Organisms Exchange Substances With Their Environment 3

Question 1

Define digestion

Answer 1

The hydrolysis of large Insoluble food molecules into small soluble food molecules that can be absorbed and assimilated

Question 2

What is the surface area to volume ratio like for smaller organisms and larger organisms

Answer 2

Smaller organisms have a large surface area to volume ratio
Larger organisms have a smaller surface area to volume ratio

Question 3

What are the features of small organisms that allows them to simply exchange substances across their surface

Answer 3

Big surface area for susbyabce exchange
Short diffusion distance from the outside to the centre of the organisms

Question 4

What features does large organisms have which means substances can’t diffuse across the surface

Answer 4

Smaller surface area to volume ratio and a larger distance from tbe outside to the centre of the organism
Larger organisms usually have a higher metabolic rate so it requires more efficient transport of waste out of cells and reactants into the cell(oxygen, carbon dioxide, nutrients, urea, amino acids)

Question 5

What are some evolved features for efficient Gas exchange

Answer 5

-Flattened shape(No cell is far from the surface e.g. flatwork, leaf)
-Specialised exchange surface(Increase surface area to volume ratio e.g. lungs gills)

Question 6

What are some key features of specialised exchange surfaces

Answer 6

-Large surface area to volume ratio
-Very thin membranes(short diffusion distance)
-Movement of environmental medium
-Transport system(movement of internal medium to maintain a diffusion system)
-Partially permeable so only specific molecules can pass through

Question 7

Explain the process of digestion of carbohydrates/polysaccharides

Answer 7

Salivary glands and pancreas produce amylase which hydrolyses polysaccharides into disaccharides by hydrolysis glycosidic bonds
In the duodenum and iluem, membrane bound disacchardases are produced which hydrolysis disaccharides into monosaccharides

Question 8

What are the two types of digestion and explain them

Answer 8

Mechanical: Hydrolysis of large food molecules into smaller forms to increase surface area
Chemical: Hydrolysis of large food moelcules into smaller soluble molecules with the action of enzymes

Question 9

What does Maltase, sucrase and lactase do

Answer 9

Maltase hydrolyses Maltose into glucose
Sucrase hydrolyses sucrose into glucose and fructose
Lactase hydrolyses lactose unto glucose and fructose

Question 10

What is the oesophagus
Peristalsis pushes food down into the stomach, what is peristalsis

Answer 10

A muscular tube that connects the mouth to the stomach
The contraction and relaxation of the walls of the oesophagus

Question 11

What happens to carbohydrates in the stomach

Answer 11

Nothing because there’s no amylase, only churning of carbohydrates

Question 12

How is the ileum adapted to absorption
Why is pancreatic juice alkali

Answer 12

Inner walls are folded into villi which are further folded into microvilli which increases surface area for absoption
To maintain a neutral pH as food from the stomach is acidic brcuqse it contains HCL

Question 13

Starch is hydrolysed into — which is then hydrolysed into —-

Answer 13

Maltose
Glucose

Question 14

What is absorption

Answer 14

Digested food molecules cross the walls of the intestine into the blood

Question 15

How is the small intestine adapted to increase absorption rates

Answer 15

-Lots of microvilli(projections on the surface of intestines) which increases surface area
-Lots of mitochondria which releases ATP

Question 16

What are cotransport proteins

Answer 16

Proteins that transport two or more moelcules across a membrane

Question 17

What are peptidases

Answer 17

Enzymes involved in the hydrolysis of proteins by hydrolysing peptide bonds between amino acids

Question 18

Explain how peptin,endopeptidases, exopeptidases and dipeptidases are involved in the digestion of proteins

Answer 18

PEPTIN: Hydrolyses proteins into peptides
ENDOPEPTIDASES: Hydrolyses peptide bonds between amino acids in the central region of the protein to form smaller peptide moelcules+increase surface area
EXOPEPTIDASES: Hydrolyses peptide bonds on the terminal amino acids of a peptide
DIPEPTIDASES: Hydrolyses peptide bonds between amino acids in a dipeptide

Question 19

Where is carbohydrase, lipase and protease produced

Answer 19

CARBOHYDRASE: Pancreas, Small intestines, Salivary glands
LIPASE: Pancreas, Small intestines
PROTEASE: Pancreas, Small intestines, stomach

Question 20

What is beneficial about the function of endopeptidases

Answer 20

They make more ends for exopeptidases to act on and also increase the surface area

