Question 1

Why do organisms need to exchange substances with their environment?

Accepted Answer

Cells need to take in oxygen and nutrients Cells need to excrete waste products (e.g. carbon dioxide and urea) Most organisms need to stay same temperature = heat needs to exchanged

Question 2

Smaller animals have a _____ SA : Volume Ratio

Accepted Answer

Higher

Question 3

Why do multicellular organisms need exchange organs and mass transport systems?

Accepted Answer

∵ diffusion across the outer membrane would be too slow

Question 4

Why don't single-celled organisms need exchange organs or mass transport systems?

Accepted Answer

∵ Substances can diffuse directly into (or out of) cells across cell-surface membrane (diffusion rate is quick)

Question 5

Name 2 things that cause diffusion across outer membrane to be too slow in multicellular organisms

Accepted Answer

Cells deep within body Big distance between them & outside environment Larger animals = low SA:volume ratio

Question 6

What is tissue fluid?

Accepted Answer

Environment around cells of multicellular organisms

Question 7

What is the mass transport system in mammals?

Accepted Answer

Circulatory system

Question 8

What is the mass transport system in plants?

Accepted Answer

Transport of water and solutes in xylem and phloem

Question 9

Name 2 factors that affect heat exchange

Accepted Answer

Shape Size

Question 10

Animals with compact shape have a ___ surface area relative to their volume which _____ heat loss from their surface

Accepted Answer

Animals with compact shape have a SMALL surface area relative to their volume which MINIMISIES heat loss from their surface

Question 11

What do small animals (with a large surface area) need to stay warm and why?

Accepted Answer

High metabolic rate to generate enough heat to stay warm ∵ they lose heat easily

Question 12

Name 3 gas exchange surfaces adaptations

Accepted Answer

Large SA Thin = short diffusion pathway Steep concentration gradient

Question 13

Name 2 ways organisms maintain a steep concentration gradient

Accepted Answer

1. Via movement of environmental medium e.g. air 2. Via transport system = ensure movement of internal medium

Question 14

Name 2 features that single-celled organisms have that allow gases to diffuse through their outer surface

Accepted Answer

Have large surface area, thin surface & short diffusion pathways

Question 15

Name the main gas exchange surface in dicotyledonous plants

Accepted Answer

Surface of mesophyll cells in leaf

Question 16

Dicotyledonous Plants Gases move in and out through special pores in epidermis called _____

Accepted Answer

stomata

Question 17

What do insects use for gas exchange?

Accepted Answer

Tracheae (microscopic air-filled pipes)

Question 18

What are spiracles?

Accepted Answer

Pores on insects' surface

Question 19

How is carbon dioxide removed from insects?

Accepted Answer

Carbon dioxide from the cells diffuses (down its own concentration gradient) into tracheal tubes and through the spiracles

Question 20

Why do insects have to be small in size?

Accepted Answer

∵ insects mainly rely on diffusion to exchange gases

Question 21

What is tracheae supported by to prevent them from collapsing?

Accepted Answer

Strengthened rings

Question 22

Name 4 adaptations of dicotyledonous plants that enable efficent gas exchange

Accepted Answer

1. Many stomata 2. Thin, flat shape = provides large SA:volume ratio 3. Numerous interconnection air spaces throughout mesophyll 4. Leaf is flattened so no living cell is far form external air

Question 23

Exchanging gases ____ water

Accepted Answer

loses

Question 24

Name 2 adaptations that insects have to minimise water loss (without reducing gas exchange too much)

Accepted Answer

If insects are losing too much water = close their spiracles using muscles Have waterproof, waxy cuticle over their body & tiny hair around their spiracles = reduce evaporation

Question 25

Name an adaptation of dicotyledonous plants to minimise water loss without reducing gas exchange too much

Accepted Answer

If plants gets dehydrated = guard cells lose water & become flaccid = closes stomata

Question 26

How are plants' stomata kept open during day (for gaseous exchange)?

Accepted Answer

Water enters guard cells = making them turgid = opens stomatal pore

Question 27

What type of process is inspiration (breathing in)?

Accepted Answer

Active process – uses energy

Question 28

What type of process is expiration (breathing out)?

Accepted Answer

Passive process

Question 29

Describe what happens during forced expiration (e.g. when you want to blow out candles)

Accepted Answer

1. External intercostal muscles relax & internal intercostal muscles contract = pulling ribcage further down and in 2. During this time, movement of 2 sets of intercostal muscles is said to be antagonistic (opposing)

Question 30

What mainly causes the air to be forced out during normal quiet breathing (e.g. sleeping)?

Accepted Answer

Recoil of the elastic lungs

Question 31

Oxygen from the air moves down the trachea, bronchi and bronchioles into the alveoli down a ______ _______

Accepted Answer

pressure gradient

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3.1.5 Gas Exchange and the Transport of Oxygen in Living Organisms Flashcards

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