WS 1.4

Question 1

As the amount of annual rainfall decreases,
♡ ____________________________________________
♡ ___________________________________
♡ ________________________________________
♡ ____________________________________
♡ ___________________

Answer 1

the vegetation cover changes from dense to sparse
there are fewer species of plants
there are fewer layers in vertical structure
the plants become shorter in height
there are fewer trees

Question 2

Name and describe the transitional region between the rainforest and the desert.

Answer 2

The savanna. It has little trees, grass and cactuses.

Question 3

Name the six regions that are differentiated by their annual rainfall, and their annual rainfall.

Answer 3

Tropical rainforest, over 2000mm.
Tropical forest and woodland, 1000mm-2000mm.
Savanna, 500mm-1000mm.
Semi-desert, 250-500mm.
Desert, below 250mm.

Question 4

Describe and explain the environment of tropical rainforests.

Answer 4

The hot and wet equatorial climate of tropical rainforests supports dense forests. Many different kinds of plants grow in the hot and humid environments.

Question 5

Tropical rainforest are homes of over _________________ species of the world’s plants and animals, which is _________________ of the Earth’s wildlife. There are __________________________________ (at least ______ of the Earth’s plant species) and contain __________________________________, so the tropical rainforests are said to be ________________________________.

Answer 5

30 million, over 50%, over 5000 kinds of plant species, 2/3, 1/3 of the world’s bird species, rich in biodiversity

Question 6

Explain why tropical rainforests are evergreen.

Answer 6

The hot and wet climate of tropical rainforests throughout the year favours the continuous growth of plants all year round. Fallen leaves will be quickly replaced by new ones.

Question 7

In general, the profile of a typical rainforest shows a __________________________________.

Answer 7

layered structure

Question 8

Name the five layers of a tropical rainforest.

Answer 8

Emergent layer
Canopy layer
Young tree layer / under canopy layer
Shrub layer
Ground layer / forest floor

Question 9

Name the general facts of the emergent layer.

Answer 9

Its height ranges from 50m up to 80m. It is the uppermost layer in a rainforest. The only animals found here are bats and birds such as eagles.

Question 10

Name the characteristics of the plants in the emergent layer.

Answer 10

Most of the trees found here are old trees of 50-100 years of age.
The trees here tend to have umbrella-shaped crowns so that they are fully exposed to the sun.
The trees here are widely spaced.
The trees here “emerge” from the canopy layer to reach sunlight.

Question 11

Why is it important for trees to grow tall in the tropical rainforest?

Answer 11

This is because they are in competition with other trees and plants for sunlight for photosynthesis.

Question 12

Name an example of a plant found in the emergent layer of a rainforest and describe one of its characteristics.

Answer 12

Kapok tree; they have fluffy seeds to make use of the winds to carry them away.

Question 13

Name the general facts of the canopy layer.

Answer 13

Its height ranges from 20m to 35m. The canopy layer is home to over 70% of animals in the rainforest as food is plentiful at this layer. It is the most productive part of the forest, where photosynthesis is at its greatest.

Question 14

Name the characteristics of the plants found in the canopy layer.

Answer 14

The canopy layer is a layer of dense, tall trees ranging from 20m to 35m. The trees here are oval-shaped with overlapping crowns and long branches to absorb as much sunlight as possible. This layer blocks up to 90% of the sunlight.

Question 15

Name a type of plant that can be found in the canopy layer and describe its characteristics.

Answer 15

Cauliflory. Cauliflory trees flower and fruit from their trunks so that they can attract insects, birds and animals to help them disperse their seeds.

Question 16

Name the general facts of the young tree/ under canopy layer.

Answer 16

Its height seldom exceeds 15m. This layer is dark and gloomy since the thick canopy shuts out much sunlight.

Question 17

Name the characteristics of the plants found in the young tree/ under canopy layer.

Answer 17

The plants here have much larger leaves compared to those in the upper layers.
Saplings/ young trees wait here for larger plants/ trees to die, leaving a gap in the canopy and allowing them to grow into it.
The trees here are short and widely spaced with slender trunks and oval-shaped crowns.
The interlocking spindly, flexible branches of the trees found here allows animals such as orangutans to travel around the rainforest easily.

Question 18

Name the general facts of the shrub layer.

Answer 18

Its height is less than 5m. In this layer, it is even darker as it is below the young tree layer. The relative humidity is very high and it is much cooler in here due to the constant shade. This makes it easier for plants and animals to survive here due to the abundant water supply.

Question 19

Describe the plants that can be found in the shrub layer and describe their characteristics.

Answer 19

Shade tolerant plants such as shrubs, ferns, plants with big leaves etc which do not need much sunlight can be grown in here. Plants with big leaves utilise them to absorb as much sunlight as possible.

