prof sample questions - midterm

Question 1

Explain four features that can be used to distinguish members of the Domain Bacteria from the Domain Archaea

Answer 1

a) rRNA sequence
b) Archaeal membrane lipid tails are branched and sometimes linked.
c) Some bacteria can photosynthesize
d) Bacterial cell walls contain some peptidoglycan, Archaea do not.
e) Some Archaea can synthesize methane.
f) Some Archaea can live in extremely hot or saline environments.

Question 2

Describe two distinct features of viruses that allow them to evolve extremely rapidly

Answer 2

*Extremely rapid reproduction in host cell
*Extremely large number of progeny per reproductive event
*Nucleic acid reassortment can occur when two strains infect the same cell (antigenic shift)

Question 3

Viruses have been detrimental to human societies in many different ways. Support this
statement using three separate examples

Answer 3

i) Viruses cause many serious human diseases (e.g. COVID 19).
ii) In the history of human colonisation, virus transmission to societies that had not
developed immunity resulted in major local population declines (e.g. Incans,
Mexicans, North American Indigenous peoples)
iii) Viruses could be used a bioterrorism weapon (e.g. anthrax)
iv) Viruses have been implicated in many serious animal and plant diseases that
have affected human food supply

Question 4

“We now live, as Earth always has, in an Age of Bacteria. These simplest organisms will
dominate our planet (if conditions remain hospitable for life at all) until the sun
explodes.” Stephen J Gould, 1998. This famous biologist considered Prokaryotes as
relatively ‘simple’ organisms compared to Eukaryotes. Make two points in favour of, and two points against this conclusion

Answer 4

Points in favour:

*No nucleus
*No/little membrane compartmentation
*Unicellular (only)
*No cytoskeleton
*No sexual reproduction
*Simple flagella compared to Eukaryotes

Points against:
*Highly diverse metabolic capacities/ecologies
*Extraordinary fundamental (DNA sequence for rRNA) genetic diversity
*Very rapid growth under favourable conditions
*Capacity for very long, highly protected, dormancy

Question 5

Prokaryotes (and some Eukaryotes) are microscopically small. Outline two positive and two negative implications of being microscopically small

Answer 5

Positives
*Rapid reproduction
*Extensive easy dispersal

Negatives
*Nearby water availability is critical for metabolism
*Large surface area to volume means water medium is very viscous – greatly restricting motility
*Small size means they are readily predated on by larger organisms

Question 6

Prokaryotes were not only essential to the ancestral origins of the Tree of Life, but also to much of its subsequent development and diversification. Make two points to support the latter notion that prokaryotes have enhanced diversity among the eukaryotes

Answer 6

Endosymbiosis of two prokaryotes gave rise to the first eukaryotes (aerobically respiring,
nucleus-containing organisms), which ultimately diversified into many lineages of heterotrophic eukaryotes

Endosymbiosis of a heterotrophic eukaryote with a cyanobacteria (Prokaryote) gave rise to the first photosynthetic eukaryotes, which ultimately diversified into all the members of the higher
plants (Archaeplastida)

The diverse and unique metabolic capabilities of prokaryotes is critical to the biogeochemical
cycling of many growth-limiting nutrients (N, P, Ca, etc) and therefore to the ongoing
availability of these nutrients to Eukaryotes, thereby providing the resources necessary for their growth and diversification

Prokaryotes such as cyanobacteria were responsible for greatly increasing the concentrations of oxygen in the atmosphere.. thereby providing a critical resource that supports aerobic
respiration in the Eukaryotes

Question 7

Provide two reasons to explain why prokaryotes are generally only metabolically active when their cells are in contact with external water

Answer 7

Prokaryotic cells are reliant on an external water film around them so that:
a. diffusion can supply nutrients and organic matter
b. diffusion will remove waste excretions
c. water is necessary as a metabolite

Question 8

Explain what is meant by the term chemoautotroph to describe an organism’s metabolism in terms of its acquisition of energy and carbon, and briefly describe an example of a globally significant biogeochemical reaction that is mediated by a chemoautotroph

