Australian Environment and Plant Evolution
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Australian Environment and Plant Evolution

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Questions and Answers

What environmental factor allows rainforest to grow in low nutrient soil?

  • High sediment levels
  • Low temperatures
  • High rainfall (correct)
  • Frequent sunlight

    • Which type of leaves become more prevalent as mean annual temperature increases?

  • Leaves with entire (smooth) margins (correct)
  • Rough-edged leaves
  • Leaves with wavy edges
  • Leaves with deeply lobed margins

    • What characteristic of toothed leaf margins assists gas exchange at low temperatures?

  • Reduced transpiration
  • Increased surface area
  • Enhanced light absorption
  • Slowed airflow (correct)

    • In which environment would rainforest primarily thrive according to nutrient availability?

    <p>Low nutrient soil with high rainfall</p> Signup and view all the answers

    What color line represents high light plants in the described leaf physiognomy?

    <p>Light green line</p> Signup and view all the answers

    What advantage does the elaboration of the zygote into a sporophyte provide?

    <p>Higher production of spores</p> Signup and view all the answers

    Which of the following is NOT a problem faced by aquatic organisms adapting to land?

    <p>Heat insulation</p> Signup and view all the answers

    Which tactic is commonly used by organisms to minimize exposure to heat and drought?

    <p>Dormancy for a substantial part of the life cycle</p> Signup and view all the answers

    What helps reduce heat load in some desert plants like the Joshua tree?

    <p>Vertical shoot-body architecture</p> Signup and view all the answers

    What do the nocturnal or crepuscular foraging strategies help organisms avoid?

    <p>Heat stress during daylight</p> Signup and view all the answers

    How does the gene expression in sporophytes benefit land plants?

    <p>Preventing expression of deleterious alleles</p> Signup and view all the answers

    What is one major challenge of terrestrial life that is particularly significant for aquatic organisms?

    <p>Availability of water</p> Signup and view all the answers

    Which adaptation is specifically mentioned as a mechanism for surviving extended droughts?

    <p>Hibernation and dormancy</p> Signup and view all the answers

    What adaptation helps desert plants like Brigalow reduce water loss?

    <p>Sunken stomata to minimize gas exchange</p> Signup and view all the answers

    How do smaller leaves contribute to the cooling of desert plants?

    <p>By cooling faster due to thinner boundary layers</p> Signup and view all the answers

    What is the primary role of RuBisCO in C3 carbon fixation?

    <p>Binding CO2 and H2O to produce 3PGA</p> Signup and view all the answers

    What happens when RuBisCO binds with O2 instead of CO2?

    <p>It creates a problem molecule called Phosphoglycolate</p> Signup and view all the answers

    Which structural adaptation helps desert plants cool more effectively during specific times of the day?

    <p>Vertical leaves for maximum early morning and evening irradiation</p> Signup and view all the answers

    What physiological response occurs in an organism to minimize heat loss in cold environments?

    <p>Vasoconstriction to reduce blood flow to the surface</p> Signup and view all the answers

    Evapotranspiration in desert plants primarily helps with what aspect of plant physiology?

    <p>Regulating internal temperature during water availability</p> Signup and view all the answers

    Which feature of leaves can affect their irradiation and cooling rate during the day?

    <p>Angle of orientation and size</p> Signup and view all the answers

    What factors contribute to flowers being more stable over evolutionary time than leaves or bark?

    <p>Constraints of animal intermediaries in reproduction</p> Signup and view all the answers

    Which characteristic differentiates Australia from other continents in terms of its flora and fauna?

    <p>It has the least predictable rainfall</p> Signup and view all the answers

    What is a result of the nutrient poor soils in Australia?

    <p>Open sclerophyllous/xeromorphic vegetation</p> Signup and view all the answers

    What role does fire dependence play in Australian ecosystems?

    <p>It encourages open communities</p> Signup and view all the answers

    Which of the following accurately describes the impact of plate tectonics on Australia?

    <p>It contributed to interactions with Asia</p> Signup and view all the answers

    What characteristic is associated with the Australian climate?

    <p>Frequent wildfires and arid conditions</p> Signup and view all the answers

    How do resource deficits impact the food chain in ecosystems?

    <p>They amplify through the food chain, impacting the top predators</p> Signup and view all the answers

    What is a result of Australia’s diverse ecosystems in terms of animal life?

    <p>Vast reptile diversity</p> Signup and view all the answers

    What are scleromorphic leaves typically associated with?

    <p>Xerophytic adaptations to dry conditions</p> Signup and view all the answers

    What influences the diversification of fauna in Australian ecosystems?

    <p>Open woodland and grassland habitats</p> Signup and view all the answers

    Which tree species is a common example found in Warm Temperate Rainforest?

    <p>Ceratopetalum</p> Signup and view all the answers

    What is the main characteristic of Cool Temperate Rainforest?

    <p>It includes tree species such as Nothofagus and Phyllocladus.</p> Signup and view all the answers

    Which type of rainforest includes a mix of old endemic and Asian migrant species?