Question 20

Name the general facts of the ground layer/ forest floor.

Answer 20

Its height is 0m. It is very dark and damp in here as as little as 1% of sunlight reaches this layer. Very little vegetation (only 6-7%) is found here as very few plants can survive on the forest floor. Many creepy crawlers can be found in this layer.

Question 21

What is litter? Where can it be found? Describe and explain the speed of the cycle in which plants absorb nutrients, die, and give back nutrients as dead leaves.

Answer 21

Rotting leaves and dead animals accumulate to form a layer of dead organic matter called litter, which decomposes to form hummus.
It can be found on the forest floor/ ground layer of a rainforest.
This process is rapid due to how dead leaves decay very quickly in the hot and wet climate of the rainforest.

Question 22

Why is litter important in a rainforest?

Answer 22

Rainforest soil is poor and infertile in general as all of their nutrients are washed away throughout the millions of years of weathering. Therefore, litter is an important source of nutrients for plants in the rainforest in order for them to be able to grow and survive.

Question 23

Name two examples of the plants that can be found in the forest floor/ ground layer.

Answer 23

Mosses and fungi.

Question 24

Why are there special adaptations in the leaves of rainforests?

Answer 24

This is because little sunlight penetrates the canopy layer in the rainforest due to the dense growth of plants; thus, the leaves of plants need to adapt to the lack of sunlight in addition to the heavy rainfall found in the rainforest.

Question 25

Name four characteristics of leaves that can be found in the emergent and canopy layers of TRF plants and describe their functions.

Answer 25

—Broad leaves + leaves that are arranged to face different angles
—Drip tip
—Very green leaves
—Waxy coating

Question 26

What are the functions of broad leaves that can turn to face different angles found in TRF plants in the emergent and canopy layers?

Answer 26

These leaves maximise the absorption of sunlight as there is much competition for sunlight in the emergent and canopy layers.

Question 27

What are the functions of the drip tips in leaves that can be found in TRF plants in the emergent and canopy layers?

Answer 27

Drip tips make it easier for water to run off leaves, so the water will be able to reach the ground surface and provide moisture and nutrients for plants in the TRF as there is keen competition for resources in the rainforest.

Question 28

What are the functions of the very green leaves that can be found in TRF plants in the emergent and canopy layers?

Answer 28

Very green leaves lead to a higher rate of photosynthesis so that plants can produce sufficient food for themselves as there is limited sunlight in the canopy and emergent layers.

Question 29

What are the functions of the shallow but extensive roots that can be found in TRF plants in the emergent and canopy layers?

Answer 29

The roots are shallow so that they can absorb water and nutrients on or near the surface of the forest floor. This is because most rainforest soil is very poor with all the nutrients available largely remaining at surface level as the soil layer in rainforests is thin due to the constant, heavy rain that washes them away.
The roots are extensive to increase the area over which water and nutrients can be absorbed from the soil, as there is strong competition for nutrients and water in TRFs.

Question 30

Describe buttress roots, and their functions in plants that can be found in the canopy and emergent layers of TRFs.

Answer 30

Buttress roots are large, wide roots with ridges found on all sides of a shallowly rooted tree, that can be up to 10m in height.
As shallow roots aren’t strong enough to support heavy, tall trees, buttress roots grow out from the tree trunk to create a large surface area, which helps support large trees and prevents them from falling over.

Question 31

Describe aerial roots, and their functions in plants that can be found in the canopy and emergent layers of TRFs.

Answer 31

Aerial roots are roots that are above the ground. They grow from the plant stem or leaf tissues.
They can absorb the moisture and dissolved minerals in the air as there may not be sufficient water and nutrients in the soil alone due to the strong competition for resources in TRFs.

Question 32

Name three characteristics of roots that can be found in the emergent and canopy layers of TRF plants.

Answer 32

—Shallow but extensive roots
—Buttress roots
—Aerial roots

Question 33

Name and explain the two characteristics of trunks that can be found in the emergent and canopy layers of TRF plants and describe their functions.

Answer 33

—Straight
—So that they can put more energy in growing tall to gain as much exposure to sunlight as possible, saving the extra time and resources needed to grow branches
—Branchless
—So that they can put more energy in growing tall to gain as much exposure to sunlight as possible
—So that they’ll be able to receive more moisture as more water is able to reach the ground surface
—Moreover, there is no use for trees that are not exposed to sunlight to grow branches, as even if extra leaves grow on the branches, they won’t be able to carry out photosynthesis

Question 34

Why do plants in tropical rainforests have to develop special features?

Answer 34

This is due to the keen competition for sunlight, space and nutrients in TRFs.

Question 35

Name the four types of special plant species that can be found in TRFs.

Answer 35

Epiphytes, climbers/ climbing plants, stranglers and parasites/ parasitic plants

Question 36

Describe and explain the special features of epiphytes and climbers.