Answer 8

A chemoautotroph obtains its energy by chemical oxidation of a reduced compound
such as Fe2+, NH4+, S, CH4, and its carbon by reducing CO2 (or HCO3) gas to an
organic compound such as carbohydrates.
Chemoautotrophs have globally significant and critically important impacts on the
biogeochemical cycling of:

i) iron oxidation (iron-oxidizing bacteria are responsible for some rusting and
rock weathering)

ii) nitrification (nitrifying bacteria convert ammonium in agricultural fertilizer
to nitrate that is particularly prone to leaching into aquatic ecosystems
causing eutrophication)

iii) methanogenesis (some methanogens convert hydrogen to methane -which is a
particularly powerful greenhouse gas)

Question 9

Describe two lines of evidence supporting the hypothesis that life evolved in deep sea
thermal vents

Answer 9

i) Thermophiles are particularly frequent at the base of the Tree of Life

ii) The reducing conditions in vents are consistent with the biochemical traits of
early life forms (heterotrophic, and anaerobic)

iii) Most of the fundamental housekeeping (cellular maintenance) proteins and
biochemical processes seem to have a heritage reflecting a hydrothermal
environment

iv) UV levels are low in vents relative to the ocean surface meaning nucleic acid
degradation was minimal

v) Strong pH gradient in alkaline-type marine hydrothermal vents may have
favoured the evolution of the ion pumping and membrane system which are
necessities for biochemical energy use. ( Some students may have read the
recommended but not required book by Nick Lane entitled The Vital Question in
which he argues that life probably originated in alkaline-type marine
hydrothermal vents because the strong pH gradient may have favoured the
evolution of the ion pumping and membrane system which are necessities for
biochemical energy use.)

Question 10

Make four points in favour of the view that viruses are not living organisms

Answer 10

i) Require host cell to replicate.
ii) Do not grow either by size increase or by dividing.
iii) Cannot respond to external stimuli.
iv) Lack cellular structures.
v) Lack capacity to metabolize independently

Question 11

Elucidating the fundamental biology of viruses has been beneficial to human societies in many different ways. Give an example to demonstrate this point (1 mark), and clearly explain the societal benefit

Answer 11

i) Understanding smallpox and its relation to cowpox led to the development of
vaccines as an immunization preventative medical procedure.

ii) Understanding that many viruses function as bacteriophages has resulted in the
development of very important tools in molecular biology to conduct gene transfers
and cloning.

iii) Understanding the role of the external viral spike proteins that serve as antigens
during human infection has provided the basis for developing mRNA vaccines such
as for COVID-19

Question 12

The life cycles of all sexually reproducing organisms can be classified into three principal types. Name the generalized life cycle of the type which applies to the Red algae

Answer 12

Alternation of generations

Question 13

Suggest a reason why these triphasic red algal species may have evolved this capacity for two separate diploid stages

Answer 13

Members of the Red Algae group do not have a flagellum in the gamete/spore
stage, although it seems that their common ancestor with other algal groups did.
Perhaps the flagellum is ineffective for gamete motility in the turbulent coastal
surface water environments in which these organisms grow, and therefore it has
been lost over evolutionary time. The production of multiple successive diploid
forms may be a means to maximize the numbers of sporophytes that will each
contain some cells that undergo meiosisis thereby increasing the numbers of
individual male and female gametophytes and thus gamete production and the
likelihood of compatible mating and successful fertilization.**

Question 14

Explain two lines of evidence indicating that some Euglenoids gained the capacity to
photosynthesize by secondary endosymbiosis?

