15.1

Question 1

Diffusion is adequate for transport over ___(1)___ distances. The efficient supply of materials over ___(2)___ distances requires a __(3)__ ____(4)____ ___(5)___.

Answer 1

(1) short
(2) larger
(3) mass
(4) transport
(5) system

Question 2

All organisms need to ___(1)___ materials between themselves and their _____(2)_____. In small organisms, this exchange takes place on the ____(3)____. However, with increasing size, the surface area to volume ratio _____(4)_____ to a point where the needs of the organism ___(5)___ be met by the ____(3)____ alone. A specialist ____(1)____ ____(6)____ is therefore needed.

Answer 2

(1) Exchange
(2) environment
(3) body surface
(4) decreases
(5) can’t
(6) surface

Question 3

A transport system is required to take ____(1)____ from __(2)__ to ____(3)____ ____(4)____ and from ____(3)____ ____(4)____ to __(2)__.

Answer 3

(1) materials
(2) cells
(3) Exchange
(4) surfaces

Question 4

Whether or not there is a specialised transport medium, and whether or not it is circulated by a pump, depends on 2 factors. What are these 2 factors? (2)

Answer 4

(1) S.A. : V ratio (the lower it is, the more it needs these 2)
(2) how active the organism is (the more active, the more it needs these 2)

Question 5

Transport systems of many organisms have many common features. What are 6 of them? (6)

HINT: M, MT, V, M, MMF, CF

Answer 5

(1) A suitable MEDIUM in which to carry materials (has to be liquid based on water because 1. It readily dissolves substances 2. it can be moved around easily)
(2) a form of MASS TRANSPORT (where the medium is moved around in bulk over large distances)
(3) a closed system of tubular VESSELS that contains the medium (& forms a branching network to distribute the medium)
(4) a mechanism for MOVING the transport medium within vessels (requires pressure difference between body parts. E.g. animals=muscle contraction & plants=passive & natural processes)
(5) a mechanism to MAINTAIN the MASS FLOW movement in 1 direction (e.g. valves)
(6) a means of CONTROLLING the FLOW of the transport medium (to suit the changing needs of different parts of the organism

Question 6

Mammals have a __(1)__ blood system in which blood is ___(2)___ to vessels. A ____(3)____ pump called the heart _____(4)_____ the blood around the body. Mammals have a ____(5)____ circulatory system.

Answer 6

(1) closed
(2) confined
(3) muscular
(4) circulates
(5) double

Question 7

What does having a double circulatory system mean? (1)

Answer 7

This means that blood passes twice through the heart for each complete circuit of the body.

Question 8

Why is it advantageous to have a double circulatory system? (2)

Answer 8

(1) increases blood pressure
(2) increases rate of blood flow to tissues

Question 9

The final exchange from blood vessels into cells is rapid because it takes place over a large ____(1)____ ____ across __(2)__ distances, and there is a __(3)__ diffusion gradient.

Answer 9

(1) surface area
(2) short
(3) steep