3.3.1 Exchange Flashcards

1
Q

Describe the structure of an insects gas exchange system

A

Insects have small openings in their exoskeletons called spiracles, small tubes called tracheae divide into even smaller tubes called tracheoles. The ends of the tracheoles are filled with liquid when the insect is at rest.

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2
Q

Describe the relationship between size of organism and surface area to volume ratio

A

The larger the organism, the smaller the surface area to volume ratio

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3
Q

Explain why larger organisms need specialised gas exchange systems

A

Because they have a smaller surface area to volume ratio so can’t absorb all the gases they need by simple diffusion so they need a specialised system to provide short diffusion pathways, large surface area and maintained concentration gradients

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4
Q

Describe the structure of fish gills

A

Fish have many gill filaments, each covered in many lamellae providing a large surface area for gas exchange. The blood in the capillaries flows in the opposite direction to the water.

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5
Q

Explain why a counter-current flow more efficient than co-current flow in fish gills

A

Because the blood continues to pass water which has a higher oxygen concentration, so the concentration gradient is maintained along the whole length of the gill filament

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6
Q

How do insects limit water loss from their bodies?

A

They are covered in a water proof exoskeleton and can control the opening and closing of spiracles

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7
Q

Describe the process of gas exchange in leaves

A

Air diffuses into the stomata and into the spongy mesophylly layer where it surrounds the cells, CO2 diffuses into cells and oxygen diffuses out creating a concentration gradient between the inside and outside of the leaf, this causes CO2 to continue to diffuse into the leaf and O2 to diffuse out.

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8
Q

Explain why having hairs under leaves, rolled leaves helps a xerophytic plant to survive

A

This traps a layer of humid air near the stomata so there is a low water potential gradient between the air inside and outside of the leaf. This means that less water is lost by the plant.

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9
Q

List 4 adaptations of xerophytic plants

A

Less stomata, smaller leaves, rollled leaves, hairs under leaves, stomata in pits or grooves

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10
Q

What is tidal volume?

A

The volume of air in breathed in and out at each breath at rest

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11
Q

How do you calculate Pulmonary ventilation?

A

PV = Tidal volume x breathing rate

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12
Q

What is breathing rate?

A

Number of breaths are taken per minute

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13
Q

Describe inhalation

A

Diaphragm contracts, external intercostal muscles contract, chest volume increases, pressure in chest decreases, atmospheric pressure forces air into lungs, lungs expand to equalise pressure

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14
Q

Describe exhalation

A

Diaphragm relaxes, external intercostal muscles relax, chest volume decreases, pressure in chest decreases, air is forced out of lungs until air pressure inside and outside chest is equal

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15
Q

State two substances produced by the stomach

A

Hydrochloric Acid, protease enzymes, mucus lining

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16
Q

How is the ileum adapted to efficiently absorb nutrients?

A

It has folded inner walls (villi) with millions of microvilli providing a very large surface area. It also has membrane-bound dissacharidases, protein channels and carrier proteins on it’s epithelial cells

17
Q

Name the three major types of enzymes and where they are produced in the human digestive system

A

Proteases - stomach and pancreas (SI), Carbohydrases (Amylase) - saliva and pancreas (SI), lipases - panceas (SI)

18
Q

State the products of lipid digestion

A

Fatty acids and glycerol

19
Q

State the products of protein digestion

A

amino acids

20
Q

State the products of starch digestion

A

alpha glucose (maltose first, then alpha glucose)

21
Q

Explain how starch is digested in the human digestive system

A

Starch begins to be hydrolysed into maltose by salivary amylase, this process stops when the food reaches the stomach (amylase denatured by low pH), then pancreatic amylase continues hyrdolysing starch into maltose. When it reaches the ileum, maltose is hydrolysed into alpha glucose by membrane-bound maltase enzymes. The alpha glucose is then absorbed into the epithelial cells of the ileum lining.

22
Q

State the monosaccharides that make up sucrose

A

glucose and fructose

23
Q

State the monosaccharides that make up lactose

A

glucose and galactose

24
Q

What do the three types of peptidases do?

A

Endopeptidases hydrolyse peptide bonds in the central part of a polypeptide. Exopeptidases hydrolyse bonds at the ends (terminal amino acids), dipeptidases hydrolyse the bond between two amino acids

25
Q

Describe how lipids are digested and absorbed in the human digestive system

A

Lipids are hydrolysed by lipase and emulsified by bile salts to form micelles (monoglycerides and fatty acids in lipid droplets), micelles release monoglycerides and fatty acids at the ileum lining where they diffuse into the epithelial cell. They are immediately reformed into triglycerides by the smooth ER and packaged in protein to form chylomicrons. These are released by exocytosis into the lacteals of the lymphatic system

26
Q

label this

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