Answer 14

Evidence includes the facts that photosynthetic Euglenoids have
chloroplasts that:

a. contain Chlorophyll b

b. are contained by a triple layer of plasma membranes

c. some presumably less advanced (more ancestral) Euglenoids are heterotrophs

Question 15

Fungi are more important than bacteria and archaea as decomposers of dead plant and
animal organic matter in terrestrial ecosystems. Make three points to support this statement

Answer 15

 Fungi can have a hyphal growth form that allows them to grow toward and
within their substrate

 Fungi are not as dependent as bacteria on the immediate proximity of water and
nutrients to support metabolism during decomposition because they can
translocate water and nutrients within their hyphae from moist or fertile sources elsewhere, and therefore can decay relatively dry, nutrient-poor substrates.

 As a eukaryote, fungi are capable of sexual reproduction meaning that in each successive generation, they can generate relatively high levels of genetic diversity
as compared to bacteria… and therefore they can evolve relatively quickly to
adapt to diverse decomposer niches on land.

 Fungi can synthesize specialised wood decay enzymes

 Fungi may be better adapted than bacteria to dispersal on land because they can produce large fruiting bodies to release spores into the air and so disperse to other organic matter substrates

 Plant colonisation of land occurred long after bacteria evolved, and at about the
same time as the earliest land fungi (~1 bya). Therefore, both fungi and bacteria have had the chance to evolve on organic substrates on land for about the same
time. As a result, the earlier origin of bacteria may not have been any particular
advantage.

Question 16

Compare and contrast fungal and vascular plant reproduction by describing three
distinctive features of the genetics and lifecycles of the Kingdom Fungi

Answer 16

i) Sexual reproduction is by zygotic meiosis in most fungi whereas vascular plants have an alternation of generations life cycle.

ii) Zygotic (diploid) stage in fungi is unicellular and often represents the
dormant highly protected stage of the life cycle that is favoured when
environmental conditions are not favourable for growth.

iii) Cytoplasmic (plasmogamy) and nuclear (karyogamy) fusion are substantially
separated in time in many fungi (e.g. Ascomycota and Basidiomycota),
meaning there is a distinct and prolonged dikaryotic phase.

iv) Asexual reproduction is extremely common in most fungi, but in a much
smaller proportion of vascular plants.

Question 17

‘Dry rot’ refers to decomposition of wood in a dry environment by certain fungi. Outline
two distinctive features of these fungi that allow them to achieve this process?

Answer 17

i) Fungi have the capacity to translocate water and nutrients along the mycelium from hyphae that are in contact with moist areas elsewhere to other hyphae that are
actively decomposing completely dry wood

ii) Certain dry rot fungi can synthesize substantial liquid water as a byproduct of
glycolysis

iii) Dry rot fungi can synthesize highly specialized wood-decaying enzymes

Question 18

Describe the structure of a crustose lichen in cross-section by explaining each of the four
layers in sequence from the top surface to the base

Answer 18

Sandwich structure with alga enclosed beneath a thin upper relatively dense layer of
fungal tissue, with a thicker more ‘spongey/open/porous fungal layer below the algal layer, and then a thin fungal layer at the base

Question 19

Explain the function of the fungal inner layer

Answer 19

The inner layer of low density fungal tissue provides excellent water uptake and storage.

Question 20

Indicate how lichens acquire their supplies of carbon and sulfur and which symbiont participant is involved in each case

Answer 20

Alga fixes CO2 during photosynthesis, some of which is used for its own metabolism and
some of which is translocated to the fungus.
Sulfur is generally acquired from atmospheric deposition of particles and in soluble form
in rainfall onto the uppermost surface fungal layer

Question 21

Diversity begets diversity. Explain this central concept of the course

Answer 21

The evolution of diverse traits among species enhances the potential for
subsequent evolution of further diversity in traits, and ultimately often leads to
increased numbers of species

Question 22

Trillium species, Daffodils and Lilies are all members of the Monocot plant group.
Describe two common structural features of the flowers in this group

Answer 22

Radial symmetry (generally)
Floral parts in threes
Embryo that produces single cotyledon

Question 23

Describe a distinctive characteristic feature of the emerging germinating embryo in monocot plant group

Answer 23

All monocots have a single cotyledon leaf.. and so on germination this single leaf
is the first structure to emerge. (Technical term for first monocot leaf is
coleoptile. By contrast, the the germinating embryo of the Eudicota all have two
emerging leaves (cotyledons).)

