UNIT 1
UNIT 2
UNIT 3
UNIT 4
SCIE 3001
Question 01 - Living Things
Question 02 - Living Things
Question 01 - Ecosystems
Question 02 - Ecosystems
Question 01 - Earth Sciences
 

Question 2 - Ecosystems

1. Leana’s class looks at a nature video and she makes the following notes:
Red mangrove trees grow in the soft sediments of the sea or brackish water along shorelines. They have poorly developed, shallow below-ground roots and prop and adventitious roots descending from the trunk and branches, providing a stable support system. Red mangroves have pores in the roots which are exposed at low tide and allow air to circulate within the root to living tissues. At high tide water fills the pores and root membranes allow the water to pass through but prevent salt from entering the cells. Thus they can thrive in areas of high soil salinities. Any excess salts are sent to sacrificial leaves which yellow, die and drop from the plant.  The leaves have a thick waxy coating which prevents excessive water loss.
Similar to many terrestrial plants, mangroves reproduce by flowering with pollination occurring via wind and insects. Once pollination occurs, the seeds remain attached to the parent tree and germinate before dropping into the waters below where they either take root in the sediments near the parent tree or are dispersed with the tides and currents to other shorelines. If the water is deep they will float horizontally, carried by the currents for upwards of a year, potentially over hundreds of kilometers.  As the root tip absorbs water, and it is pulled vertical.
Mangrove roots trap sediments, including dead leaves and other organic matter which decay to build the soil and in turn provides nutrients. As the leaves decompose, they provide food for bacteria and fungi which are eaten by conchs and crabs. Conchs and crabs also feed on the decaying leaves and are eaten by large fish. Herons feed on the conchs, crabs, shrimp and worms and are eaten by hawks.  Small fish feed on conchs, crabs, shrimp and worms and are eaten by large fish and herons. Large and small fish are eaten by fish hawks and pelicans. Grasshoppers eat living leaves of the red mangrove and are eaten by herons.
Coastlines fringed with Red Mangroves are quite stable, and protected against the ravages of erosion and storm damage.

red mangrove
red mangrove

 

(a) Describe THREE (3) ways in which the red mangrove is structurally adapted to its local environment. (6 marks)
(b) Describe THREE (3) ways in which the red mangrove is behaviorally adapted to its local environment. (6 marks)
(c)  (i) Identify and name ONE interaction which moves materials from the abiotic to biotic world in the wetland.
(ii) State how ANY ONE abiotic factor in this interaction will affect the growth and distribution of ONE named population in the wetland. (3 marks)
(d)  (i) Identify and name ONE interaction which moves materials from the biotic to abiotic world in the wetland. (ii) State how ANY ONE abiotic factor in this interaction will affect the growth and distribution of ONE named population in the wetland. (3 marks)
(e) Draw a food WEB, with all the organisms mentioned. (5 marks)

Fish hawks

Pelicans

Hawks

 

 

 

 

Large fish

Herons

 

 

 

Small fish

 

 

 

 

 

 

 

 

Crabs and Conchs

Worms and Shrimps

 

 

 

 

Bacteria
and Fungi

Grasshoppers

 

Red Mangrove

(f) Describe two ways in which the red mangrove protects the habitat. (2 marks)

Answer:
(a) Any three of the following:

i. Structure - They have prop and adventitious roots descending from the trunk and branches, Adaptation - Provides a stable support system in the soft sediments.
ii. Structure - Red mangroves have pores in the roots exposed at low tide to air
Adaptation – When exposed at low tide they allow air to circulate within the root to living tissues.
iii. Structure - Red mangroves have pores in the roots and at high tide water fills the pores and have root membranes allow the water to pass through but prevent salt from entering the cells.
Adaptation – Root membranes allow the water to pass through but prevent salt from entering the cells so it can survive in salt water (or get fresh water for photosynthesis).
iv. Structure – Excess salts are sent to sacrificial leaves which yellow, die and drop from the plant
Adaptation – Plant gets rid of salt to maintain correct salt concentration for life processes in the cells.
v. Structure – The leaves have a thick waxy coating.
Adaptation – Prevents excessive water loss in a fresh water deficient environment.
vi. Structure – Mangrove roots trap sediments, including dead leaves and other organic matter which decay to build the soil and in turn provides nutrients.
Adaptation – Plant can live in low nutrient conditions.

(b) Any three of the following:

i. Behaviour – Seeds remain attached to the parent tree and germinate before dropping into the waters below.
Adaptation – Can start growing as soon as suitable conditions are found.
ii. Behaviour – If the water is deep seeds will float horizontally, carried by the currents for upwards of a year, potentially over hundreds of kilometers.
Adaptation – Can remain dormant for more than a year after germination awaiting suitable conditions for growth.
iii. Behaviour – If the water is deep seeds will float horizontally, carried by the currents for upwards of a year, potentially over hundreds of kilometers.
Adaptation – Can remain dormant for more than a year after germination awaiting suitable conditions for growth.
iv. Behaviour – As the root tip of the germinated plant absorbs water it is pulled vertical.
Adaptation – Can orient itself when suitable growth conditions are met.


(c) (i) i. Red mangroves have pores in the roots and at high tide water fills the pores and have root membranes allow the water to pass through but prevent salt from entering the cells. Root membranes allow the water to pass through but prevent salt from entering the cells so it can move water from the abiotic to biotic by photosynthesis.
(ii) Any one of the following:

i. This is the basis for the food web and allows the red mangrove to spread to areas of ‘bare wetland’.
ii. Conchs, crabs, shrimp, worms, bacteria and fungi (only one at a time for part of the this answer) feed directly on the detritus made by and trapped by the roots of the red mangrove and so their population will increase.
iii. Grasshoppers eat living leaves of the red mangrove and so their population will increase.
iv.  small fish, large fish, hawks, fish hawks and herons (only one at a time for part of the this answer) feed indirectly on the detritus made by and trapped by the roots of the red mangrove and so their population will increase.


(d) (i) Bacteria and fungi decompose decaying matter (biotic) to return minerals to create soil (abiotic).
(ii) Any one of the following:
i. Without soil the red mangrove would not be able grow and reproduce so it could not spread to areas of ‘bare wetland’.
ii. Conchs, crabs, shrimp, worms, bacteria and fungi (only one at a time for part of the this answer) feed directly on the detritus made by and trapped by the roots of the red mangrove and so their population will increase.
iii. Grasshoppers eat living leaves of the red mangrove and so their population will increase.
iv.  small fish, large fish, hawks, fish hawks and herons (only one at a time for part of the this answer) feed indirectly on the detritus made by and trapped by the roots of the red mangrove and so their population will increase.

(e)

food web

 

(f) Any two of the following:
i. Red Mangroves are quite stable, and protected against the ravages of erosion.
ii. Red Mangroves are quite stable, and protected against the storm damage.
iii. Red Mangroves  roots trap sediment and creates soil.

Concept by Kishore Lal. Programmed by Kishore Lal... Copyright © 2015 Kishore Lal. All rights reserved.