the DNA molecule where all the pieces fitted together.
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Protein Synthesis


  • unzip DNA
  • MRNA goes into make a copy


  • MRNA goes into ribosome
  • TRNA attaches onto groups of 3 bases
  • on top of TRNA is animo acid
  • MRNA moves along so translation can continue to occur
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  • catalysts produced by living things
  • all proteins
  • DNA replication - enzymes help copy a cell's DNA before it divides by mitosis or meiosis
  • protein synthesis - enzymes hold enzymes in place and form bonds between them
  • digestion - various enzymes are secreted into the gut to digest different food molecules
  • the substrate is the molecule being changed in the reaction
  • Enzymes only work on one substrate
  • this is due to the fact the active site is a particular shape and if it gets damaged it is said to be denatured
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Human Genome Project

Thousands of scienctists collaborated to try to find every single human gene.

Good things about HGP

  • Predict and Prevent Diseases
  • Develop new and better medicines
  • Accurate diagnoses
  • Improve forensic science

Bad things about HGP

  • Increased stress - if someone knew they had the gene which could cause a genetic disease, even if they never get it, they could worry about it
  • People who are 'carriers' could be put under pressure not to have children incase they pass the disease on
  • Possible employers and insurance companies could discriminate against people who could develop a genetic disease at some point in the future
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Genetic Engineering

The process:

· Cut out the insulin gene from the DNA of a human cell using an enzyme.

· Remove a ring of DNA from a bacterium and open it up using the same enzyme.

· Insert the insulin gene into the plasmid using another enzyme.

· Enable a bacterium to take up the altered DNA.

· Put the bacterium in a fermenter, and it multiplies many times.

· Each new bacterium contains the insulin gene.

· The bacteria produce insulin which can be extracted.

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MITWOSIS produces 2 genetically identical body cells.

Definition: a type of cell division used to produce new body cells. Occurs during growth and repair, or to produce replacement cells. Used in ASEXUAL REPRODUCTION of simple plants and animals.

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MEosis Me - how was i made? SEXUAL REPRODUCTION.

Definition: Special type of cell division used to make sex cells. Gamates have half the normal number of chromosomes.

Produces 4 non identical cells (unless identical twins).

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Similarities between Mitosis and Meiosis


miTWOsis and MEosis both.....

  • are a type of cell division
  • the replication (copying) of chromosomes occurs before division
  • begin with M :D
  • equal number of chromosomes at first divisions.
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Differences between Mitosis and Meiosis


  • Mitosis produces more offspring
  • produces 2 cells
  • used in asexual reproduction,
  • includes one nucleur cell division
  • resulting cells are genetically identical - NO VARIATION
  • simple cell division.
  • Meiosis produces fewer offspring
  • produces 4 cells
  • used in sexual reproduction
  • includes two nucleur divisions
  • not genetically identical - VARIATION
  • cell division for gametes
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About Cloning

What is Cloning?

Cloning is the creation of an organism, that is genetically identical to another thing. (Genetically identical individuals)

Bacteria, plants and some animals can reproduce asexually to form clones that are genetically identical to their parent.

Identical human twins are also clones: any differences between them are due to environmental factors.

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Asexual Reproduction

Asexual reproduction only requires one parent , unlike sexual reproduction, which needs two. Since there is only one parent, there is no fusion of gametes, and no mixing of genetic information. As a result, the offspring are genetically identical to the parent, and to each other - so they are clones.

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Cloning in Plants

There are many different forms of asexual reproduction in plants. Many plants develop underground-food storage organs that later develop into the following year’s plants. Potato plants and daffodil plants do this.

the flower bud is at the centre of the bulb, and a lateral bud is at the side ( of leaves are now where the flower bud was, and a new plant has begun to grow from the lateral bud  (

Daffodil bulb at start of season     Daffodil bulb at the end of season

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Cloning in Plants continued


Strawberry plant with runners - stems growing sideways

Some plants produce side branches with plantlets on them. The Busy Lizzie plant does this. Others, such as strawberry plants, produce runners with plantlets on them. This is shown opposite.

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Cloning in Animals

Asexual reproduction in animals is less common than sexual reproduction but it does happen in sea anemones and for example, starfish.