Question 21

What are lipids digested by

Answer 21

Lipase and bile salts

Question 22

Explain the process of lipid digestion and absorption

Answer 22

-Lipase is produced in the pancreas which hydrolyses ester bonds in triglycerides to form monoglycerides and fatty acids
-Bile acid emulsifies large globules of fat into smaller droplets to increase surface area for faster hydrolysis by lipase
-Bile salts, monoglycerides and fatty acids combine to make micelles which makes fatty acids and monoglycerides more soluble in water
-Micelles carry fatty acids and monoglycerides to the epithelial cells through diffusion as they are non polar
-Fatty acids and monoglycerides join to form triglycerides
-Golgi apparatus packages triglycerides and proteins to form a chylomicron
-Excocytosis occurs which releases the chylomicron from the epithelial cells into the lacteal
-The lacteal takes the chylomicron to the blood capillaries

Question 23

EXAM QUESTION: Describe the processes involved in the absorption and transport of digested lipid moelciles from the ileum to lymph vessels(5 marks)

Answer 23

1. Micelles contain bile salts, fatty acids and monoglycerides
2. Makes fattya cider and monoglycerides more soluble in water
3. Fatty acids and monoglycerides absorbed by diffusion
4. Triglycerides are formed
5. Excocytosis

Question 24

Insects have a thick exoskeleton
Describe the exoskeleton

Answer 24

It is made from a hard fibrous material for protection and a lipid layer to prevent water loss from evaporation of surfaces

Question 25

Insects don’t have lungs, instead they have a …

Answer 25

Tracheal system

Question 26

What are 3 insects adaptations to prevent water loss

Answer 26

-Insects gave a small surface area to volume ratio where water can evapourate from
-Insects have a waterproof exoskeleton
-Pair of valves over spiracles which can open and close to reduce water loss

Question 27

Explain Spiracles
Explain Trachea
Explain Tracheoles

Answer 27

SPIRACLES: Holes in exoskeleton, Pair of valves over spriracles which can open and close, hairs around valve to reduce water loss
TRACHEA: Network of tubes with rings of chitin in it which strengthens the tubes and keeps them open
TRACHEOLES: Dead end tubes(made of dead cells), end at body cells (to deliver oxygen to all repairing cells), contains air sacs(gas is stored), (larger insects) filled with water

Question 28

Explain how oxygen is transported in the tracheal system of an insect

Answer 28

During respiration, oxygen is used up so the oxygen cocnetrarion at tracheole ends decreases so there is now a cocnetrarion gradient for oxygen so oxygen diffuses down the cocnetrarion gradient from the atmosphere, along he trachea and tracheoles into the cell

Question 29

Explain how carbon dioxide is transported in the tracheal system of an insect

Answer 29

During respiration, carbon dioxide is produced so the carbon dioxide concentration at tracheole ends decreases so now there is a concentration gradient for carbon dioxide so carbon dioxide diffuses down the cocnnetrarion gradient from cells, along tracheoles and trachea, into the atmosphere

Question 30

What are the advantages and disadvantages of the tracheal system in insects

Answer 30

ADVANTAGES: Short diffusion pathway for gases, maintains diffusion concentration gradient
DISADVANTAGES: When spiracle valves open water can evaporates which causes dehydration (this can be overcome as spiracles remain closed most of the times as air stored in air sacs can be used), relies on diffusion so diffusion pathway has to be short so the size of the insect is limited

Question 31

Why is the tracheal system insufficient for larger insects

Answer 31

-Diffusion pathway is longer
-More active so needs more energy
-Needs more oxygen

Question 32

Describe two methods large insects use for the movement of gases

Answer 32

-Rings of muscles that can contract or relax (rhythmic abdominal movement) which allows a large movement of air in and out of the trachea which increases the concentration gradient
-Muscle cells carry out anaerobic respiration which produces lactate, water potential in muscles decreases, water moelcules osmosis from the tracheoles into muscle cells, this increases the exposed surface area for air, gases diffuse faster in air than water so a greater volume of oxygen is supplied(goes back to aerobic respiration)

Question 33

Give 3 adaptations in insects for efficient Gas exchange

Answer 33

-Large number of fine tracheoles which gives a larger surface area
-Walls of tracheoles are thin and short distance between spiracles and tracheoles
-Use of oxygen and production of carbon dioxide creates steep diffusion gradients

Question 34

What are two features of bony fish

Answer 34

Waterproof scales and small surface area to volume ratio

Question 35

Gills are made from … that are …..
Each Gill filament is covered in … which are …. to the filament
As water passes through the gills, … occurs at the lamellae

Answer 35

Gills are made from Gill filaments that are stacked upon eachother
Each Gill filament is covered in lamellae which are perpendicular to the filaments
As water passes through the gills, gas exchange occurs at the lamellae

