Biology IB DP SL B4.2: Photosynthetic Autotrophs & Niche Concepts

Define a niche.

a species' unique way of interacting with its environment

State factors that determine the niche of a species.​

A species' niche is its entire way of life: how it gets food and water, avoids predation, reproduces, and maintains the conditions of temperature and pH required to survive.

If a species can't meet all aspects of its niche in an ecosystem, it will not survive there.

Compare niche generalists and specialists.

Generalists can survive in many environments, whereas specialists are restricted to a single environment

Compare the different oxygen requirements of obligate anaerobes, facultative anaerobes and obligate aerobes.

Obligate aerobes require oxygen at all times, so live only in oxic environments

Facultative anaerobes will use oxygen if available, but can survive without it

Obligate anaerobes die in the presence of oxygen, so live only in anoxic environments

State the energy and carbon sources utilized in photosynthesis.

cells use carbon dioxide from the air and energy from the Sun

List three groups of photosynthetic autotrophs. ​

Plants, algae, and a group of bacteria called cyanobacteria

Outline the acquisition of energy and matter by holozoic animals.

Animals are holozoic heterotrophs. This means that they ingest food and digest it internally. Holozoic organisms can also be called consumers.

Distinguish between ingestion, digestion, absorption and assimilation.

Ingestion is the in take of food. Digestion is the physical or chemical breakdown of food, so that it can be absorbed into the blood stream. Absorption is the release of digested food into the blood stream. Assimilation is the use of digested food in the organisms cells.

Outline the acquisition of energy and matter by mixotrophic protists.

Some species are not exclusively autotrophic or heterotrophic, but can use both modes of nutrition. Species like this are mixotrophs.

State an example of a mixotrophic protist.

Euglena is a single-celled organism that follows this mode of nutrition. It has chloroplasts for photosynthesis when light is available, but can also survive by eating algae or detritus (dead matter).

Euglena can survive with either mode, so it is a facultative mixotroph.

Distinguish between obligate and facultative mixotrophs.

facultative mixotrophs: can survive with either mode of nutrition alone

obligate mixotrophs: require both modes of nutrition to survive.

Outline the acquisition of energy and matter by saprotrophic organisms.

Some fungi and some bacteria are heterotrophs, but digest their food externally and then absorb the digested monomers. These are saprotrophs, also called decomposers.

Compare location of digestion in saprotrophs and detritivore animals.

Detritivores digest internally, whereas saprotrophs digest externally

List two example saprotrophic organisms.

Costasiella kuroshimae is a sea slug that eats algae but instead of digesting their chloroplasts, it keeps them in its own body tissues and absorbs the sugars they produce until they degrade.

Many carnivorous plant species like Drosera capensis (right) perform photosynthesis, but also trap insects or other small animals.

Explain why all saprotrophs are decomposers but not all decomposers are saprotrophs.

x

List the three domains of life.

Bacteria, Archaea, Eukarya

Outline the characteristics of archaea.

Archaeans are single-celled prokaryotes that live in diverse conditions, often very extreme (extreme temperatures, pH values, salinities, etc).

Compare the energy source and carbon source in chemoautotrophs and photoautotrophs.

Photoautotrophs perform photosynthesis

Heterotrophs oxidize organic compounds

Chemotrophs oxidize inorganic compounds

List extinct and extant representatives of the Hominidae family of primates.

Hominidae is the family including humans (Homo) and our closest relatives, which include chimpanzees and bonobos (Pan), gorillas (Gorilla), and orangutans (Pongo) in order of relation to us.

Outline the physiological, morphological and/or behavioral adaptations of mammalian teeth for different diet types.

Carnivores like the leopard typically have long canines for gripping and tearing, and thin, sharp molars for slicing.

Herbivores like the cow typically have broad, flattened teeth for crushing tough plant matter.

Omnivores eat a mixture of the two.

Deduce the diet of an organism given dentition patterns

While it isn't possible to study the diet of extinct species by direct observation, some deductions can be made based on dentition when fossil specimens are available. The wear patterns on teeth can also be indicative of diet as well.

All extant hominids are primarily herbivorous, but do include some animal foods (such as smaller mammals, lizards, insects, snails, and honey) in their diets, when available.

Dentition in hominids includes both flat molars for crushing, and sharp incisors for cutting food-adaptations for an omnivorous diet.

Outline the physiological, morphological and/or behavioral adaptations of leaf eating insects for feeding on plants.

Aphids have piercing mouthparts, which they use to drink the sugary sap of green stems.

Monarch caterpillars have slicing and chewing mouthparts to consume leaves.

Outline the physiological, morphological and/or behavioral adaptations of plants for resisting herbivory.

Plants acquire adaptations to resist herbivory, including:

- Thorns and other physical adaptations to deter herbivores

- Synthesis of toxic or bad-tasting chemicals in the leaves and stems

Outline the chemical, physical and/or behavioral adaptations of predators for finding, catching and killing prey.

The cheetah (Acinonyx jubatus) has long legs, a spring-like spine, and non-retractable claws that all increase its speed and handling to capture prey.

Rattlesnakes produce venom that can stop the heart of prey species, allowing the rattlesnake to consume the prey without struggle.

Wolves work together in a pack to take down prey too large for a single wolf to kill, and then share the meal.

Outline the chemical, physical and/or behavioral adaptations of prey animals for resisting predation.

The African bush elephant (Loxodonta africana) is the largest living land animal. Its large size and its tusks are both examples of physical adaptations for avoiding predation.

Poison dart frogs accumulate toxins from their diet of ants in order to make themselves toxic to other predators. Like the monarch butterfly, poison dart frogs display warning coloration-bright colors that warn predators that the frog is toxic.

Bison herding behavior has many advantages-more eyes to spot predators, more adults to protect vulnerable young, and many targets to make it more difficult for a predator to isolate a single individual

Describe examples of adaptations for harvesting light, including height,

Many tree species use the most straightforward approach: grow up toward the light, and keep growing until taller than the surrounding plants.

In order to achieve this, they have one single dominant shoot that is lignified (woody) in order to support the weight of the tree.

Describe examples of adaptations for harvesting light, including lianas

Lianas are a type of vine take root in the ground, but grow up the trunk of a tree and use it as support to reach the canopy.

The liana avoids competing for ground space and also saves the time and material it would require to build a thick, woody trunk to reach the canopy.

Describe examples of adaptations for harvesting light, including epiphyte

Epiphytes are plants that grow on other plants, rather than rooting in the soil. These are different from parasitic plants like mistletoe, which actually grow into and take nutrients from the host tree-epiphytes are only using the tree for support, not unlike a bird nesting in the tree.

Describe examples of adaptations for harvesting light, including shade-tolerance, and leaf surface area.

Plants growing in the understory simply adapt to perform photosynthesis in lower light intensity.

Plants in the understory grow thin, broad leaves to take better advantage of the bursts of light that reach the forest floor, and have different proportions of photosynthetic pigments since far-red light is more likely to pass through the canopy.

Distinguish between the fundamental and realized niche.

The fundamental niche is all of the possible habitats for a particular species.

The territory actually occupied by a species is its realized niche.

Explain competitive exclusion as a factor that can limit the distribution of a species in an ecosystem.

The competitive exclusion principle says that two species can't coexist if they occupy exactly the same niche (competing for identical resources).

Explain why two species cannot survive indefinitely in the same habitat if their niches are identical.

Species with identical niches also have identical needs, which means they would compete for precisely the same resources.

State what adaptations lessen the chances that organisms encounter competition and predation.

Organisms that can adapt to extreme niches encounter less competition and predation