Answer 36

They grow harmlessly upon other plants.
They survive by growing on or climbing up tree trunks so that they are able to reach a great height and absorb more sunlight.

Question 37

How do epiphytes and climbers get access to sunlight, nutrients and water respectively?

Answer 37

Epiphytes attach to trunks and branches in the canopy layer to absorb more sunlight. They obtain nutrients and water from the air, rain, water or debris accumulating around them.
Climbers are rooted in the soil at ground level and climb along tree trunks or other objects for physical support. Climbers wind the way up the tree trunks or other objects to get access to well-lit areas, and obtain nutrients and water from their roots in the soil.

Question 38

Name one example of an epiphyte and a climber respectively.

Answer 38

Orchid, liana

Question 39

Describe the life cycle of strangler plants. Also name a strangler plant.

Answer 39

1. They start their lives as epiphytes, sprouting from a small, sticky seed.
2. Later, they descend along the trunk of the host tree, eventually reaching the ground and entering the soil
3. After that, they quickly surround the host trees, blocking sunlight and causing the death of the host tree
4. The host tree then decomposes and provides nutrients for the strangler
5. At last, they become large hollows that provide shelter and breeding sites for bats, birds and other animals
   Fig tree.

Question 40

How do parasitic plants obtain nutrients?

Answer 40

They grow on other host plants and do not require chlorophyll or photosynthesis. They obtain most of the nutrients they need from the host by piercing through its leaves, stem, or trunk, and sucking the nutrients out of the host.

Question 41

Name and describe an example of a parasitic plant.

Answer 41

Corpse flower, aka stinky flower, as it emits a strong odour similar to rotting meat.
It can grow to be 3 feet across and weigh up to 15 pounds.
They have no visible leaves, roots, or stem. It attaches itself to a host plant to obtain water and nutrients.

Question 42

What is a plant that is adapted for capturing and digesting insects in the TRF called?

Answer 42

Carnivorous/ insectivorous plants.

Question 43

Why are tropical rainforests so important to us? Name three reasons.

Answer 43

—World’s largest pharmacy
—Lungs of the Earth
—Regulate water resources

Question 44

Explain how tropical rainforests are the world’s largest pharmacies.

Answer 44

The biodiversity of plants in TRFs is rich. Rainforest plants account for the raw materials needed to make 1/4 of western medicines, which is over 120 different drugs.
Moreover, around 70% of the plants the US National Cancer Institute considers to have potential anti-cancer powers are species found exclusively in the Amazon Rainforest.

Question 45

Describe the biodiversity of plants in TRFs.

Answer 45

In the TRFs of Southeast Asia, there are more than 250,000 plant species in one area.
In the TRFs of the Congo Basin, there are up to 100,000 plant species in the rainforest in West Africa.
In the TRFs of Amazon Basin, there are about 6,000 flora species in the rainforest of French Guiana.

Question 46

Explain how tropical rainforests are the lungs of the Earth.

Answer 46

Tropical rainforests grow luxuriantly. The plants in TRFs carry out photosynthesis, and stabilise the Earth’s climate through absorbing carbon dioxide, a greenhouse gas, and releasing oxygen, which we depend on for our survival. Rainforests are also referred to as “carbon sinks”.

Question 47

Explain how tropical rainforests help regulate water resources of the Earth.

Answer 47

Rainforests store water like a huge sponge. The Amazon forests alone store over half of the Earth’s rainwater.
Rainforests continually recycle huge quantities of water, feeding the rivers and lakes.
Without rainforests, droughts would become more common, leading to widespread famine and disease.

Question 48

Describe and explain the environment of deserts.

Answer 48

The air in deserts is often quite dry because the humidity of the air is usually very low. Low annual rainfall in deserts means there is insufficient rainfall for continuous vegetation growth. The dryness in deserts results in a discontinuous vegetation cover.

Question 49

Describe the characteristics of plants in deserts.

Answer 49

—Desert landscapes are often bare lands with only isolated patches of vegetation (so there is less competition for water); vegetation is sparse/ absent
—Very few trees can grow because they need more water
—Little biodiversity as many plants cannot survive in the hot and dry climate; plants that are found here are mostly small in size and short in height.
—The structure of vegetation in tropical deserts are simple, only consisting of 1 or 2 layers
—Plants found in desert, such as short, rough grasses and low bushes and cacti, have a high tolerance to drought

Question 50

What are the three types of plants that can be found in the desert?

Answer 50

Water conservers, drought resistant plants, drought avoiders.

Question 51

Name a water conserver, and six characteristics of that plant.

Answer 51

Cacti; fleshy, hollow expandable stem, green stem, waxy cuticles, spiky leaves, low in height and round-shaped, rain roots.