Natural Cloning

Twins are genetically identical because they are formed after one egg cell is fertilised but splits to form two embryos. They have the same genes. As the genes came from both parents they are not clones of either parent, but they are natural clones of each other

Artificial Cloning

It is in fact possible to make clones artificially. The cloning of animals has many important commercial implications. It allows an individual animal that has desirable features, such as a cow that produces a lot of milk, to be duplicated several times.

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Osmosis is when water moves from an area of high concentration of water to an area of low concentration of water through a semi-permeable membrane such as a cell membrane in an animal cell. Specifically, it is the diffusion of water as opposed to the diffusion to a solution. This allows cells to take in the correct amount of water and allow the correct amount of water to leave the cell. This means that the cell does not become 'turgid' and burst.The diagram below shows how osmosis occurs.


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Plants and Minerals

Plants need to take in a number of elements to stay alive. The most important are: Carbon, Hydrogen and Oxygen.

Plants get hydrogen and oxygen from water in the soil, they also get carbon & oxygen from carbon dioxide and oxygen in the atmosphere. Water & carbon dioxide are used to synthesise food during photosynthesis. Oxygen is used to release energy from food during respiration.

Plants need a number of minerals for healthy growth. These are absorbed through the roots as mineral ions dissolved in the soil water.If a plant is defficent in a mineral ion it's growth will be poor. Two Mineral Ions needed:

Blue - What the mineral ion is used for. Purple - Defficency Symptoms.

Nitrate - for making amino acids which are needed to make protein. It will suffer from stunted growth.

Magnesium - for making chlorophyll. It's leaves will turn Yellow

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Green plants absorb light energy using chlorophyll in their leaves. They use it to react carbon dioxide with water to make a sugar called glucose. The glucose is used in respiration, or converted into starch and stored. Oxygen is produced as a by-product.

Temperature, carbon dioxide concentration and light intensity are factors that can limit the rate of photosynthesis.

Plants also need mineral ions, including nitrate and magnesium, for healthy growth. They suffer from poor growth in conditions where mineral ions are deficient.


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Photosynthesis Limiting Factors

Without enough light, a plant cannot photosynthesise very quickly, even if there is plenty of water and carbon dioxide. Increasing the light intensity will boost the speed of photosynthesis.

Sometimes photosynthesis is limited by the concentration of carbon dioxide in the air. Even if there is plenty of light, a plant cannot photosynthesise if there is insufficient carbon dioxide.

If it gets too cold, the rate of photosynthesis will decrease. Plants cannot photosynthesise if it is too hot/cold.

Maximising Growth - Farmers can use their knowledge of these limiting factors to increase crop growth in greenhouses. They may use artificial light so that photosynthesis can continue beyond daylight hours, or in a higher-than-normal light intensity. The use of paraffin lamps inside a greenhouse increases the rate of photosynthesis because the burning paraffin produces carbon dioxide, and heat too.

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ARTERIES : take blood from the heart around the body & have thick outer walls, thick layer of muscle and elastic fibres to withstand high pressure of oxygenated blood created by pumping heart

VEINS: bring deoxygenated blood back to the heart & have thin walls and thin layer of muscle and elastic fibres allowing the vein to be squashed when you move-pushing blood back to heart. Have valves to prevent backflow of blood

CAPILLARIES: one cell thick, allows diffusion of oxygen and food into cells and waste out of cells.

blood travels around the body through the above ^ blood vessels.

How blood circulates?
Blood from body -> right atrium--> flows into lower right ventricle--> pumps blood up to lungs to pick up oxygen --> (oxygenated)blood flows back down to left atrium --> flows into left ventricle--> pumped around body delivering oxygen to cells for respiration.
heart is like a double pump because blood passes through twice in each circuit.

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Heart Disease

Heart disease:
plaque builds up in arteries narrowing the lumen of the arteries. This restricts the flow of blood to the heart meaning Heart attacks occur because the heart's muscle cells aren't getting any oxygen or glucose to respire and therefore dying. If arteries are clogged with fat the heart has to pump harder to push blood around the body. You can measure you're blood pressure to see how hard the heart is working.

Causes of Heart disease... ? lifestyle factors

  • diet - saturated fat diets can cause this plaque to build up in arteries
  • stress
  • smoking (narrows arteries)
  • too much alcohol
  • not enough exercise ((burns fat and strengthens heart muscle)
  • genes
  • age
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How organisms develop from a single cell 1

Cell Specialization; A zygote is a structure that forms when a sperm fertilises an egg. The Zygote then divides many times by mitosis to form an embryo. The 1st division of the zygote forms 2 cells, then 4, 8 so on. Up to the 8-cell stage all of the cells are identical. It's possible for embryonic stem cells to develop into any other specialized type of cell that the growing embryo needs- for eg nerve cells, blood cells & muscle cells. But once the embryonic stem cells become specialised they can't change into any other type of cell. The specialised cells can form all the different type of tissue that the embryo needs.

