B3: Organisation and the digestive system and B4: Organising Animals and Plants

What is a tissue?

A group of cells with similar structure and function working together

What does muscular tissue do?

Contract to bring about movement

What does glandular tissue do?

Contains secretory cells that can produce and release substances such as enzymes and hormone

What does epithelial tissue do?

Covers the outside of our body and our internal organs

What is an organ?

A collection of tissues working together to perform a specific function

What does muscular tissue do in the stomach?

Churn the food and digestive juices of the stomach together

What does glandular tissue do in the stomach?

Produce the digestive juices that break down food

What does epithelial tissue do in the stomach?

Covers the inside and the outside of the stomach

What is an organ system?

Groups of organs that all work together to perform specific functions

Name organ systems

Digestive system, circulatory system, gas exchange system

What is the purpose of the digestive system?

To break down large insoluble molecules to form smaller, soluble molecules

What is the digestive system?

A muscular tube that squeezes your food through it. It starts at on end with your mouth and finishes at the other at your anus.

What are the glands in the digestive system and what are their functions?

The pancreas and salivary glands and they make and release digestive juices containing enzymes to break down your food

Where is food broken down in the digestive system?

The stomach and the small intestine

How is the small intestine adapted to its function?

Thin wall for quick diffusion, rich blood supply, very long (increases SA), Villi and Microvilli increase the surface area.

What are carbohydrates?

sugars and starches

What chemicals are in carbohydrates?

carbon, hydrogen, oxygen

What are simple sugars?

Carbohydrates that contain only one or two sugar units

What is the food test for carbohydrates?

iodine test for starch:
yellow/red iodine solution turns blue/black

benedict's test for sugars:
blue benedict's solution turns brick red if a sugar such as glucose is present

Name foods rich in carbohydrates

bread, potatoes, rice and pasta

What do complex carbohydrates contain?

Long chains of simple sugar units bonded together

What are lipids?

fats and oils

What are lipids used for?

long term energy storage, insulation, protection

Are lipids soluble in water?

no, insoluble

What are lipids made up of?

Three molecules of fatty acids joined to a molecule of glycerol

What is the food test for lipids?

ethanol test - ethanol added to a solution gives a cloudy white layer if a lipid is present

What are foods rich in lipids?

oils, butter, cheese, cream

What are proteins made up of?

long chains of amino acids and made up of the chemicals carbon, hydrogen, oxygen and nitrogen

What is the food test for protein?

Biuret test - blue Biuret reagent turns purple if protein is present

Name functions of protein

growth, repair, heat and energy, makes enzymes, hormones and antibodies

What is a catalyst?

substance that speeds up the rate of a chemical reaction

What are enzymes?

Large protein (biological catalyst) molecules

How do enzymes speed up chemical reactions?

An enzyme reacts with a particular substrate. The substrate of the reaction to be catalysed fits into the active site of the enzyme. Once it is in place, the substrate and the enzyme binds together. The reaction rapidly takes place and the products are then released from the surface of the enzyme.

What is metabolism?

sum of all chemical reactions in the body (or cell).

Name different ways enzymes catalyse different types of metabolic reactions

-Building large molecules from smaller ones
-Changing one molecule into another
-Breaking down large molecules into smaller ones

What is enzyme activity affected by?

temperature and pH

What happens when an enzyme is in high temperatures?

The long amino acid chains in the enzyme begins to unravel and the shape of the active site changes. Due to this, the substrate will no
longer be able to fit in the active site and the enzyme would have been denatured.

How can pH affect an enzyme?

Most enzymes 'prefer' pH values from 6-8. Optimal shape and charge at that pH. It can affect the shape of the active site of the enzyme and make it work very efficiently or stop it from working

What is starch catalysed by?

Carbohydrase such as amylase

Where is amylase produced?

Salivary glands, pancreas, small intestine

What is protein catalysed by?

Protease

Where is protease produced?

stomach, small intestine, pancreas

What are lipids catalysed by?

lipase

Where is lipase produced?

small intestine and pancreas

What does protein break down into?

amino acids

What do carbohydrates break down into?

simple sugars (glucose)

What do lipids break down into?

fatty acids and glycerol

What conditions in the stomach do protease enzymes work best in?

acid conditions

Describe how your body creates the right pH in the stomach for this enzyme

The stomach produces hydrochloric acid, which maintains a low pH

What conditions in the pancreas and small intestine do protease enzymes work best in?

alkaline conditions

What is bile used for?

