Biology term 6
List the four kingdoms of eukaryotes
1. Animalia (Metazoa) 2. Plantae 3. Fungi 4. Protista
State the two groups of prokaryotes.
1. Bacteria2. Archaea
State five major classes of chordata.
1. Bony ray-finned fish 2. Amphibians 3. Reptiles 4. Birds 5.Mammals
List two difficulties in determining the natural classification of species.
1. Convergent evolution can make distantly related organisms appear superficially similar, so it is not immediately clear which groups do share a common ancestor2. Adaptive radiation can make closely related organisms appear different, making the accurate grouping of organisms based on phenotypic characteristics much more difficult
List two situations in which the reclassification of a species may be necessary.
1. Groups of species may be separated into different taxa if new evidence suggests they evolved from different ancestral species 2. Different species may be grouped into a shared taxon if new evidence suggests more recent common ancestry
State an example of homologous structures.
A common example of homologous structures is the forelimbs of vertebrates, where the wings of bats and birds, the arms of primates, the front flippers of whales and the forelegs of four-legged vertebrates like dogs and crocodiles are all derived from the same ancestral tetrapod structure.
Explain the use of a dichotomous key in the identification of a specimen.
A dichotomous key is a method of identification whereby groups of organisms are divided into two categories repeatedly.With each sequential division, more information is revealed about the specific features of a particular organism.When the organism is no longer shares its totality of selected characteristics with any organism, it has been identified
List examples of "selective pressures"
Abiotic selective pressure examples: - Change in climate - Draught - Soil nutrients Biotic selective pressures: - Competition for mates - Change in fruiting season - Competition for nesting sites
Contrast acquired characteristics with inheritable characteristics.
Acquired traits are not passed on genetically, they are traits that the individual develops over/in a lifetime that cannot be passed on to an offspringInheritable traits are passed on genetically, they come from a parent or other ancestor.
Analyze a cladogram to explain the evolutionary relationship between species.
Birds and crocodiles have a common ancestor but birds and rodents and rabbits do not
State the four major plant phyla.
Bryophyta: mosses, liverworts and hornworts Filicinophyta: ferns Coniferophyta: conifers Angiospermophyta: flowering plants
Contrast chordate and vertebrate.
Chordate: animals that possess certain key features in an embryonic state that may persist into adulthood (notochord, hollow dorsal neural tube, pharyngeal slits and a post-anal tail)Vertebrate: contain backbone composed of vertebrate → chordates are grouped into vertebrate or invertebrate
Define clade and cladistics.
Clade: a group of organisms believed to comprise all the evolutionary descendants of a common ancestor Cladistics: a method of classification of animals and plants that aims to identify and take account of only those shared characteristics which can be deduce to have originated in the common ancestor of a group of species during evolution, not those arising by convergence
Explain why the development of cladistics lead to the reclassification of some species.
Cladistics now are not only based on physical features but also DNA similarities, molecular dating, fossil/molecular dating comparison, and behavioural actions
Define cladogram and node.
Cladogram: a branching diagram showing the cladistic relationship between a number of species based on the similarities and differences between the species in a clade Node: the branching points on cladograms, indicating where species diverged
Outline the role of technological advancements in the development of cladistics.
Computer programmes were developed in the 1990s that could analyse biological sequences and construct cladograms using algorithms and based on the smallest number of changes of base or amino acid sequence. This is known as the principle of parsimony and although this method does not prove how a clade actually evolves, it can indicate the most probable sequence of divergence in clades and has resulted in some revolutions in plant and animal classification.
Explain how continuous variation across geographical ranges is evidence of evolutionary change.
Continuous variation across a geographical range of related populations matches the concept of gradual divergence. Typically this variation will be continuous and follow a normal distribution curve as the rate of change is gradual and cumulative If two populations of a species become geographically separated then they will likely experience different ecological conditions. Over time, the two populations will adapt to the different environmental conditions and gradually diverge from one another.
Define evolution
Cumulative change in heritable characteristics.
Outline the role of Charles Darwin and Peter and Rosemary Grant in the study of Galapagos finches.