Question 24

Describe the typical mature leaf shape of the monocot plant group

Answer 24

Leaves are usually long and often narrow, terminating in a single-point (i.e.
without indentation (grass-like as compared with a Eudicot maple leaf for example). (Leaf veins are usually parallel)

Question 25

Nitrogen and Phosphorus are both essential elements for all living organisms. Indicate two important and functionally different biochemical molecules for each of these two elements

Answer 25

**Nitrogen – Amino acids (and therefore proteins)**, Nucleotide bases (e.g. ATCG) in **DNA/RNA**, Chlorophyll pigments, ammonium, nitrate...??? **Phosphorus – ATP energy, Phospholipids in membranes**, Nucleotide phospho- ribose backbone in DNA/RNA, phosphate sugars in metabolism, Bones in vertebrates - made of calcium phosphate, Phosphate for signalling...???

Question 26

Name two other essential nutrients that vascular plants generally obtain from soil

Answer 26

**Potassium** Calcium Magnesium Sulphur **Iron**

Question 27

Angiosperms contain enormous structural diversity. Give two distinct examples of conventional roots that have become modified by evolution into other structures

Answer 27

**Evolution within the angiosperms has resulted in modification of conventional roots into storage roots (e.g beetroot), prop roots (e.g. maize)**, green roots (e.g. epiphytes such as orchids), cluster roots (e.g. Proteaceae of phosphorus-impoverished soils)

Question 28

Some plants can have relatively low root:shoot biomass ratios. Explain the evolutionary selection pressure that would lead toward evolution of a low root:shoot biomass ratio, and describe the likely environmental properties of a habitat-type where such evolution would likely occur

Answer 28

Shoots are critical to providing photosynthetic capacity....while roots provide access to soil nutrients and water. A plant species is likely to evolve toward biomass allocation to organs that enhance uptake of the most growth-limiting resources. An environment that has low light, and perhaps moderate to high soil fertility is likely to result in the evolution of a low root:shoot biomass ratio because the belowground resources are likely to be less growth-limiting than light availability. Such environments include the understory of forests – especially tropical forests

Question 29

Angiosperms contain enormous structural diversity. Give two distinct examples of leaves that have become modified by evolution into other structures

Answer 29

Evolution within the angiosperms has resulted in modification of leaves into tendrils, **hairs**, reproductive leaflets, spines, and **storage leaves (such as in onion)**

Question 30

Explain the evolutionary selection pressure that would lead toward evolution of such a high proportion of root surface area

Answer 30

Surface area is a primary determinant of nutrient uptake... and a plant species is likely to evolve toward preferential allocation to new growth of surface area of tissue that would enhance uptake of the most growth-limiting resources

Question 31

Structure usually relates to function in living organisms. Illustrate this concept by providing and explaining three broad examples of structural advances in organisms discussed in class or in the text readings in the section of this course that were associated with new evolutionary functions

Answer 31

**i) Flagellum in bacteria permits locomotion ii) Multicellularity permits the capacity for specialization of tissues within an organism (e.g. plant roots and shoots) iii) Membrane-bound organelles permit cellular organization and localizes specific metabolic processes (e.g. yeast cell of Phylum fungi)** iv) Nuclear membrane permits separation of transduction from translation and thereby promoting more complex gene regulation v) Cytoskeleton permits controlled guidance and internal movement within cytoplasm vi) Diploid chromosomes permit the process of meiosis and consequently sexual reproduction, as well as heterozygous condition, and the presence and expression of multiple alleles for each gene within a populatio

Question 32

Briefly describe an ecological context that can promote the onset of sexual reproduction in these bread mould fungi

Answer 32

The fungus is likely to begin sexual reproduction producing the zygospore once either a) the food resource is depleted b) the environmental conditions become harsh **c) an appropriate sexually compatible mate is detected**

