Unit 1 Review Flashcards
The biological species definition has some
weaknesses. In each instance below, identify
the weakness and suggest a modification of
the species definition that would allow the
organisms to be defined as a unique species.
(a) Mules, the offspring of a male donkey and
a female horse
-can’t reproduce
-the definition could be changed to hybrids being able to reproduce
The biological species definition has some
weaknesses. In each instance below, identify
the weakness and suggest a modification of
the species definition that would allow the
organisms to be defined as a unique species.
(b) Asexually reproducing prokaryotes such
as bacteria
don’t reproduce sexually
-the definition can change to organisms being able to reproduce asexually
The biological species definition has some
weaknesses. In each instance below, identify
the weakness and suggest a modification of
the species definition that would allow the
organisms to be defined as a unique species.
(c) Extinct dinosaurs and prehistoric mammals
gone extinct
-the definition can change to include extinct animals
Given that bacteria can reproduce very quickly,
what prevents them from overpopulating the
world?
their populations do not grow to this size due to limited food and space
Why would it be easy to mistake a fungus-like
protist for a fungus? How are the two types of
organisms different?
looks similar to actual fungus
The fungus-like protists are unicellular. They were originally called fungi because they produce sporangia.
These protists differ from fungi in that their cell walls have cellulose rather than chitin.
Fungus-like protists also generally do not have divisions between their cells like fungi do.
fungus like protist
feeds on decaying organic matter and some are decomposers that live mainly on decaying organic matter and water moulds
animal like protist
heterotrophs that capture and ingest food
some engulf food with pseudopodia, or use cilia to get their food
plant like protist
autotrophs
some contain chloroplasts (photosynthesis)
some play important parts in water ecosystems (phytoplankton form the base of food chains for most other aquatic organisms)
Fungi cannot produce their own food or move
to capture food. What adaptations allow fungi
to quickly absorb food when they come in
contact with a source of nutrients?
Fungi absorb nutrients from the environment through mycelia. The branching mycelia have a high surface-area-to-volume ratio which allows for efficient absorption of nutrients
Suppose you observe an animal that does not
have a distinct head. What type of symmetry
and lifestyle do you think it might have?
no cephalization… radial symmetry
-sessile, can’t move–> probably live in water and rely on transport of food by water currents
Why are some pollutants more harmful to
organisms near the top of the food chain than
those near the bottom that are directly exposed
to the pollutants?
bioaccumulation…pollutant builds up in tissues
The herbicide atrazine, for example, accumulates in
sublethal doses in amphibians, even changing
the sex of species, such as leopard frogs.
As top predators in the food chain eat the tainted animals, lethal doses of pesticides build up in their tissues
Suppose a marine biologist returns from
exploring the deep-sea and presents the
scientific community with an unknown animal.
What are some characteristics scientists could
use to determine in which phylum the animal
might belong?
true tissues
radial vs bilateral symmetry
protostomes vs deuterostome
vertebrate vs invertebrate
The sea cucumber has deuterostome
development and no appendages. The
bumblebee has protostome development and
appendages. Humans have deuterostome
development and appendages, such as arms
and legs. Which of the two organisms are
more closely related? Explain your answer.
sea cucumbers and humans are more closely related because we’re both deuterostomes and were formed the same way
What role does fungi play in ecosystems?
Fungi have the ability to transform nutrients in a way that makes them available for plants.
Some fungi are decomposers which mean that they break down plant and animal debris, thus cycling nutrients and increasing their availability in the soil.
Antibiotics are medicines that destroy microorganisms that cause disease and infections.
Humans often produce antibiotics from
chemicals naturally produced by organisms.
Fungi cultivated by leaf cutter ants produce
an antibiotic crucial to the survival of the
ant colony. Why might organisms other than
humans produce antibiotics?
They are produced in nature by soil bacteria and fungi.
This gives the microbe an advantage when competing for food and water and other limited resources in a particular habitat, as the antibiotic kills off their competition (antibiotics kill bacteria)