Daphne Major is an island off the Galapagos archipelago. Darwin visited the Galapagos in 1835 and observed that the sizes and shapes of the finches varied according to their diet. Darwin hypothesised that an original finch species had diversified into the multiple species now found on the different islands.Since the early 1970s, the biologists Peter and Rosemary Grant have observed, tagged, and measured Galapagos finches and their environment. The Grants have documented environmental changes (i.e. drought) and how these changes favoured individuals in the population. Those individuals survived and passed on their characteristics to the next generation, illustrating natural selection in action.
Explain the effect of the selective pressure on the more and less adapted individuals in a population.
Due to the variation in the population, some individuals are better adapted and able to survive and reproduce in the presence of the selective pressure while the less adapted do not survive and reproduce as successfully. This leads to a shift in the population - more individuals with the adaptation.
Outline reasons why biological theories may change with time.
Falsification of theories with one theory bearing superseded by another- plant families have been reclassified as a result of evidence from cladistics
Identify the phyla of animal given external recognition features. Chordata
Fish: Bilateral symmetryInternal skeleton
Explain three pieces of evidence that fossils provide that evolution has occurred.
Fossils are important evidence for evolution because they show that life on earth was once different from life found on earth today. ... Paleontologists can determine the age of fossils using methods like radiometric dating and categorize them to determine the evolutionary relationships between organisms.
Contrast analogous structures and homologous structures.
Homologous structures are structures that are similar in related organisms because they were inherited from a common ancestor. These structures may or may not have the same function in the descendants. Analogous structures are structures that are similar in unrelated organisms.
Contrast analogous and homologous traits.
Homologous structures share a similar embryonic origin. Analogous organs have a similar function. For example, the bones in a whale's front flipper are homologous to the bones in the human arm. These structures are not analogous.
Use an example to explain how selective breeding has led to evolution in a species.
Horses have been selectively bred across many generations to produce variation according to a targeted function. Race horses have been bred for speed and hence are typically leaner, lighter, taller and quicker
State an example of a vestigial structure.
Human appendix, the pelvic bone of a snake, and the wings of flightless birds.
Explain the process of artificial selection using selective breeding.
Humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant males and females will sexually reproduce and have offspring together.
List the bone structures present in the pentadactyl limb structures in diagrams of amphibians, reptiles, birds and mammals.
Humerus/femur Radius/tibia Ulna/fibula Carpals/tarsals Metacarpals/metatarpals and phalanges
Outline the effect of not completing a full dose of antibiotics on the development of antibiotic resistance.
If you fail to complete a course of antibiotics, the most resistant bacteria are able to survive and will result in the bacterial population in the patient having a higher resistance to that antibiotic, as the surviving bacteria reproduce, the resulting population would not be as treatable with the same antibiotic. If the infection is passed to someone else, their infection will also be resistant to the antibiotic.
Define adaptation
In evolutionary theory, adaptation is the biological mechanism by which organisms adjust to new environments or to changes in their current environment. The idea of natural selection is that traits that can be passed down allow organisms to adapt to the environment better than other organisms of the same species.
State the classification of an animal, from domain to species.
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Primate Family: Hominidae Genus: Homo Species: sapiens Common name: Human
State the classification of a plant, from domain to species.
Kingdom: Plantae Phylum: Angiospermophyta Class: Eudicotidae Order: Ranunculales Family: Ranunculaceae Genus: Ranunculus Species: acris Common name: Buttercup
Identify the phyla of animal given external recognition features. Annelida
Mouth/anus: mouth and anusSymmetry: bilateralSkeleton: internal cavity with fluid under pressureOther external recognition features: bodies made up of many ring-shaped segments, often with bristles. Blood vessels often visible
Identify the phyla of animal given external recognition features. Mollusca
Mouth/anus: mouth and anusSymmetry: bilateralSkeleton: most have shell made of CaCO3Other external recognition features: a fold in the body wall called the mantle secretes the shell. A hard rasping radula is used for feeding
Identify the phyla of animal given external recognition features. Arhtopoda
Mouth/anus: mouth and anusSymmetry: bilateralSkeleton:external skeleton made of plates of chitinOther external recognition features: segmented bodies and legs or other appendages with joints between the sections
Identify the phyla of animal given external recognition features. Platyhelminthes
Mouth/anus: mouth onlySymmetry: bilateralSkeleton: soft, with no skeletonOther external recognition features: flat and thin bodies in the shape of a ribbon. No blood system or system for gas exchange
Identify the phyla of animal given external recognition features. Cnidaria
Mouth/anus: mouth onlySymmetry: radialSkeleton: soft, but hard corals secrete CaCO3Other external recognition features: tentacles arranged in rings around the mouth, with stinging cells. Polyps or medusae (jellyfish)
Identify the phyla of animal given external recognition features. Porifera
Mouth/anus: no mouth or anusSymmetry: noneSkeleton: internal spicules (skeletal needles)Other external recognition features: many pores over the surface through which water is drawn in for filter feeding. Very varied shapes
List sources of genetic variation
Mutation, recombination, and immigration of genes. However, recombination by itself does not produce variation unless alleles are segregating already at different loci; otherwise there is nothing to recombine.