Neutralises stomach acid and emulsifies fats into smaller droplets with a larger surface area

Why is a leaf an organ?

there are many tissues inside the leaf that work together to perform photosynthesis

How is the upper epidermis adapted for its function?

• single layer of transparent cells allow light to pass through
• cells secrete a waxy substance that makes leaves waterproof

How is palisade mesophyll tissue adapted for its function?

Palisade mesophyll tissue contains lots of chloroplasts which allows photosynthesis to progress at a rapid rate.

How is spongy mesophyll tissue adapted for its function?

Spongy mesophyll tissue has lots of air spaces which allow gases (including oxygen and carbon dioxide) to diffuse in and out.

What are the function of guard cells?

Control the opening and closing of the stomata

What is the function of the xylem?

transports water and soluble mineral nutrients from the roots throughout the plant

What are adaptations of the xylem?

- Elongated cells arranged end to end to form a continuous column
- Hollow due to lignification so no cytoplasm/nucleus to slow water flow
- End walls break down for flow
- Thick cell walls with lignin
- Rigid so less likely to collapse under low pressure
- Waterproof preventing water loss

What is the function of the phloem?

transports the products of photosynthesis (dissolved sugars)

What is the purpose of translocation?

transport dissolved sugars from the leaves to other parts of the plant for respiration, growth, and storage

Define transpiration

Transpiration is the loss of water vapour from the leaves and stems of plants.

What is the purpose of transpiration?

- provide water to keep cells turgid
- provide water to cells for photosynthesis
- transport mineral ions to leaves

Name 4 factors that affect the rate of transpiration

temperature, light intensity, humidity and wind speed

What effect does temperature have on the rate of transpiration?

higher temperatures increase the rate of transpiration

What effect does humidity have on the rate of transpiration?

higher levels of humidity decrease the rate of transpiration

Why does increased light intensity increase the rate of transpiration?

stomata open wider to let more carbon dioxide into the leaf for photosynthesis

What is the function of the stomata?

Allows gas exchange (carbon dioxide and oxygen) & transpiration (evaporation of water from plant into the air)

Where are most stomata found?

underside of leaves

What is the advantage to the plant of having a high number of stomata at the underside of the leaf?

reduces the amount of water loss through evaporation

What are guard cells?

cells that open and close the stomata

Name the four components of blood

red blood cells, white blood cells, plasma, platelets

What are the function of platelets?

prevent blood loss by forming a blood clot and prevent infection

Name adaptations of a red blood cell

- bi-concave disk shape- has a large surface area to volume ratio for diffusion of oxygen
- contains haemoglobin which binds to the oxygen
- no nucleus- more space for the oxygen

How do white blood cells protect the body?

• engulf pathogens
• produce antitoxins to neutralise toxins, or antibodies

Name the substances transported in the blood plasma.

hormones, proteins, urea, carbon dioxide, glucose

Why is the human circulatory system called a double circulatory system?

The human circulatory system is called a double circulatory system because blood passes through the heart twice per circuit. De-oxygenated blood is pumped from the right side of the heart to the lungs and oxygenated blood is pumped from the left side of the heart to the rest of the body

Describe the circulatory system

The vena cava brings de-oxygenated blood to the heart. The blood then passes through the right atrium and then the right ventricle which can pump the blood through the pulmonary artery which takes the de-oxygenated blood to the lungs. The pulmonary vein brings oxygenated blood from the lungs into the left atrium and then to the left ventricle which pumps blood throughout the body. The aorta carries the oxygenated blood then throughout the body.

What is the function of the artery?

carries blood away from the heart (high pressure)

What is the function of the vein?

carries blood to the heart (low pressure)

What is the function of the capillary?

carries blood to tissues and cells, connects arteries and veins.

What is the structure of an artery?

Thick muscular elastic walls that can withstand high pressure with a small lumen

What is the structure of a vein?

has valves which stop the blood going in the wrong direction, with thin walls and a large lumen

What is the structure of a capillary?

it is one wall thick so oxygen and carbon dioxide can easily pass through, has a large surface area as there as lots of them with a narrow lumen