Question 33

The Kingdom Fungi contains many distinctive biological features compared to the other eukaryotic Kingdoms. List four clearly separate and distinct biological characteristics of the Fungi to support this statement

Answer 33

**Dikaryotic cells (containing two distinct haploid nuclei) are common** and are even the dominant life stage in the Basidiomycota. **Individual fungi can extend across a very wide range of spatial scales** (microns to kilometers) **Fungi represent a very large number of the total species on Earth** (Expected total number on Earth is second only to Insects ) **Dry rot fungi are capable of decomposing completely dry wood** (by translocating or synthesizing water to support their metabolism) Fungi have cell walls made of chitin Fungi produce hyphae/mycelium (at least many do)

Question 34

Illustrate this concept of "diversity begets diversity" using four clearly separate and distinct examples that you have learnt about in this course

Answer 34

**i) Diversity in bacterial metabolism permitted primary endosymbiosis because the process involved those particular bacteria that had evolved a capacity for aerobic respiration. This primary endosymbiosis ultimately gave rise to the first heterotrophic eukaryotes and so was a starting point for extraordinary subsequent diversification across the Eukarya.** **ii) Diversity in the evolution of the photosynthetic bacteria resulted in some that produced oxygen (cyanobacteria) ultimate resulted via primary endosymbiosis in the first photosynthetic eukaryotes which went on to diversify greatly.** **iii) Diversity in the evolution of the photosynthetic bacteria resulted in some that produced oxygen (cyanobacteria) ultimately paving the way for oxygen accumulation in the atmosphere and therefore selection for aerobic metabolism which spurred the evolution of diverse aerobic heterotrophs across the Eukarya.** iv) Diversity in unicellular members of the Archaeplastida was a necessary precursor to the secondary and tertiary endosymbiosis whereby some dinoflagellates and other heterotrophic protists acquired photosymbionts which subsequently led to substantial diversification within these algal groups. **v) Diversity in prokaryotic fission (i.e. mutation) probably led to the evolution of diploidy which paved the way for polyploidy which has been such an important mechanism for speciation in higher plants.** vi) Diversity in the evolution of diploidy also paved the way for sexual reproduction and the incipient processes of recombination and meiosis that generate further genetic diversity, and therefore usually enhanced phenotypic and species diversity across all Eukarya. vii) Diversity in plasmamembrane folding may have led to the evolution of the nuclear membrane within an ancestral eukaryotic cell and thus to enhanced levels of complexity and compartmentation, signaling and trafficking that ultimately contributed to the evolution of much more complex organisms (e.g. the possibility of post-transcriptional modification of mRNA in the cytosol contributes to enhanced genetic diversity). viii) Diversity in primitive roots (rhizoids) in certain green algae were a precursor to the evolution of much more advanced roots in the highly diverse vascular plants. ix) Diversity in initial fungal species on land was greatly enhanced by their coevolution with the substrates on which they feed (dead plant and animal tissues, fungal pathogen targets, mutualisms etc) all of which were evolving and diversifying, resulting in corresponding fungal diversification.

Question 35

Write out the ‘equation of life’ that includes both autotrophic and heterotrophic components and includes energy inputs and outputs

Answer 35

light --------------v (HCHO)n + O2 -> <- CO2 + H2O + energy

Question 36

Why are most photosynthetic organisms in aquatic systems generally small and structurally undifferentiated compared to their counterparts on land

Answer 36

The water medium in aquatic environments provides buoyancy to keep the photosynthesizing organism up close to the top surface where light availability is highest, and where there is ready diffusion of critical nutrients such as N, P, and dissolved CO2. Consequently, there is no selection pressure for complex structural tissues, and furthermore **unicellular organisms are ideal because they have a relatively large surface area to volume ratio for nutrient uptake and waste release.** By contrast, **on land, photosynthetic organisms are generally multicellular to produce multiple specialized structural tissues to acquire and compete for the resources they need.** For example, to access a water supply, most plants are rooted in the soil. The resulting immobility means they develop into populations of individuals that cannot escape from direct competition with each other for light, water, and nutrients. Hence **there is an evolutionary selection pressure to grow tall to reach the canopy and avoid shading of the light resource by other species**, meaning the development of considerable stem structural tissue in the shoot, which then must be supported by substantial anchoring root structural tissue belowground

