Chapter 18 Biodiversity Essay QS Flashcards
Outline the characteristic features of organisms in the domain Bacteria. [8]
- no nucleus
- circular DNA
- histone-like proteins associated with DNA
- no membrane-bound organelles
- named example of absent organelle (mitochondria, endoplasmic reticulum)
- 70S ribosomes
- cell wall made of, peptidoglycan / murein
- (reproduce by) binary fission
- unicellular
- spherical / rod / spiral / comma / corkscrew, shape OR may form, pairs / tetrads / strings / filaments / clusters / palisades
- size detail: 1 - 5 micrometres
- AVP; (other structural feature)
- AVP; (other non-structural feature)
Outline the characteristic features of organisms in the domain Eukarya. [8]
- nucleus
- (double) membrane-bound organelles
- 80S ribosomes
- chloroplasts / mitochondria, have 70S ribosomes
- linear DNA
- DNA associated with, histones / proteins
- chloroplasts / mitochondria, DNA is circular
- unicellular, colonial & multicellular
- cells divide by mitosis
- reproduction can be asexual & sexual
- AVP
Compare the characteristic features of the domains Eukarya & Bacteria. [8]
Eukarya VS Bacteria:
- nucleus VS no nucleus
- linear DNA VS circular DNA / plasmid
- histone proteins associated with DNA VS no histone proteins
- (double) membrane-bound organelles VS no membrane-bound organelles
- 80S ribosomes VS 70S ribosomes
- cell wall sometimes present VS cell wall always present
- cell wall (if present) made of, cellulose / chitin VS cell wall made of peptidoglycans
- cells divide by mitosis VS cells divide by binary fission
- (can be) multicellular VS unicellular
- AVP; e.g. differences in flagellum structure
It has been stated that the kingdom Protoctista can be described as a very diverse group of organisms that share only a few common features. Discuss the ways in which members of the kingdom Protoctista are similar to each other & ways in which they differ. [7]
Similarities:
- eukaryotic (cells)
- detail of eukaryotic cell; e.g. nucleus / linear DNA
- / chromosomes associated with histones
- / (named) membrane-bound organelles / 80S
- ribosomes
Differences:
- single-celled or colonial / multicellular
- autotrophic or heterotrophic
- motile or unable to move
- cell wall or no cell wall
- vacuole or no vacuole
- different life cycles
Compare the characteristic features of members of the kingdoms Fungi & Animalia. [7]
Fungi & Animalia:
1. eukaryotic cells
2. 3. details of eukaryotic cells, (e.g. nucleus / linear DNA / chromosomes / histones / 80S ribosomes / (named) membrane-bound organelles
4. heterotrophic / described
5. ref. to glycogen
Fungi only:
6. some unicellular
7. hyphae / mycelium
8. multinucleate parts
9. ref. to spores
10. cell walls made of chitin
Animalia only:
- multicellular
- specialised cells
- differentiated into, tissues / organs
- some motile
- (some cells have) cilia / flagella
Describe the main features of an organism belonging to the plant kingdom. [8]
- multicellular
- differentiated cells
- (most) have, vascular tissue / xylem & phloem
- eukaryotic (cells)
- ref. meristems
- (most) are not motile
- motile gametes only in mosses & ferns
- autotrophic nutrition / photosynthesis
- (cells have) chloroplasts
- large / central, vacuole
- walls made of cellulose
Viruses are not included in the three domain classification system as they have different features from most organisms. Describe the features of viruses. [8]
- not cellular
- contain, nucleic acid / genetic material / DNA / RNA (core)
- DNA may be, single- / double-, stranded
- (core surrounded by) protein coat / capsid / capsomeres
- may have, external / lipoprotein, envelope / membrane
- 20 - 750 nm
- obligate parasites
- reproduced / replicated, in / by, host cells
- disease-causing / pathogenic
- no, metabolism / respiration / nutrition / excretion / growth
- cannot move / immobile
- have, proteins / enzymes, to help, infection / replication
- (highly) specific to host (cells)
- not living
Explain what is meant by the terms ecosystem & niche. [7]
Ecosystem:
- self-contained community of interacting organisms (& the environment they live in and interact with) (3 marks)