    <p>Wet tropical/sub-tropical rainforest</p> Signup and view all the answers

    What factor might influence the boundaries between sclerophyll and non-sclerophyll vegetation?

    <p>Availability of moisture</p> Signup and view all the answers

    Which tree species is NOT mentioned in the context of Dry Rainforest?

    <p>Ceratopetalum</p> Signup and view all the answers

    Why can't Eucalyptus regenerate in low light conditions?

    <p>It requires fire for regeneration.</p> Signup and view all the answers

    In what type of rainforest would you likely find stinging trees?

    <p>Dry Rainforest</p> Signup and view all the answers

    What determines when the last major fire occurred in certain ecosystems?

    <p>Historical patterns of vegetation changes</p> Signup and view all the answers

    Study Notes

    Flowers and Evolution

    • Flowers are more stable over time than leaves or bark due to environmental selection pressures, interaction constraints of sex, and animal intermediaries.

    Australian Environment

    • Australia is the flattest inhabited continent with low levels of erosion, nutrient poor soils, and unpredictable rainfall.
    • Australia is prone to fires.
    • These factors have led to open sclerophyllous/xeromorphic vegetation, a diverse reptile population, ant/termite dominated ecosystems, plant symbiosis, and open woodland and grassland animals.

    Leaf Types

    • Xeromorphic leaves are adapted to dry environments.
    • Scleromorphic leaves are hard and leathery, common in blue gums.
    • Deciduous leaves are shed during dry periods, common in white ash.

    Australian Plate Tectonics

    • The Australian Plate is moving north and colliding with Asia, leading to a biotic interchange.

    Fire Dependence

    • Fire dependence encourages open communities.
    • Serotiny is a seed dispersal strategy where seeds are released after a fire.
    • Epicormic growth is when new shoots emerge from dormant buds on the stem.

    Australian Megafauna

    • Australia was once home to giant reptiles such as Megalania and Genyornis.

    Plant Reproduction: Sporophyte vs. Gametophyte

    • Sporophyte plants produce spores.
    • Gametophyte plants produce gametes (sperm and egg).
    • The elaboration of a zygote into a sporophyte has several advantages:
      • Increased spore production.
      • Prevention of recessive deleterious alleles.
      • Generation of variability in the sporophyte generation.

    Land Plant Challenges

    • Land plants face several challenges:
      • Gas exchange.
      • Lack of buoyancy.
      • Locomotion.
      • Obtaining food.
      • Desiccation.
      • Specific heat and thermal conductivity.

    Plant Phylogeny and Fossils

    • Plant phylogeny refers to the evolutionary history of plants.
    • Transitional fossils provide evidence of evolutionary change.

    Evasion Tactics for Heat and Drought

    • Dormancy is a strategy used by many organisms to survive harsh conditions.
    • Nocturnal or crepuscular foraging helps to reduce heat exposure.

    Reducing Heat Load

    • A low surface area to volume ratio helps minimize heat load.
    • Reflective bark and leaves reduce solar radiation absorption.
    • Vertical shoot architecture increases airflow and reduces heat absorption.

    Leaf Size and Heat Load

    • Smaller leaves cool faster than larger leaves.
    • Vertical leaves help minimize heat load by absorbing more radiation in the early morning and evening.

    Minimizing Water Loss

    • Desert plants minimize water loss through microphylly (small leaves), deciduousness, sunken stomata, waxy leaves, and thick cuticles.

    Controlling Heat Loss

    • Vasodilatation opens blood vessels to increase heat loss.
    • Vasoconstriction closes blood vessels to reduce heat loss.

    C3 Carbon Fixation

    • C3 carbon fixation is a process where RuBisCO binds with carbon dioxide to form 3-PGA.
    • Oxygen competes with carbon dioxide for binding sites, leading to the production of phosphoglycolate, which requires energy to breakdown.

    Australian Rainforest Types

    • Warm Temperate Rainforest: Dominated by Ceratopetalum, often found in areas with poor soil, restricted to areas of poor soils.
    • Cool Temperate Rainforest: Dominated by Nothofagus (beech) and Phyllocladus (celery pine).
    • Dry Rainforest: Dominated by Araucaria and Dendrocnide (stinging tree).
    • Wet Tropical/Sub-tropical Rainforest: A mix of old endemic and Asian migrant species.

    Rainforest Boundaries

    • Rainfall, soil conditions, and fire history all impact the boundaries between sclerophyll and rainforest vegetation.
    • Rainforest vegetation can only grow in areas with high rainfall when the soil is low in nutrients.
    • Rainforest vegetation can grow in areas with lower rainfall when the soil is high in nutrients.

    Leaf Physiognomy and Climate

    • Leaf shape and texture are influenced by climate.
    • Rainforest leaves tend to be elliptical with smooth margins.
    • The proportion of species with toothed margins decreases as temperature increases.
    • Toothed margins help to slow airflow for better gas exchange at lower temperatures.

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    Description

    Explore the unique adaptations of plants in the Australian environment, including xeromorphic and scleromorphic leaves. Delve into how geological factors and fire dependence shape ecosystems and plant evolution in Australia. This quiz covers critical concepts like plate tectonics and ecological diversity.

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