Question 37

Electricity generation facilities in many parts of the world today are dependent on diverse ancestral members of the Fern group (Pteridophytes). Explain this statement

Answer 37

The Pteridophytes include lycophytes, horsetails and ferns all of which grew in abundance in tree-like forms in the Carboniferous period about 360-290 mya ago. Growth conditions were ideal in terms of warm temperatures and lots of rainfall and so huge forests developed. The fallen dead plant matter from these forests accumulated in low-lying areas where **coverage by swamp water made conditions anaerobic and so restricted their decomposition.** These accumulations became large and then protected and **buried by subsequent sediment deposits, where they were pressurised and heated from the Earth’s mantle, resulting in their eventual** **transformation over geological time to coal**

Question 38

When seed plants first appeared on land in a world dominated by plant groups whose evolution had been focussed on the sporophyte stage, most of their evolution and diversification and subsequent speciation involved selection in favour of strategies that served to propel their genes into future generations through evolution of various features of the gametophyte stage. Describe the five main plant traits that resulted from this selection

Answer 38

The traits that evolved included:  Gametophyte stage reduced even further to just a few cells  Heterospory – physically different male and female gametophytes that could then go on to develop into highly specialised structures (pollen and ovule respectively)  Pollen as a wind-dispersal mechanism for the male gametes  Ovules retained on the parental sporophyte and therefore protected but immobile  The seed itself which depended on the evolution of the previous 4 traits for its appearance

Question 39

Spores in the seedless plants were the principal mechanism for dispersal in all plants for the first 100 million years after land colonization. Re-write the following statement with the blanks filled in appropriately: In spore-bearing plants, spores are produced by ___osis from specialized cells on the __ploid _____ophyte and may disperse and germinate to produce a multicellular __ploid_____ophyte

Answer 39

In spore-bearing plants, spores are produced by meiosis from specialized cells on the diploid sporophyte and may disperse and germinate to produce a multicellular haploid gametophyte

Question 40

The evolution of the seed trait gave the seed plants a huge evolutionary selection advantage over spore-bearing plants in the terrestrial environment. Name two specific features of seeds, and in each case explain one evolutionary fitness benefit of that feature compared to spores

Answer 40

**Protective outer seed coat allows dormancy for days to years, until conditions are favourable for germination** **The seed’s internal nutrient-storing cells are nutrient reserves that allow the germinating seed to fully establish itself without immediate reliance on its environment** The seed’s embryo is deeply protected by both the external surface seed coat and the internal nutrient-rich enclosing tissue

Question 41

“Agriculture is in fact a brilliant if unconscious evolutionary strategy on the part of certain plants and animals to get humans to advance their interests” (Michael Pollan, Omnivores Dilemma, 2006). Write a series of logically ordered statements to explain the evolutionary biology underlying this statement using the example of maize (sweet corn; Zea mays) arising from its ancestral ancestor Teosinte (both pictured above) within the Grass family

Answer 41

 Maize evolved from an ancestral grass plant (Teosinte) that is native to C. America.  Teosinte produces a small cob at the top of the plant and each kernel is covered by a hard coating.  Ongoing selection by central American indigenous farmers of wild mutants resulted in a plant with the female (inflorescence) part moved from the shoot tip to halfway down the plant, and wrapped in a dense husk.  Subsequent farmer-derived selection resulted in dramatic increases in cob size and loss of the hard coating around the ancestral Teosinte kernels. Apparently, ‘artificial’ (i.e. human) selection of mutations in just 5 ancestral Teosinte genes achieved the transformation.  In summary, corn is an example of a plant that has evolved to become desirable to humans and hence has become a focus of agriculture, and therefore been an extraordinarily successful species in terms of global areal expansion and cover density

