Lecture 3 - RH Flashcards Preview

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Flashcards in Lecture 3 - RH Deck (25)
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1
Q

What is the gross level and nett level of photosynthesis?

A

Gross level is the maximum capacity of photosynthesis for a particular species of plant.

Nett is the gross photosynthesis minus consumption of biomass during respiration.

2
Q

What are the environmental factors that affect ecosystems?

A

Light

Temperature

Water

Wind

Nutrients

Slope and aspect

3
Q

What is a sun plant and a shade plant?

A

Shade plants have low light compensation points and so can produce carbs from little light. (usually found in the understorey)

Sun plants need lots of sunlight and have high nett photosynthetic rates.

4
Q

What are leaves like in sun and shade plants?

A

Sun plants have thick and hard leaves.

Shade plants have thin and soft leaves

5
Q

What causes leaf cells to be hard in sun plants?

A

sclerenchyma cells

6
Q

How can temperature influence an ecosystem?

A

Limiting temperatures can influence life cycle

Optimum temperature for some plants allow them to produce their greatest biomass

7
Q

Is the temperature of the environment a good indication of optimum temperature?

A

Where an organism grows is not necessarily a good indication of its optimum temperature

8
Q

What is the difference between a photosynthesis vs leaf temperature curve that describes a plant adapted to hot environment (C4 plants) and a plant adapted to cold environments (C3 plants)?

A

A cool adapted plant has a large optimum range of temperatures which drops off at a certain high temperature.

A hot adapted plant has a small range of optimal temperatures and photosynthesis increases constantly until the temperature is too high

9
Q

What is the difference between C3 and C4 plants?

A

Carbon dioxide is stored in C4 plants but not in C3 plants.

C4 plants photosynthesize at night rather than during the day to avoid losing water.

10
Q

What are the important aspects of water taken into account when thinking about ecosystems?

A

Rainfall + evapotranspiration

Salinity

Each species has a minimum water demand

Balance between availability in the soil

11
Q

How do plant species minimise output?

A

Waxy cuticle and hairy surfaces

12
Q

What happens to species living in areas with lots of available water?

A

More species can cope but there is more competition as well

13
Q

Name forests from most water to least water:

A

Rainforest -> Closed forest -> Open forest -> Mallee

14
Q

Name shrubland from most water to least:

A

Tall -> Low

15
Q

What are the Australian multi-stemmed eucalypts?

A

Mallee

Snow Gum

16
Q

Why is salinity such an issue with water uptake by plants?

A

It affects the bioavailability of water through a decrease in the osmotic pressure into the roots thus slowing rate of water uptake.

17
Q

What kind of species dominate salty habitats?

A

Salt-tolerant species dominate salty habitats

18
Q

What are the effects of wind on plants?

A

Affects rate of transpiration

Causes disease

Causes sand to move onto leaves

Windy habitats are also stressful habitats

19
Q

is sand high in nutrients?

A

No

20
Q

How is the ability of soil to store nutrients measured?

A

Cation Exchange capacity (CEC)

21
Q

How does soil type affect vegetation?

A

Plants are adapted to a certain amount of nutrients so there are abrupt changes in vegetation with changes in soil type

22
Q

What is a mesophytic habitat?

A

A non-extreme environment with relatively good levels of water etc

23
Q

What is the biodiversity like in mesophytic habitats?

A

Very low due to competition resulting in one dominant species

24
Q

How does slope and aspect affect ecosystems?

A

Interacts with water via drainage. Less water in the higher areas compared to lower areas

Any slope facing north gets more sun then slops facing west

More wind on top of the slope then on the bottom

25
Q

What are some biotic factors that are relevant to ecosystems?

A

Competition between like species

Predation: lots of prey = lots of predators