State the source of differences between biological sequences (nitrogenous base or amino acid).
Mutations in the DNA base sequence
Define natural classification
Natural classification involves grouping organisms based on similarities first and then identifying shared characteristics. It is based on inferences concerning the phylogenetic relationships of animals- According to a natural classification system, all members of a particular group would have shared a common ancestor- This means that catural classification schemes can be used to predict characteristics shared by species within a group
Explain why natural selection can only function if there is variation in a species.
Natural selection can only occur if there is variation among members of the same species. Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species.
State that species have the ability to produce more offspring than the environment can support.
Over the course of their lifetime, species have the ability to produce far more offspring than the environmental resources (food, water, shelter) can support.
List three trends that have been observed in the development of antibiotic resistance.
Over time since antibiotics have been used, there have been changes in the resistance of the bacteria1. When new antibiotics are used, resistance will eventually establish in the population2. Resistance has spread to more species of bacteria3. The proportion of infections caused by resistant strains of bacteria has increased over time.
Relate differences in pentadactyl limb structures to differences in limb function.
Pentadactyl limb is a homologous structure: it is an example of an organ or bone with similar underlying anatomical features found in different animals. These structures support the idea that the different animals descend from a common ancestor and serve as evidence of evolution.
Explain how natural selection leads to changes in melanistic variety of insects in polluted areas.
Peppered moth: dark peppered moths became more common in polluted areas after the industrial revolution. Moths were light before and dark were rare.
Outline the characteristics of seven major animal phyla.
Porifera: fan sponges, cup sponges, tube sponges and glass sponges Cnidaria: hydras, jellyfish, corals, sea anemones Platyhelminthes: flatworms, flukes, tapeworms Mollusca: bivalves, gastropods, snails, chitons, squid, octopus Annelida: marine bristleworms, oligochaetes, leeches Arthropoda: insects, arachnids, crustaceans, myriapods Chordata: vertebrates
Outline the use of a "molecular clock" to determine time since divergence between two species.
Sequence differences accumulate gradually so there is a positive correlation between the number of differences between two species and the time since they diverged from a common ancestor.Differences in the base sequence of DNA and therefore in the amino acid sequence of proteins are the result of mutations. They accumulate gradually over long periods of time. There is evidence that mutations occur at a roughly constant rate so they can be used as a molecular clock. The number of differences in sequence can be used to deduce how long ago species split from a common ancestor
Outline the characteristics of five major vertebrate classes. Mammals
Skin has follicles with hair made of keratin- Lungs with alveoli, ventilated using ribs and a diaphragm- Tetrapods with pentadactyl limbs- Four legs in most (or two legs and two wings/arms)- Sperm passed into the female for internal fertilisation- Most give birth to live young and all feed young with milk from mammary glands- Teeth of different types with a living core- Maintain constant body temperature
Outline the reason and evidence for the reclassification of the figwort family.
Some researchers suggested that the figwort family are polyphyletic (i.e. contains more that on clade) DNA sequencing of three chloroplast genes, researchers were able to determine that there were significant differences in lineage. Therefore, the entire figwort family was reclassified into six monophyletic families.
Describe the process of gradual speciation.
Species diverge slowly over time in small steps while in the punctuated equilibrium model, a new species diverges rapidly from the parent species. The two key influencing factors on the change in speciation rate are the environmental conditions and the population size.
Define strata and palaeontology
Strata: A layer of plants or vegetation usually of the same or similar height. Palaeontology: Study of fossils
State the role of Carl Linnaeus in naming species.
Swedish naturalist and explorer who was the first to frame principles for definitiong natural genera and species of organisms and to create a uniform system for naming them (binomial nomenclature)
Define taxon and taxonomist.