Question 36

List the adaptations for efficent gas exchange in fish

Answer 36

-Many Gill filaments covered in lamallae which increases surface area
-Single layer of epithelial cells which provides a short diffusion pathway
-Dense capillary network which provides a short diffusion pathway
-Fish pushes water over gills which means there’s constant ventilation
-Counter current flow maintains a concentration gradient

Question 37

What is counter current flow

Answer 37

The flow of blood in capillaries and water over lamellae in opposite directions

Question 38

Explain how counter current enables efficient diffusion of gases

Answer 38

It ensures that that the equilibrium is not reached as the diffusion gradient is maintained across the entire length of the lamellae so almost all of the oxygen diffuses into the blood

Question 39

Explain why parallel flow in fishes leads to inefficient diffusion of gases

Answer 39

The diffusion gradient is not maintained across the entire length of the lamella so only some of the oxygen diffuses in

Question 40

Fish Samsung notes

Answer 40

🎣🐟🐠🐡

Question 41

Define ventilation
Define respiration

Answer 41

Ventilation is the physical movement of air in and out the lungs
Respiration is the chemical reaction to release energy in the form of ATP

Question 42

Explain the structure of trachea and bronchus

Answer 42

-contains goblet cells which produces mucus that traps dirt
-made of smooth and elastic muscles which are lined with ciliated epithelium and cilia removes mucus
-flexible
-c shaped cartilage which holds it open and prevents it from collapsing

Question 43

Explain the structure and function of bronchioles

Answer 43

Made from muscle which cknstrict to control air flow

Question 44

What are alveoli made from
How is it adapted for efficient Gas exchange

Answer 44

Collagen and elastic fibres
Capillary is one cell thick and alveoli epithelium cells are very thin providing a short diffusion pathway
Alveoli surrounded by a network of capillaries which maintains a concentration gradient
Lots of alveoli with a large surface area to volume ratio which increases surface area

Question 45

Where is the thorax located
What is the diaphragm

Answer 45

Between the neck and abdomen
Dome shaped muslce that seperates thorax from abdomen

Question 46

Intercostal muscles are a ….. pair of muscles

Answer 46

Antagonistic

Question 47

Is it inspiration or expiration when external intercostal muscles contract and when internal intercostal muscles contract

Answer 47

External intercostal muscles contract - Inspiration
Internal intercostal muscles contract - Expiration

Question 48

Explain the process of inhalation

Answer 48

-External intercostal muscles contract and internal intercostal muscles relax
-Diaphragm contracts and flattens
-Volume of thorax increases as ghe ribcage moves up and out
-Pressure of thorax decreases to below atmospheric pressure
-Atmospheric air is forces into lungs down pressure gradient

Question 49

Explain the process of exhalation

Answer 49

-External intercostal muscles relax and internal intercostal muscles contracts
-Diaphragm relaxes
-Volume of thorax decreases as the ribcage moves in
-Pressure of thorax increases to above atmospheric pressure
-Air is forces out of the lungs down pressure gradient

Question 50

Define pulmonary ventilation
What is the formula for pulmonary ventilation
Give the units
Define each part in the formula

Answer 50

Pulmonary ventilation is the total volume of air that moves into lungs in one minute
Pulmonary ventilation(dm³min-¹) = Tidal volume(dm³) × Breathing rate(min-¹)
Tidal volume is the volume of air takin in at each breath
Breathing rate is the number of breaths taken in a minute

Question 51

What does a spirometer do

Answer 51

Records the volume of air in and out the lung

Question 52

Define correlation, causation and risk factors

Answer 52

CORRELATION: Change in one variable is linked to the change in another
CAUSATION: One variable directly causes another
RISK FACTORS: Something that correlates with an increased chance of developing a disease

Question 53

When do you use and what is measurements, what two tests
When do you use and what is frequencies, what test

Answer 53

MEASUREMENTS: Investigation Involved in taking measurements
-Looking for differences between mean values(t test)
-Looks for associations between different measurements from the same sample - correlation coefficient
FREQUENCIES: Finds the number of individuals in different categories(chi squared test)

Question 54

For correlation coefficient, give a conclusion for when the result of a statistical analysis is larger than the critical value

Answer 54

There is less than 5% probability that the correlation is due to chance
We reject the null hypothesis

Question 55

For correlation coefficient, give a conclusion for when the result of a statistical analysis is smaller than the critical value

Answer 55

There is more than 5% probability that the correlation is due to chance
Accept null hypothesis