Question 52

Explain why cacti have fleshy, hollow/ spongy, expandable stems.

Answer 52

When there is no rainfall, cacti reduce water loss through transpiration by shrinking in size so that less of their surface area is exposed to sunlight.
When there is rainfall, they expand their fleshy, hollow stems so as to store water.

Question 53

Explain why cacti have green stems.

Answer 53

The green colour of their stems allow them to carry out photosynthesis as they have no green leaves.

Question 54

Explain why cacti have waxy cuticles.

Answer 54

It’s waxy bark allows it to reflect strong sunlight.

Question 55

Explain why cacti have spiky leaves.

Answer 55

These features help reduce the water loss of cacti through transpiration by lessening the surface area of their leaves, and prevents animal from eating them for the water that they contain.

Question 56

Explain why cacti are low in height and round-shaped.

Answer 56

These features help cacti avoid damages, for example, being uprooted by strong desert winds, as the desert winds are not as strong at ground level due to the friction between it and the ground, and the surface area of the cacti that is affected by the desert winds is reduced due to their round shape.

Question 57

Explain what are rain roots, and why cacti have them.

Answer 57

Rain roots refer to shallow but extensive roots. These roots spreads 10-15 feet away from the plant.
In brief showers which only wet a few inches of soil, the shallow roots of cacti help the plant maximise water intake from a large area.

Question 58

Name and describe the characteristics of an example of a cactus.

Answer 58

Saguaro. It is the largest cactus in the world, with a height of up to 10m.
—They have tiny hair like roots extending out of larger roots to absorb more rainfall.
—They carry out photosynthesis at night to reduce water loss as it is hotter at day.
—They are dark green coloured to carry out photosynthesis more efficiently.

Question 59

What are drought resistant plants? What is another name for these plants?

Answer 59

They are plants that can make use of the limited water in deserts and reduce water loss, able to survive arid or drought conditions; Drought tolerant plants.

Question 60

Describe the characteristics of drought resistant plants. Name one example of this type of plant.

Answer 60

They develop features to reduce water loss through transpiration, such as:
—thick bark
—small leaves
—double root system
The acacia tree.

Question 61

Describe a double root system.

Answer 61

In a double root system, there are shallow roots to collect surface water during light rain, and long deep roots called tap roots to tap ground water and anchor the plant in the soil. Tap roots are longer than the plant itself by up to 2-3 times.

Question 62

What are drought avoiders?

Answer 62

They are plants that avoid growing in dry seasons.

Question 63

What are the characteristics of drought avoiders? What is another name for drought avoiders?

Answer 63

They have short life cycles that can be completed within a few weeks.
They have dormant seeds; newly reproduced seeds can stay dormant in dry soil for a long period of time and wait for the next rain to come, only germinating when there is moisture/ rain.
Drought evaders.

Question 64

Name and briefly describe two additional types of desert plants.

Answer 64

Window plants hide underground and their transparent tops help absorb sunlight.
The white powder on quiver trees help reflect sunlight; moreover, they cut off their own branches and twigs during dry seasons.

Question 65

Describe and explain why there are oases in the desert.

Answer 65

An oasis is where the water table meets the surface of a desert. There are permeable rocks below the surface of a desert. Water is stored in the pores and opening in these rocks. The water table refers to the water level within these rocks. Therefore, when the water level of these rocks meet the surface of a desert, water flows out of the rocks and onto the surface.

Question 66

Why can human settlement and cultivated land in desert environments be found in or near an oases?

Answer 66

There is a continuous supply of water for vegetation growth and sustaining human life in oases. Therefore, cultivated land can be found here. Moreover, the dense vegetation that can be found here provides habitats and food for animals and humans. Therefore, human settlement can be found here.

Question 67

Name and briefly describe an example of an oases.

Answer 67

Siwa Oasis. It is a very isolated settlement, and is found in a deep depression that reaches below about 19m of sea level. Human settlement and cultivated land can be found here.

Question 68

Which layer of the TRF is the coolest one? Explain.

Answer 68

The shrub layer. The emergent and canopy layers are directly exposed to sunlight, and the young tree layer is also relatively hot due to the heat trapped underneath the canopy layer. The ground layer is also hot because the rainforest ground rapidly absorbs heat from the sun. Therefore, the shrub layer is the coolest layer out of the other layers.

Question 69

What do we call the layers beneath the canopy layer?

Answer 69

The understory layer.

Question 70

How do plants absorb nutrients?

Answer 70

They absorb nutrients through the absorption of moisture containing minerals and other nutrients.

Question 71

What are the functions of the waxy coatings on leaves that can be found in TRF plants in the emergent and canopy layers?

Answer 71

They waterproof the leaves of plants in TRFs, at the same time allowing the leaves to reflect the high intensity of sunlight found in rainforests so they lose less water through transpiration.