Question

1. What are the four key environmental limitations to plant growth, considered at global-
scale?
2. What are the major environmental factors that influence decomposition rates in
ecosystems?
3. Stomata are first seen in plant fossils from about 420 million year ago (Mya). List one
advantage and one disadvantage of stomata.
4. Cuticles are first seen in plant fossils from about 450 million year ago (Mya). List one
advantage and one disadvantage of cuticles.
5. An important evolutionary advance seen in angiosperms is that vascular tissue is largely
made up of vessels rather than tracheids. Describe one key advantage and one key
disadvantage of vessels over tracheids.
6. Give two reasons why bryophytes are generally constrained to wet habitats.
7. The most central and abundant enzyme in photosynthesis is
dominant pigment is_______.
while the
8. At what time of day does dark respiration happen?
9. C4 photosynthesis relies on several enzymes, most especially the initial fixation step
which is catalysed by the enzyme called______________ .
10. Name 4 of the largest (most speciose) plant families in Australia.
11. Name one characteristic plant genus in each of these Australian vegetation types:
a. Chenopod shrubland
b. Mallee woodland
c. Mulga woodland
d. Savanna
12. What functional roles do root hairs and mycorrhizas have in common?

Answer 1

1) Four key environmental limitations to plant growth considerd at global scale are SUNLIGHT,TEMPERATURE,WATER,AIR.

SUNLIGHT: sunlight is important for photosynthesis through which the plants get energy.

TEMPERATURE: temperature affects the plant growth. some plants grow in low temperature and some in high temperature. change in temperature limits plant growth.

WATER: water is an essential component of physiological processes in plants.

AIR:oxygen and carbondioxide in the air are important for physiology of the plants.oxygen is essential in respiration for the production of energy.

nutrient such as nitrogen,phosphorus,potassium also play important role inplant growth.

2) a] BIOLOGICAL ACTIVITY:bacteria,fungi and other microbes feeding on the organic material are important for decomposition rates.

b]MOISURE LEVEL: low level of moisure causes deprivation of oxygen to the microbes and slows the decomposition rates and high moisure or water decomposes faster

c]OXYGEN LEVEL: high oxygen level causes more biological activity and decomposes the organic matter faster. low oxygen level slows the decomposition rate.

d]SOIL ph; a ph less than 7 indicates acidic and it slows down the decomposition and ph more than 7 indicates alkaline and its faster the decomposition .

e] TEMPERATURE: at temperature of 40 degree faranheit or above the bacteria activity is more and decomposition rate is more. it is low in cold environment.

3)ADVANTAGE: A] it provides coolness to the plant.

B]osmotic balance is maintained by process of transpiration

DISADVANTAGE:A] when the weather is hot, more water is lost

B]excess transpiration reduses growth of plants

4)ADVANTAGE;A] cuticles protect photosynthetic cells.

B] insulates against heat.

5) ADVANTAGE; A] all the vessels are connected to each other at ends through perforated tube like structures which gives strength to the plant body.

DISADVANTAGE; A] vessel elements have low surface volume ratio compared to tracheids

B] vessel elements are shorter than the tracheids.

6) A] brophytes have no vascular tissue so they not able to take water from the soil and transport to other higher tissues.

B] brophytes also need wet environment for reproduction because it lacks pollen tubes to facilitate fertilization.

7) RIBULOSE 1,5-BIPHOSPHATE carboxylase\oxyhase (rubisco)

8) dark respiration also known as calvin cycle . they do not reqire sunlight to complete photosynthesis. it mostly occur in between 6PM TO 6AM.

9) PHOSPHOENOLPRUVATE (PEP) CARBOXYLASE

10) A] MYRTACEAE

B]POACEAE

C]FABACEAE

D]ASTERACEAE

12) root hairs collect water and minerals in the soil.mycorrhizal fungi come into contact with root hairs adding ability to gather more nutrients and water from the soil through the fungus.