Question 42

Name representative species (common or scientific name) of an evergreen needle-leaf tree and of a deciduous broad-leaved tree that might be found growing on the Queen’s campus

Answer 42

**Pine**, Cedar, Spruce, Fir, **Maple**, Oak, Ash, Beech

Question 43

By considering the trade-off associated with their differences in leaf surface area/volume ratio, explain why each of these tree groups is best adapted to the soil moisture characteristics of their particular habitat-type. In your answer, be sure to clearly specify both the benefit as well as the associated cost for why evergreen needle-leaved species tend to dominate on relatively dry soils, and a specific benefit and a cost for why deciduous broad-leaved species tend to dominate on more moist soils

Answer 43

Evergreen needle-leaf trees have a relatively small leaf surface area relative to volume and the benefit of this trait is that it minimizes leaf water loss. Therefore, it allows these species to dominate in habitats where soil moisture is scarce (desiccation-resistant). The disadvantage of small leaf surface area relative to volume is that photosynthetic capacity is low, resulting in relatively slow growth rates Deciduous broadleaf tree leaves have a relatively large surface to volume ratio and the benefit of this trait is that it provides high leaf area for photosynthetic activity, and therefore these species have relatively high growth rates. However, the disadvantage is that these species have relatively high water demands and therefore generally do not grow well in habitats with habitats where soil moisture can be scarce at some times of year (such as high latitude and altitude sites)

Question 44

Some plant species have evolved specialized traits to obtain significant components of their nutrition from animals or from other plants. Explain this statement by describing three distinct examples that were discussed in lecture or in the textbook readings of plant nutrient acquisition involving other organisms

Answer 44

*** Sundew plants trap flies with sticky glues on their leaves, and then slowly digest the trapped insects by exuding digestive enzymes.** *** Pitcher plants form funnel-like shoots that trap insects and even frogs... and the slippery coating on the inside coupled with a multitude of downward point hairs prevent escape. Digestive enzymes in the funnel’s internal liquid pool at the base decompose the prey.** *Genlisea is a species featured in the textbook (Fig 37.1) and was mentioned in lecture that has highly modified underground leaves that curl over on themselves into ‘split straw’ like pipes that trap soil organisms and digest them. *** Mistletoe is an example of parasitic plant that feeds on other plants by tapping into the branch phloem tissue** * ‘Indian pipe’ plants have a root system that taps into the mycorrhizae that are functionally associated with other nearby plant species thereby gaining its carbon etc. for growth. In fact it gains sufficient carbon in that parasitic way, that it has dispensed over evolutionary time with the capacity to make chlorophyll and therefore to photosynthesize

Question 45

When a potato is stored in a cupboard or dark area for too long, the “eyes” of the potato will often produce new shoots. Based on this information, and the basic structural design of plants, explain how we know that a potato tuber is an example of a structurally specialized underground shoot and not a structurally specialized root

Answer 45

A potato is the swollen end of an underground stem (a rhizome). Stems consist of modular growing units of internode, leaf, node, and axillary meristem. Potato eyes are the axillary meristems on the main swollen underground stem, and if the potato is stored for an excessively long time, the axillary meristems will become active and produce new shoot buds (known as ‘eyes’ – that can develop into mature shoots (i.e. consisting of stems and leaves)) that are in effect branches from the original potato tuber stem

Question 46

Some plants such as grasses can have a total root surface area as much as 130 times more than the total shoot surface area. describe the likely environmental properties of a habitat-type that would promote such evolution

Answer 46

An environment that has low soil nutrients, low soil moisture, and perhaps high light, is likely to result in the evolution of a high root:shoot surface area ratio because the belowground resources are likely to be most growth-limiting. Such environments include grasslands, savannah, deserts.