- there are both living & non-living / biotic & abiotic components within an ecosystem
- there is a flow of energy within an ecosystem & nutrients within it are recycled
Niche:
- role of organism / how it fits in, (in an ecosystem)
- (including) where it lives
- how it obtains energy / ref. trophic level
Describe the sampling techniques that could be used to measure the distribution & abundance of organisms in a habitat. [8]
- random (sampling)
- (frame) quadrat
- use cover scale
- estimate % cover
- species frequency
- systematic sampling
- line / belt, transect
- sample at set distances
- mark-release-capture
- method of, capture / marking
- returned to habitat & left
- population estimate = (no. of individuals in first sample - no. of individuals in second sample) / no. of individuals marked in 2nd sample
- appropriate mathematical / statistical technique
Describe how random sampling can be used to assess the distribution & abundance of plants in an area. [6]
- area marked out as a grid
- co-ordinates obtained using a random number generator
- quadrats used
- placed at random co-ordinates
- ref. to size of quadrat
- species identified within quadrat
- % cover / count number within quadrat
- repeat sampling
- AVP, e.g. large sample size, means calculated, method of calculating abundance & richness
Using examples, explain why species may become extinct. [7]
- environment changes
- species cannot adapt (fast enough)
- climate / temperature / sea level, change
- extinct species / species at risk
- (named) habitat, degradation / loss
- extinct species / species at risk
- hunting by humans / poaching / (over)fishing
- extinct species / species at risk
- AVP
Explain the need to maintain biodiversity in an ecosystem such as a tropical rainforest. [7]
- cultural / aesthetic / leisure, reasons
- moral / ethical, reasons (e.g. right to exist / prevent extinction)
- resource material (e.g. wood (for building) / fibres for clothes / food for humans / (herbal) medicine)
- (eco)tourism
- economic benefits
- ref. resource / species, may have use in future / AW (e.g. medical use)
- maintains, food webs / food chains
- nutrient cycling
- protection against erosion
- climate stability
- maintains, (large) gene pool / genetic variation
- scientific research
Describe the methods used to conserve endangered animal species. (7)
- place in zoos
- protected against, disease / predation
- captive breeding programme
- ref. assisted reproduction / cloning / sperm banks
- released into wild
- ref. national parks / reserves
- rangers patrol parks
- human access restricted
- controlled agriculture
- controlled industry
- visitor centres / education
- habitat / breeding sites, protected
- banning sale of protected animals or their products
- banning hunting
Discuss the use of assisted reproduction techniques in the conservation of endangered mammal species. (7)
- useful for species where reproduction is difficult
- example; e.g. from habitat fragmentation / reproductive physiology
- increases the rate of, reproduction / offspring production
- IVF
- hormone treatment / superovulation
- (many) oocytes harvested
- (oocytes) mixed with sperm
- embryos placed in uterus
- surrogacy
- detail; e.g. use a similar species / non-rare breed
- ref. to embryo transfer
- AVP; e.g. embryo splitting; cryopreservation of sperm; artificial insemination
Discuss the methods used in breeding programmes for endangered animal species & outline the problems that may occur with these programmes. (8)
Methods:
- provide as natural an environment as possible / described
- storage of, sperm / egg / gametes OR sperm banks
- artificial insemination / IVF
- embryo transfer / surrogate mothers
- can monitor, health of mother / development of foetus
- (international) cooperation between zoos
- genetic records kept
- release into the wild
Problems:
- may be stress in captivity
- mate may be rejected
- reproductive cycles may be disrupted (in captivity)
- named problems with release, e.g.: difficulty in finding food / may not integrate into groups / more susceptible to disease / very little natural habitat left to release animals into (2 points)
