21/11/2017 21/11/2017

Organisation AQA Biology topic 2

2.1 – Principles of Organisation 21/11/2017

21/11/2017 Cells, tissues, organs and systems Basically, all living things are made up of cells…

A group of CELLS makes up a TISSUE

A group of TISSUES makes up an ORGAN

A group of ORGANS makes up a SYSTEM

A group of SYSTEMS make up an ORGANISM

21/11/2017

Another example Here’s another example in humans:

Muscle cells

Muscle tissue

Organ

System

Organism

2.2 – Animal tissues, organs and organ systems

21/11/2017

21/11/2017

Recap of The Digestive System Match these functions with the parts of the digestive system that do them…

In here the food is chewed to start breaking it down. An

enzyme (amylase) is also added. This tube uses muscle contractions to push the food down

This organ mixes the food with

hydrochloric acid to kill bacteria and also produces enzymes

More enzymes are made here

Bile is produced here

Bile is stored here

Excess water is absorbed here

Food is absorbed into the bloodstream here

The digestive system is an example of an organ system in which several organs work together to digest and absorb food.

21/11/2017

Introduction to Enzymes Enzymes are biological catalysts. They help the reactions

that occur in our bodies by controlling the rate of reaction.

An enzyme is basically a large protein molecule made up of long chains of amino acids. These molecules are then “folded” to create a certain shape.

The enzyme’s shape helps another molecule “fit” into it (“lock and key”):

This shape can be destroyed (“denatured”) by high temperatures or the wrong pH:

Enzyme Substrate

21/11/2017

The “Active Site”

Enzyme Substrate

Active site

21/11/2017

Enzymes are denatured

beyond 40OC

Enzymes

Enzymes work best in certain conditions:

Enzyme activity

Temp pH pH 400C

Could be protease (found in the stomach)

Could be amylase (found in the intestine)

Notice that most enzymes are denatured at high temperatures. Different enzymes work best in different pH conditions.

Quiz on the last few slides on Enzymes 21/11/2017

1) What are enzymes?

2) What do they do in your body? What is their basic function?

3) What are enzymes made up of?

4) What term describes the way an enzyme “fits” a specific substrate?

5) What temperature do bodily enzymes often work quickest at?

6) What happens to an enzyme if it gets too hot?

7) What approximate pH range would you want an enzyme in your stomach to work best at?

8) Name 3 places in your digestive system that enzymes are produced in.

21/11/2017

The Digestive System What’s the point of the digestive system?

The whole point of digestion is to break down our food into small molecules which the body can then use to make carbohydrates, lipids and proteins. Here’s how enzymes are involved:

21/11/2017

Enzymes in digestion Enzymes can be produced by the body to help _______. When they come into contact and react with food they break it down into ______ pieces which can then pass into the ______:

Amylase (produced in the mouth, pancreas and small intestine) breaks _______ (a carbohydrate) down into glucose:

Protease (produced in the stomach, pancreas and small intestine) breaks _______ down into amino acids:

Lipase (produced in the pancreas and small intestine) breaks fats (_____) down into fatty acids and glycerol:

Words – blood, lipids, proteins, digestion, starch, smaller

Blo

odst

ream

21/11/2017

Bile and The Liver Bile is a chemical produced in the

liver and stored in the gall bladder. It has 2 functions:

1) It neutralises stomach acid and produces alkaline conditions for enzymes to work in

2) It emulsifies (“breaks down” fats:

Fat globules

Fat droplets

The alkaline conditions and large surface area of the droplets means that fats are broken down by

lipase much quicker.

21/11/2017

The Respiratory System

21/11/2017

Diffusion in the lungs Oxygen diffuses in and carbon dioxide diffuses out of blood in the lungs:

O2

CO2

Alveoli have three things that help them to do this job: a massive surface area, a moist lining that is only one cell thick and a very good blood supply.

21/11/2017

The Circulatory system The circulatory system is responsible for pumping ______ around the body. We need blood to be taken around the body because blood contains ________ and _______. These are needed so that all the ____ in our bodies can produce _____ through _________.

The main organs in the circulatory system are the _____, the lungs and the kidneys.

Words – energy, heart, blood, glucose, respiration, oxygen, cells

21/11/2017

“Double Circulation” 1) Blood gets pumped from the right ventricle in the heart to the lungs and picks up oxygen.

2) The blood is then taken back to the heart…

3) The left ventricle of the heart then pumps the blood to the intestine (where oxygen and glucose are removed)...

4) … and to the rest of the body (where oxygen is also removed)

5) After the oxygen and glucose have been removed for respiration the blood is sent back to the heart and starts again

21/11/2017

The Heart (in more detail) 1. Deoxygenated blood (i.e. blood without oxygen) enters through the vena cava into the right atrium

2. It’s then pumped through the tricuspid valve into the right ventricle

3. It’s then pumped through a valve up to the lungs through the pulmonary artery

4. Oxygenated blood from the lungs enters through the pulmonary vein into the left atrium

5. It’s then pumped through a valve into the left ventricle

6. It’s then pumped out of the aorta to the rest of the body

21/11/2017

Heart rate and Pacemakers The heart beat is normally controlled by a group of _____ on the _____ hand side of the heart called the “pacemaker”. These cells control the heart rate by producing small ______ impulses that cause the heart to _______.