Taxon: A taxonomic group of any rank, such as a species, family, or class (a scientifically classified group or entity) Taxonomist: taxonomy is the science of naming, defining (circumscribing) and classifying groups of biological organisms on the basis of any combination of the various available kinds of characteristics, such as morphological, anatomical, palynological, biochemical and genetic. A taxonomist is a biologist that groups organisms into categories.
List reasons why evolution of antibiotic resistance has been rapid.
The antibiotic resistance crisis has been attributed to the overuse and misuse of these medications (in human and agricultural applications) as well as a lack of new drug development by the pharmaceutical industry.
Outline why the binomial naming system is used in science rather than local names.
The binomial system of nomenclature provides value because:It allows for the identification and comparison of organisms based on recognised characteristics. It allows all organisms to be named accordingly to a globally recognised scheme. If local or colloquial names were used instead, it would not necessarily allow for international recognition and understanding, preventing efficient and successful collaboration.
Explain the cause of the change in frequency of traits in a population through natural selection.
The change in the frequency of traits in a population through natural selection is due to differential survival and reproduction. Better adapted individuals survive and reproduce, increasing the frequency of the adapted trait over time.
Propose a mechanism that explains the pattern found in vertebrate limb structure yet allows for the specialization of different limb functions.
The common bone structure of vertebrate limbs is due to evolution from a common ancestor. The limbs are homologous. Natural selection has lead to the same bones and joints being adapted for different uses (such as walking, running, flying, jumping, digging, swimming and grasping)
Contrast convergent evolution and adaptive radiation.
When organism leaves original niche and enter another (multiple) niche of different environments it undergoes changes to suit the new environment this is adaptive radiation. Convergent evolution is when different species of different lineage arrive in a niche and they change their body to suit common environment.
Outline the role of botanical and zoological congresses in the naming of plants and animals.
When species are discovered, they are given scientific names using the binomial system. This system is universal among biologists and has been agreed and developed at a series of international congresses. It is periodically assessed and updated at a series of international congresses which occur every 4 years. The binomial system of nomenclature provides value because:- It allows for the identification and comparison of organisms based on recognised characteristics- It allows all organisms to be named according to a globally recognised scheme- It can show how closely related organisms are, allowing for the prediction of evolutionary links- It makes it easier to collect, sort and group information about organisms.
State that only inherited characteristics can be acted upon by natural selection.
While acquired characteristics are often important and aids in survival, they are not acted on by natural selection. Only inherited characteristics can be acted upon by natural selection.
State an example of recognizably different populations of the same species across a geographical range.
Yarrow plants, height depends on homologous structures.
State an example of analogous and homologous traits.
bones in a whale's front flipper are homologous to the bones in the human arm. These structures are not analogous. A butterfly or bird's wings are analogous but not homologous. Some structures are both analogous and homologous: bird and bat wings are both homologous and analogous.
Define pentadactyl limb.
having five digits on each hand or foot pentadactyl mammals.It evolved from the paired fins of primitive fish as an adaptation to locomotion on land and is not found in modern fish.
Outline the relationship between time, evolutionary relationships and biological sequences (nitrogenous base or amino acid)
vidence for which species are part of a clade can be obtained from the base sequences of a gene or the corresponding amino acid sequence of a protein.The most objective evidence comes from the base sequence of genes or amino acid sequence of proteins. Species that have a recent common ancestor can be expected to have a few differences in base or amino acid sequence. Conversely, species that might look similar in certain respects but diverged from a common ancestor tens of millions of years ago are likely to have many differences.
Outline the characteristics of five major vertebrate classes. Reptiles
- Impermeable skin covered in scales of keratin- Lungs with extensive folding to increase the surface area- Tetrapods with pentadactyl limbs- Four legs (in most species)- Sperm passed into the female for internal fertilisation- Female lays eggs with soft shells- Teeth all of one type, with no living parts- Do not maintain constant body temperature
Outline the characteristics of five major vertebrate classes. bony ray-finned fish
- Scales which are bony plates in the skin- Gills covered by an operculum, with one gill slit- No limbs- Fins supported by rays- Eggs and sperm released for external fertilisation- Remain in water throughout their life cycle- Swim bladder containing gas buoyancy- Do not maintain constant body temperature
Outline the characteristics of five major vertebrate classes. Birds
- Skin with feathers made of keratin- Lungs with para-bronchial tubes, ventilated using air sacs- Tetrapods with pentadactyl limbs- Two legs and two wings- Sperm passed into the female for internal fertilisation- Female lays eggs with hard shells- Beak but no teeth- Maintain constant body temperature
Outline the characteristics of five major vertebrate classes. Amphibians
- Soft moist skin permeable to water and gases- Simple lungs with small folds and moist skin for gas exchange- Tetrapods with pentadactyl limbs- Four legs when adult- Eggs and sperm released for external fertilisation- Larval stage that lives in water and adult that usually lives on land- Eggs coated in protective jelly- Do not maintain constant body temperature
Explain two specific advantages of natural classification.
