Biology-Organisms Exchange Substances

What do insects use to respire?

Spiracles, Trachea, Tracheoles

What do spiracles do?

Spiracles are small holes in the exoskeleton of insects which allow air to enter the insect.

What prevents water loss in insects?

Exoskeleton is waterproof.

What is the role of trachea?

Move gases into smaller tubes called tracheoles

What are tracheoles?

Small, thin tubes that are permeable, go into individual cells and tissue, allowing gases to diffuse out.

Movement of oxygen in an insect:

Oxygen moves from spiracles to trachea, travels down concentration gradient, reaches cells and tissue via tracheoles and diffuses directly into them.

Movement of Carbon Dioxide:

Diffuses down concentration gradient out of spiracles.

How does air move in/out of spiracles

Rhythmic abdominal contractions to move air into and out of spiracles

How do insects prevent water loss?

Waterproof waxy cuticles

Hairs around spiracles

Close spiracles with muscle contraction

Movement of water in a fish

Counter current- enter through mouth and moves over the gills

Structure of Fish gills

Gill filaments provide large surface area

gill filaments are covered in lamellae greater surface area

lamellae have many capillaries for rich blood supply to maintain conc gradient

Counter Current principle

Blood and water flow in opposite directions over the gills.

Blood has low Oxygen concentration

Why is counter current important

Maintains concentration gradient for efficient diffusion

Why does O2 move from water to blood

Water has high water concentration, blood has low concentration, moves from area of high to low concentration

Why do plants need for carbon dioxide?

Carbon dioxide needed for photosynthesis and respiration, release oxygen

Main gas exchange surface in a leaf?

Surface of leave-Mesophyll cells as they have a large surface area

How do gases enter/exit plant?

Diffusion through stomata.

How do stomata function?

Allow gas exchange to take place.

Close to control water loss

Guard cells control opening and closing

How do guard cells open and close?

Water enters guard cells via osmosis, makes them turgid, causes them to swell and open, opposite happens for closing.

What is a xerophyte?

A plant adapted for dry living conditions, where high water loss occurs.

5 Xerophytic adaptations:

• Stomate in pits, epidermal hairs, curled leaves, less stomate, waterproof waxy cuticles

Purpose of stomata in sunken pits?

Traps moist air, decreases concentration gradient, reduces water loss via diffusion.

Purpose of epidermal hairs?

Trap moist air around stomata, decreases concentration gradient, reduces water loss via diffusion.

Purpose of curled leaves?

Traps moist air.

Protects against wind, decreases concentration gradient, less water lost via diffusion.

Purpose of less stomata?

Less stomata so less water loss can occur at once.

Purpose of waterproof waxy cuticles?

Reduce water loss via evaporation

Structure of human gas exchange structure:

Trachea-Bronchi-Bronchus-Bronchiole-Alveoli

Alveolar Epithelium

Thin flat cells, one cell thick surrounds alveoli

How is alveoli adapted for efficient gas exchange

One cell thick, Rich supply of blood, Large surface area, ventilated

Movement of oxygen in alevoli:

Diffuses from alveoli across alveolar epithelium and capillary endothelium down a concentration gradient and diffuses into hemoglobin in blood.

Movement of Carbon dioxide in epithelium

Diffuses into alveoli from blood and is exhaled out.

Describe inspiration (inhalation)

External intercostal muscles and Diaphragm contract

Ribs move up and out Diaphragm flattens

Volume increase, pressure decreases

Air moves down a pressure gradient into lungs

Describe expiration (Exhaling)

Internal intercostal muscle contract, Diaphragm relaxes

Ribs move down and in, Diaphragm arches

Volume decreases, pressure increases

Air moves down a pressure gradient out of lungs

How would you describe the pair of internal and external intercostal muscles?

Antagonistic muscles

What happens to biological molecules during digestion?

Larger biological molecules are broken down into smaller biological molecules.

What does amylase do?

Hydrolyses glyosidic bonds in starch to produce maltose

Where is amylase produced/released?

Produced: salivary glands

Released in mouth

Produced: Pancreas

Released in small intestines

What are membrane bound disaccharides?

enzymes attached to cell membrane of epithelial cells

break disaccharides into monosaccharides

Hydrolyses glyosidic bonds

what is lipase?

Hydrolyses ester bonds in lipids to produce monoglycerides and fatty acids

Where are lipases produced/released

Produced in pancreas and released in small intestine

Where are bile salts made?

Liver

Function of bile salts?