If the pacemaker fails, an _______ pacemaker can be fitted.

Words – artificial, right, cells, electrical, contract

21/11/2017

Arteries, veins and capillaries Arteries carry high pressure blood away from the heart.

They have smaller lumen and no valves.

Veins carry low pressure blood back to the heart. They have thinner, less elastic walls and

have valves to prevent backflow of blood.

Capillaries have thin walls (one cell thick) to allow

glucose and oxygen to pass through. Also used to

connect arteries to veins.

“Lumen”

21/11/2017

The four parts of blood 1. RED BLOOD CELLS – contain haemoglobin and carry ______ around the body. They have no _______ and a large surface area.

2. PLATELETS – small bits of cells that lie around waiting for a cut to happen so that they can ____ (for a scab).

3. WHITE BLOOD CELLS – these help the body fight _________.

These three are all carried around by the PLASMA (a straw-coloured liquid). Plasma transports CO2 and ______ as well as taking away waste products to the ______.

Words – clot, kidneys, oxygen, nucleus, glucose, infection

21/11/2017

Heart disease

Drugs called “statins” can be used to reduce cholesterol levels and slow down the build up of fatty material.

In coronary heart disease layers of fatty material build up. What affect does this have on the heart?

21/11/2017

Heart disease Arteries can narrow due to cholesterol and other factors.

If this happens a “stent” may be needed:

21/11/2017

Mending the Heart What are the pros and cons of using the following artificial products?

Health Who is the most healthy?

Health is “the state of physical and mental well being”. How do these

people’s lifestyles promote health?

21/11/2017

How Diseases can Interact Diseases can interact with each other when they affect the body. Here are some examples:

Viruses in living cells can be a trigger for cancer.

Defects in the immune system mean that a person can catch an infectious disease more easily.

Immune reactions (after being caused by a pathogen) can cause allergies such as skin rashes

Severe physical ill health can lead to depression and other mental illnesses

21/11/2017

Interpreting Data about Health

% obesity in the UK

What does this graph tell you?

More examples of data 21/11/2017

What conclusions (for 3 marks) can you draw from these statistics?

Q1) Q2)

Source – Public Health England Source – Cancer Research UK

Non-communicable diseases 21/11/2017

“Non-communicable diseases” are ones that can’t be caught or transmitted. They can be caused by things like organ failure or poor diets.

What can cause the following diseases or conditions? Match the disease to the risk factor.

1) Heart disease

2) Cancer

3) Diabetes

4) Liver failure

5) Lung cancer

6) Premature birth

Too much alcohol

The presence of carcinogens

Poor diet and lack of exercise

Obesity

Smoking and alcohol

Smoking

Cancer 21/11/2017

It is estimated that one in three people will develop cancer of some form during their lifetime. What is it?

Benign tumours and malignant tumours can result from uncontrolled cell division. Malignant tumours are cancer – they invade neighbouring cells and spread to other parts of the body where they form secondary tumours.

What causes cancer? The following are “risk factors”: 1) Genetic factors 2) Smoking 3) Obesity 4) UV exposure

2.3 – Plant Tissues, Organs and Systems

21/11/2017

21/11/2017

Examples of Plant Tissue 1) Epidermal tissue, which covers the plant

2) Palisade mesophyll, where photosynthesis occurs

4) Xylem and phloem, which are used to transport substances around the plant

3) Spongy mesophyll, where gases move through air spaces

5) Meristem tissue found at the growing tips of shoots and roots

21/11/2017

Large surface area

Thin structure

Network of veins

Lots of chlorophyll

Cross section of a leaf

Transparent

Packed with chloroplasts

Lots of air spaces

Guard cells and holes

21/11/2017 Plant organs and transporting substances

A group of CELLS makes up a TISSUE

A group of TISSUES makes up an ORGAN, in this case, a leaf

A group of ORGANS makes up a SYSTEM. In a plant, the roots, stem and leaves form a system

that is used to transport substances around the plant.

21/11/2017

Transpiration 1) Water evaporates through the stomata

2) Water passes back into the leaf through xylem vessels by osmosis

3) Water is then pulled upwards through the xylem tissue

4) This is replaced by water entering from the root tissue

5) Water enters root hair cells by osmosis to eventually replace the water lost through respiration

21/11/2017

Transpiration Rate What factors would cause transpiration to happen the quickest?

1) Temperature – what temperature do you think transpiration is quickest at?

2) Humidity – is transpiration quicker when it is more or less humid?

3) Air flow – how does this affect transpiration?

4) Light intensity – how would this affect transpiration?

21/11/2017

Xylem and Phloem Xylem are used by the plant to transport ____ and soluble mineral ______ from the roots to the stem and the leaves. Xylem are hollow ______ strengthened by lignin.

Phloem are tubes used by the plant to transport dissolved ______ to the whole plant for _______ and storage. The movement of food through phloem is called _______ . Phloem is composed of tubes of elongated cells where cell sap can move from one phloem cell to the next through ____ in the end walls.

Words – tubes, translocation, salts, water, sugars, respiration, pores

21/11/2017

Plant roots are made of “root hair cells” which have two features that help them to take in water and nutrients (“active uptake”):

Root hair cells

Root hair cells

Thin cell membrane Large surface area

21/11/2017

Guard Cells and Stomata

The roles of guard cells and stomata are to control gas exchange and water loss.