Switching gene's off and on; Cells become specialised because the genes that are not needed are switched off. Only the gene's needed to make a specific type of cell work are switched on eg muscle cells only have the gene's needed to make muscle cell proteins switched on. All the other gene's eg those needed to make blood cell proteins & nerve cell proteins are switched off. (

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How organisms develop from a single cell 2

Cell Specialization in Plants: Unspecialised stem cells also exist in plants. They can become specialised into the cell of roots, leaves or flowers. Unlike animal cells, some plant cells can remain unspecialised and develop into any type of plant cell.

Meristems: Plants cells differ to animal cells by another way, unspecialised stem cells in plants are grouped together in structures called meristems. Cells produced by meristems ensure that plants continue to grow in height and width throughout their life. Plant meristems divide to produce cells that increase the height of the plant, length of the roots & girth of the stem. They also produce cells that develop into leaves & flowers.

Phototropism: Is a plant's growth response to light. When the stem grows towards the light, the plant can photosynthesis more. More food is produced so the plant can grow faster. This increases the plant's chances of survival.

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Red Blood Cells

Red Blood Cells:

-more numerous than other types

-number count increases in high altitdudes

-picks up oxygen in alveoli and tansports to respiring tissues

-biconcave disc shape = larger surface area = more oxygen diffusing

-no nuclues = more space to carry oxygen

-lots of haemoglobin:

  • picks up and reacts with oxygen = oxyhaemoglobin (brighter in colour)
  • splits to release oxygen at tissues
  • contains iron, less iron in diet = less red blood cells = anaemia
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  • Blood looks red, but up close it is cells floating in a pale yellow, watery liquid called plasma.
  • Plasma is mainly water and carries dissolved materials such as food molecules, hormones and waste products from cells. Plasma helps to pass heat around the body.
  • There are 3 types of cell that float in plasma;
  • Red Blood Cells - to transport oxygen
  • White Blood Cells - to fight infection
  • Platelets - clot blood at an injury site
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  • Platelets are fragments of cells made up from the cytoplasm of larger cells.
  • When you cut yourself, platelets stick to the outside of he cut and clot your blood, preventing you from losing to much blood.
  • If you suffer a big loss of blood then you will need a blood transfusion.
  • Bags of blood have an anticoagulent in them to stop them from clotting up in the bag.
  • It is important that the bags have the blood type clearly printed on the front to prevent problems.
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White Blood Cells

  • White blood cells protect the body by fighting infection (sometimes known as nurse cells).
  • To destroy infections they produce antibodies and then engulf and digest the microorganism in a process called phagocytosis.
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Digestive System

Mouth - grinds up the food

Oesophagus - connects the mouth to the stomach

Stomach - adds acid to the food to break it down

Duodenum - connects the stomach to the small intestine

Liver - makes bile to break down fats

Small Intestine - absorbs nutrients into the bloodstream for transport around the body

Large Intestine - recovers water from the digested food

Rectum - waste is stored here, ready to leave the body

Anus - waste leaves the body

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Functional Foods

Functional foods contain ingredients that contribute to your body's well-being.

We all carry 1KG of bacteria in our gut, some good some bad. Most of the time, the good and bad bacteria are balanced. Good bacteria suppresses the activity of the bad.

Things like stress, poor diet, and food poisoning can disturb the balance of bacteria in our gut.

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Prebiotics and Probiotics

  • Prebiotics and Probiotics boost the numbers of good bacteria over the bad
  • Prebiotics contain sugers called OLIGOSACCHARIDES which feeds the good bacteria, causing them to increase in numbers.
  • Probiotics contain the good bacteria themselves, also causing them to increase in numbers in the gut. Probiotics are produced by fermentation of milk and other foods. Prebiotics are not produced by fermentation.
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Stanol Ester

  • Stanol Ester comes from plant sterols- fatty substances found naturally in foods like wheat and maize.
  • Studies show that if a person includes plant sterols in their diet might experience their cholesterol falling by 10% in a year!
  • Benecol is an example of a functional food that contains stanol ester.
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