1. Identification of species is easier. If a specimen of an organism is found and it is not obvious which species it is, the specimen can be identified by assigning it first to its kingdom, then the phylum, class, and so on down to species level. Dichotomous keys can be used to help with this princess2. Because all of the members of a group in a natural classification have evolved from a common ancestral species, they inherit similar characteristics. This allows prediction of the characteristics species within a group
List the hierarchy of taxa, from largest to smallest.
1. Kingdom 2. Phylum 3. Class 4. Order 5. Family 6. Genus 7. Species
List examples of adaptations.
1. Structural: physical differences in biological structure (e.g. neck length of a giraffe, the structure of a bird's beak diet and method of feeding)2. Behavioural: differences in patterns of activity (e.g. opossums feigning death when threatened)3. Physiological: variations in detection and response by vital organs (e.g. homeothermy, colour perception)4. Biochemical: differences in the molecular composition of cells and enzyme functions (e.g. blood groups, lactose tolerance)5. Developmental: variable changes that occur across the lifespan of an organism (e.g. patterns of ageing/senescence)
State three rules of binomial nomenclature formatting.
1. The genus name is always written first2. The genus name must be capitalised3. The specific epithet (species) is never capitalised- The entire two-part name must be written in italics (or underlined when handwritten)
Explain how natural selection leads to changes in the beaks of Galapagos finches with changes in weather conditions.
1. There is an overproduction of finches in the population 2. The finches have variation in their beak shape 3. There is a selective pressure, such as a drought causing a shortage of small seeds 4. There is differential survival and reproduction: birds with the larger, stronger beaks are able to crack the larger seeds. Larger beaked birds are able to eat the seeds, providing energy to survive and reproduce 5. In just a generation, the frequency of the larger beak increases in the population
Use an example to illustrate the potential for overproduction of offspring in a population.
An example of overproduction is sea turtles, which can lay about 100 eggs in a clutch with only about one hatchling surviving to reproduce
Outline how computer programs analyze biological sequence data to create cladograms.
Analysis of cladograms to deduce evolutionary relationships.Multiple alignment software compares DNA or protein sequences for similarities and differences.Closely related species are expected to have a high degree of similarity in their molecular sequence.Clustal Omega is a free online tool that will align multiple DNA amino acid sequences for comparison.
Define vestigial structure
Anatomical features that are fully developed in one group of organisms but are reduced and may have no function in similar groups
Outline how a "selective pressure" acts on the variation in a population.
Any cause that can reduce reproductive success in a portion of a population is called a selective pressure. Selective pressures can be biotic (i.e. fighting others for access to a mate) or abiotic (i.e. a change in the climate). Selective pressures affect individuals differently - with individuals with beneficial variations in behaviour or physical traits (better adapted) able to survive and produce more offspring.
List the three domains of life.
Archaea → prokaryotic cells lacking a nucleus and consist of the extremophiles Bacteria → prokaryotic cells lacking a nucleus and consist of the common pathogenic forms Eukarya → eukaryotic organisms that contain a membrane-bound nucleus
Compare the reproductive success of better and less adapted individuals in a population.
Better individuals survive and are able to reproduce to pass on the adapted characteristic to their offspring. Less adapted individuals have a lower survival rate, and therefore a lower reproductive rate. Over generations, the frequency of the adapted trait in the population will increase.
Discuss the use of cladograms as hypotheses of evolutionary relationships.
