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From reading accessible information about tubers and taproots I recognize that the main differences between tubers and taproots (as well as a fibrous root system) are:
- Different nutrient synthesis: Tubers contain less complex sugars than taproots
A possible third difference
As one who prefer a vegan diet in general I read a lot about B12; in many places (for example) Wikipedia, something like this was written:
In the past, humans got Vitamin B12 from eating the roots of "short plants" that absorbed the vitamin from bacteria which produced it near to their roots.
This led me to assume that either tubers or taproots (as well as a fibrous root system) have Vitamin B12 absorption by dedicated receptors and if one has it and the other doesn't here is yet another difference.
An interesting side note: Tubers are always under soil while roots in general, aren't necessarily; as with aerial roots.
What are the main differences between tubers and taproots?
They are actually completely different plant parts: a taproot is the central root of a taproot-system plant while a tuber is an engorged modified underground stem called a rhizome.
A morphological and functional difference between rhizomes and roots are that rhizomes (being modified stems) have nodes, while roots never do.
- Note: a node = the location on a plant stem where buds (leaves, flowers, stem branches) initiate
According to "Plant Identification Terminology: An Illustrated Glossary" (Harris & Harris, 2001)1:
Taproot. The main root axis from which smaller root branches arise; a root system with a main root axis and smaller branches… Figure 1273
Root. The portion of the plant axis lacking nodes and leaves and usually found below ground.
Tuber. The thickened portion of a rhizome bearing nodes and buds; underground stem modified for food storage. Figure 1366
Rhizome. A horizontal underground stem. Figure 1052
See here for a photo of a potato plant showing a young tuber and an older tuber growing on the end of a rhizome.
According to here:
Tubers-are swollen regions of stems that store food for subsequent growth. The potato is an example. It is a stem because it has many nodes called eyes with spaces between eyes known as internodes. Potato tubers develop at the end of swollen underground stem structures, rhizomes.
Eyes of potatoes are really axillary buds which contain several small buds at each site. These buds can expand to form shoots which grow on to make whole plants.
You can explore histologic, anatomic, and physiologic differences of stems vs roots more generally to understand broader differences between the two plant parts.
Proença & Sajo (2008)2 discuss root and rhizome anatomy in select bromeliads.
Figure 1 from Hernán et al. (2014) shows how the vascular and various tissue layers can differ quite a bit between roots and rhizomes on the same plant.
Some structures characteristics of roots (e.g., casparian strips) can also occur in rhizomes. (E.g., see Lersten 19974.
Unlike potatoes (which are tubers), sweet potatoes (Ipomoea batatas) are actually a modified root called tuberous roots
1 Harris, J.G. and Harris, M.W., 1994. Plant identification terminology: an illustrated glossary (No. QK9 H37 2001). Utah: Spring Lake Publishing.
2 Proença, S.L. and Sajo, M.D.G., 2008. Rhizome and root anatomy of 14 species of Bromeliaceae. Rodriguésia, 59(1), pp.113-128.
3 Hernán, G., Varela, B.G., Fortunato, R.H. and Wagner, M.L., 2014. Pharmacobotany of two Valeriana species (Valerianaceae) of Argentinian Patagonia known as “Ñancolahuen”. Lat Am J Pharm, 33(6), pp.891-6.
4 Lersten, N.R., 1997. Occurrence of endodermis with a casparian strip in stem and leaf. The Botanical Review, 63(3), pp.265-272.
What Is A Tuber – How Tubers Differ From Bulbs And Tuberous Roots
In horticulture, there is certainly no shortage of confusing terms. Terms like bulb, corm, tuber, rhizome and taproot seem to be especially confusing, even to some experts. The problem is the words bulb, corm, tuber and even rhizome are sometimes used interchangeably to describe any plant that has an underground storage unit that helps the plant survive periods of dormancy. In this article, we will shed some light on what makes a tuber a tuber, what are tuberous roots and how tubers differ from bulbs.
What Are the Two Main Types of Root Systems?
The two main types of root systems are taproots and fibrous roots. A taproot consists of a single large, central root with smaller side roots, while fibrous root systems consist of networks of many small roots.
Common examples of plants with taproots include carrots and beets. As plants with taproots grow larger, their roots grow straight down into the ground in order to gain access to more water and nutrients. Shorter, thinner roots, known as lateral roots, protrude from the sides of some taproots to help hold them in the ground. Lateral roots arise from the pericycle, which is the central portion of the root, allowing the water that they absorb to be passed directly into the main root and up to the rest of the plant.
Examples of plants with fibrous root systems include grasses and trees. As these plants grow, they expand their root systems over the surface of the land, rather than reaching further down. Networks of fibrous roots can be extremely extensive the roots of one grass plant may be more than 100 miles long when laid end-to-end.
In addition to fibrous roots and taproots, there is also a third type of roots known as adventitious roots. These are roots that emerge from an above-ground portion of the plant, such as from a stem or leaf. Plants with adventitious roots also have either a taproot or fibrous root system in addition to their adventitious roots.