Emulsify lipids, form small droplets, increase surface area so lipase can act faster

What happens to broken down lipases?

Monoglycerides and fatty acids stick with bile salts to form micelles.

What are endopeptidases?

Enzymes that act on central regions of polypeptide, breaking it down into smaller polypeptides.

Examples of endopeptidases:

Trypsin and chymotrypsin are two examples of endopeptidases.
They are made in the pancreas and released into the small intestine.
Pepsin is another endopeptidase. It is made in cells in the stomach lining and released into the stomach.

How do we know optimum conditions of pepsin, what are they?

Optimum conditions are acidic as pepsin is found in stomach, has a low pH

What is an exopeptidase?

Enzymes that act on the ends of polypeptides, remove singular amino acids

What are dipeptidases?

Enzymes that break down a dipeptide into two singular amino acids

Where are dipeptidases found?

Cell surface membrane of epithelial cells in small intestine.

How are amino acids absorbed in small intestine?

Co transport via sodium potassium pump

Absorption of different monosaccharides:

Glucose and amino acids absorbed by co transport

Fructose absorbed via facilitated diffusion

What are micelles made up of?

Bile salts, fatty acids and monoglycerides

Why are micelles needed?

Make fatty acids and monoglycerides more soluble in water.

Bring fatty acids and monoglycerides to cells that line ileum, maintaining concentration gradient.

How are fatty acids and monoglycerides absorbed into lining of ileum

Fatty acids and monoglycerides are absorbed by cells lining the ileum of mammals by diffusion.

What happens after the absorption of fatty acids and monoglycerides?

Triglycerides are reformed. Vesicles move to cell membrane and move them out.

What is Haemoglobin?

Group of chemically similar molecules found in many organisms.

Structure of haemoglobin?

Each chain has a haem group which has iron ion, gives haemoglobing its red colour

Four polypeptide chains make up one spherical haemoglobin

It has a quaternary structure

Why can haemoglobin carry 4 oxygen molecules?

Each chain has an iron ion which can bind to one oxygen.

There are four chains so 4 iron ions so can carry 4 oxygen molecules.

Word equation for oxygen and haemoglobin in lungs:

haemoglobin + oxygen ⇌ oxyhaemoglobin

How does affinity of haemoglobin change depending on partial pressure?

At high partial pressure of oxygen, affinity increases. Oxygen easily loads onto haemoglobin to form OXYHAEMOGLOBIN.

At low partial pressure of oxygen, affinity deacreases. Oxyhaemoglobin unloads oxygen and becomes haemoglobin.

Where is partial pressure of oxygen high/low

High in aleveoli

Low in respiring cells and muscles

What does a dissociation curve show?

How saturated haemoglobin is with oxygen at any partial pressure

What happens when haemoglobin binds with first oxygen?

Quaternary structure changes shape, making it easier for even more oxygens to bind, as another binding site was discovered.

What happens when haemoglobin is saturated?

It gets harder for oxygen molecules to bind.

How does the partial pressure of carbon dioxide affects oxygen unloading (Bohr effect).

At higher partial pressures of carbon dioxide the rate of oxygen unloading increases.
This means oxyhaemoglobin dissociates to form haemoglobin and oxygen more readily.
This is because the blood pH is lowered.

How does dissociation curve change at higher partial pressure of carbon dioxide?

Shifts to the right.

How does haemoglobin affinity of organisms living in low partial pressure compare to those living in a higher partial pressure?

Oxygen affinity for these organisms in lower partial pressure is much higher

What does circulatory system consist of?

Heart and blood vessels.,,,,,,,

What does blood transport?

Gas, waste, products of digestion, hormones and water

How does blood travel from blood to lungs to heart?

Vena cava, right atrium, right ventricle, pulmonary artery, lungs, pulmonary vein.

VRVPLV

How does blood travel from heart to kidneys to heart?

Pulmonary vein, left atrium, left ventricle, aorta, renal artery, renal vein, vena cava

How do heart muscles receive blood?

From left and right coronary arteries which branch off the aorta.

WHy is the left ventricle thicker?

Needs to contract harder to pump blood throughout the entire body

Why do ventricles have thicker walls than the atrium?

Atrium only push blood into the ventricle

Ventricles push blood throughout entire body.

What are atrioventricular valves?

Valves that prevent backflow of blood from ventricle to atrium.

What is the function of semi-lunar valves?

The semi-lunar valves link the ventricles to the pulmonary artery and aorta.
They stop blood flowing back into the heart after the ventricles contract.