The pattern of branching in a cladogram is assumed to match the evolutionary origins of each species. The sequence of spits at nodes is therefore a hypothetical sequence in which ancestors of existing clades diverged. If two clades on a cladogram are linked at a node, they are relatively closely related. If two species are only connected via a series of nodes, they are less closely related.Although cladograms can provide strong evidence for the evolutionary history of a group, they cannot be regarded as proof. Cladograms are constructed on the assumption that the smallest possible mutations occurred to account for the current base or amino acid sequence differences. Sometimes this assumption is incorrect.
Define binomial nomenclature.
The system of nomenclature in which two terms are used to denote a species of living organism, the first one indicating the genus and the second the specific epithet (species).
State an example of analogous structures.
The wings of an insect, bird, and bat would all be analogous structures: they all evolved to allow flight, but they did not evolve at the same time, since insects, birds, and mammals all evolved the ability to fly at different times.
Outline differences between the three domains of life.
Upgrade: Free 7-day trial 4 IB Biology SL: Unit 5: Evolution and Biodiversity (2020) Leave the first rating STUDY Flashcards Learn Write Spell Test Play Match Gravity List the three domains of life. Archaea → prokaryotic cells lacking a nucleus and consist of the extremophilesBacteria → prokaryotic cells lacking a nucleus and consist of the common pathogenic formsEukarya → eukaryotic organisms that contain a membrane-bound nucleus Outline differences between the three domains of life. Histones associated with DNA:- Archaea → proteins similar to histones bound to DNA- Bacteria → absent- Eukarya → presentPresence of introns:- Archaea → present in some genes- Bacteria → rare or absent- Eukarya → frequentStructure of cell walls:- Archaea → not made of peptidoglycan- Bacteria → made of a chemical called peptidoglycan- Eukarya → not made of peptidoglycan; not always presentCell membrane differences:- Archaea → glycerol-ether lipids; unbranched side chains; l-form of glycerol- Bacteria → glycerol-ester lipids; unbranched side chains; d-form of glycerol- Eukarya → glycerol-ester lipids; unbranched side chains; d-form of glycerol
Outline an example of a species (or group of species) which were reclassified when new evidence was discovered.
Using taxonomic procedures, humans are assigned to the order Primates and the family Hominidae. There has been much debate which, if any, of the great apes to include in this family. Originally all the great apes were placed in the Pongidae family, but research has shown that chimpanzees and gorillas are closer to humans than to orangutans so should be in the same family as humans. This would leave just orangutans in the Pongidae. Most evidence suggests that chimpanzees are closer to gorillas than humans, so if humans and chimpanzees are placed in different genera, gorillas should also be placed in a separate genus.
Define variation
Variation, in biology, any difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences (genotypic variation) or by the effect of environmental factors on the expression of the genetic potentials (phenotypic variation).
Outline the differences between the four major plant phyla in regard to external recognition features. Bryophytes
Vegetative organs: rhizoids but no true roots. Some with simple stems and leaves; others have only a thallus Vascular tissue: no xylem or phloem Cambium: no cambium; no true trees and shrubs Pollen: pollen is not produced Ovules: no ovaries or ovules Seeds: no seeds Fruits: no fruits
Outline the differences between the four major plant phyla in regard to external recognition features. Filicinophytes
Vegetative organs: roots, stems and leaves are usually present Vascular tissue: xylem and phloem are both present Cambium: no cambium; no true trees and shrubs Pollen: pollen is not produced Ovules: no ovaries or ovulesSeeds: no seeds Fruits: no fruits
Outline the differences between the four major plant phyla in regard to external recognition features. Angiospermophytes
Vegetative organs: roots, stems and leaves are usually present Vascular tissue: xylem and phloem are both present Cambium: present in conifers and most angiosperms, allowing secondary thickening of stems and roots and development of plants into trees and shrubs Pollen: pollen is produced by anthers in flowers Ovules: ovules are enclosed inside ovaries in flowers Seeds; seeds are produced and dispersed Fruits: fruits are produced for dispersal of seeds by mechanical, wind or animal methods
Outline the differences between the four major plant phyla in regard to external recognition features. Coniferophytes
Vegetative organs: roots, stems and leaves are usually present Vascular tissue: xylem and phloem are both present Cambium: present in conifers and most angiosperms, allowing secondary thickening of stems and roots and development of plants into trees and shrubs Pollen: pollen is produced in male cones Ovules: ovules are produced in female cones Seeds: seeds are produce and dispersed Fruits: no fruits
