TOPIC 2: Organisation 🫀🩸

What are Enzymes ?

Biological catalysts that speed up a reaction without being used up.

What is the Lock and Key theory for enzymes ?

That an enzymes active site will only fit one type of substrate , a specific shape.

What does amylase break down?

It breaks down carbohydrates into simple sugars .

What does Lipase break down ?

Breaks down lipids into fatty acids and glycerol

What does protease break down?

It breaks down proteins into amino acids

What is the mouth’s role in digestion?

Releases saliva which contains amylase to begin the breakdown of the food .

What is the role of the stomach in digestion?

• the stomach physically contracts to break down the food

• Creates protease and contains stomach acid to kill bacteria .

What is the role of the large and small intestine in the digestive system?

Small intestine absorbs the food

Large intestine absorbs the water .

What is the role of the liver in the digestive system ?

The liver produces bile which neutralises the stomach acids .

What does the bile do ?

Bile emulsifies fats, breaking them down into smaller droplets that can be more easily digested by enzymes

What substance tests for starch ?

Iodine

What colour will the solution turn if the starch is present ?

The colour will change from orange to blue/black

What solution can be used to test for sugars ?

Benedict’s solution

What colour will the solution turn if sugars are present ?

Blue to brick red

What solution tests for proteins ?

Biurets reagent

What colour will the solution turn if protein is present ?

The colour will change from blue to purple/lilac

What solution can be used to test for Lipids ?

The Sudan stain solution

What will happen to the solution if the lipids are present ?

A distinct layer will form as the layers separate

Where does gas exchange take place ?

In the alveoli

What is gas exchange ?

When oxygen is exchanged for carbon dioxide in the blood.

Describe the path of blood through the heart

• De-oxygenated blood enters the right atrium via the vena cava .

• The blood is then forced into the right ventricle . When the right ventricle contracts , the blood flows into the pulmonary artery to the lungs .

• The blood is re-oxygenated and returns to the heart via the pulmonary vein.

• The blood flows into the left ventricle ,and then is forced into the left atrium.

• When the ventricles contract ,the blood travels up the aorta and to the rest of the body,

How is the artery adapted for blood transportation

• the artery carries blood away from the heart

• Has thick muscular walls and a small lumen because it carries blood to the body at a high pressure .

Describe the structure of the vein and its function

• the vein carries the blood to the heart, at a low pressure

• Has elastic walls that are less muscular

• Has valves to prevent back flow , and has a small lumen because it carries blood at a low pressure .

Describe the structure of the capillary and its function.

• Walls are 1 cell thick to allow for a short diffusion pathway

• High density to allow for efficient gas exchange

• Permeable walls to allow for easy diffusion .

What is the role of the waxy cuticle? (plant organisation)

It reduces water loss

What is the role of the upper epidermis (plant organisation)

Transparent to let light through

What is the role of the palisade layer ? (Plant organisation)

Has lots of chloroplasts for efficient photosynthesis

What is the role of the spongy mesophyll ? (Plant organisation)

Has air spaces to allow gas exchange and permeable walls.

What is the role of the lower epidermis ? (Plant organisation)

Gaps called stomata and guard cells to allow gases in and out of the stomata .

What is the role of the xylem ? (Plant organisation)

transports water and minerals from the roots up the plant stem and into the leaves.

How is the xylem adapted for water transportation ? (Plant organisation)

• Xylem cells have no cytoplasm or end walls, meaning they form a tube through which water can pass freely to allow water transport

• Lignin strengthens the cell walls, helping to support the plant.

What is the role of the phloem (plant organisation )

moves food substances that the plant has produced by photosynthesis E.g sugars

How is phloem adapted for its function ?

• Made of living cells

• they have perforated ends so that one cell is connected to the next allowing the free flow of the cytoplasm