New bulbs often form around the original bulb. These are called offsets and develop from buds within the base of the original bulb to produce new plants. Tubers do not grow from a single point. Instead, the buds – sometimes referred to as eyes – develop over the surface of the tuber, so stems can appear from the sides as well as the ends. New plants can be grown from tuber cuttings containing buds or eyes, or from seeds.
True bulbs are either tunicate or non-tunicate. Tunicate bulbs have a papery tunic that protects the scales from injury and drying. Tulips, hyacinths, daffodils and alliums are tunicate bulbs. A non-tunicate bulb does not have a tunic to protect the scales, so these bulbs must be kept consistently moist before planting. A lily is an example of a non-tunicate bulb.
Tubers also come in two types: stem or tuberous root. Stem tubers are formed from thickened stolons or rhizomes. Shoots are produced on the top sides of the tuber that later grow into stems and leaves. The undersides of stem tubers produce roots. Tuberous roots are also referred to as storage roots and are a lateral root that enlarges to function as a storage organ. The enlarged area of this type of tuber may form at the end of the root or the middle, or it may encompass the entire root. Potatoes are root tubers, while begonias are stem tubers.
Differences Between Taproot And Fibrous (Adventitious) Roots In Tabular Form
|Points of Comparison||Taproot||Fibrous root|
|Origin||Develops from the radicle of the seed.||Develops from the stem tissue of the plant base.|
|Appearance||Generally found in dicotyledonous plants.||Generally found in monocotyledonous plants.|
|Thickness||Taproot is the thickest while secondary and tertiary taproots have a much reduced thickness.||Fibrous roots on the other hand, have the same thickness.|
|After germination||After germination of a seed, the first root that emerges from it is known as radical or primary root. The radical eventually forms the taproot.||The fibrous root system begin as a taproot from the radicle, but as the plant grows, the radicle degenerates and no primary root is seen.|
|Examples||Conifers, carrots, dandelions, poison ivy, annual flowers, radishes and beetroot.||Onions, tomatoes, lettuce grasses, lilies, palms, corn, beans, peas, sweat potatoes, rice and wheat.|
|Anchorage||Taproot system has one main root called taproot and it produces lateral branches called secondary roots which in turn produce tertiary roots.||In Adventitious root system, a number of main root develop at one point or spot.|
|Branching||Secondary and tertiary roots grow off from the main taproot and create a tap root system.||Fibrous roots do not branch like the way taproot does, they are a clump of roots derived from the plant base.|
|Growth||Taproot is long and grows vertically deep in to the soil.||Fibrous roots are short and most of them grow horizontally in the soil.|
|Lifespan||Has a long lifespan.||Has a short lifespan.|
|Absorption of Water||Has ability to absorb water from deeper layers of the soil.||Fibrous root system does not have such ability.|
|Holding of Soil Particles||Taproot doesn’t hold soil particles together.||Fibrous root holds many soil particles together at the surface of the soil, hence preventing soil erosion.|
|Storage||Acts as storage organ for food.||Do not store anything.|
|Occurrence||A single plant usually has a one taproot.||A single plant can have hundreds of fibrous roots.|
Similarities between Taproot and Adventitious (Fibrous) root
- Both have the main function of absorption of water and nutrients from the soil.
- Both are found in higher plants.
- Both act as plant anchorage by holding the plant firmly with the soil.
- Both taproots and fibrous roots are true root types.
- Both grow underground.
What is the main difference between taproot and fibrous root system?
Taproot develops from the radicle of the seed whereas fibrous root develops from the stem tissue of the plant base.
Difference Between Alocasia and Colocasia
Alocasia and colocasia, better known as ‘elephant ears’, belongs to the same family of Araceae. Though they belong to the same family, they have many striking differences between them.
One of the main differences that people do not notice is in the difference in the characteristics of the leaves. The leaves of alocasia are seen to stand in a horizontal direction. The tips are pointed in the upward direction. Moreover, the leaves of alocasia have a shiny surface and come with an extended corm.
The leaves of Colocasia are seen to droop downwards. In contrast to Alocasia, the leaf tip of colocasia points downwards. The corm of colocasia has a less rounded shape.
When Alocasias grows well in well drained soil and shady places, the Colocasia plants grows more in sun light and in lands with ample water. Another difference can be seen in the placement of petiole. When the petiole of Alocasia is attached to the notch, the petiole in colocasia is attached a bit down the notch.
Another significant difference can be seen in the female flowers of the two plants. The placenta is Alocasia plant is basal. The stem and the ovaries are attached to this placenta along the interior base. On the other hand, the placenta in colocasia is seen next to the inner side. The stem and the ovaries are connected with the placenta through the interior sides of ovary.
One can also differentiate between Alocasia and Colocasia by looking at the tuber. The Colocasia tubers are banded, large and swollen. On the other hand, the tubers of Alocasia are thin and longer.
The leaves of alocasia are seen to stand in a horizontal direction. The leaves of Colocasia are seen to droop downwards.
The tips of alocasia leaves are pointed in the upward direction. In contrast to Alocasia, the leaf tip of colocasia points downwards.
When the petiole of Alocasia is attached to the notch, the petiole in colocasia is attached a bit down the notch.
When Alocasias grows well in well drained soil and shady places, the Colocasia plants grows more in sun light and in lands with ample water.
The Colocasia tubers are banded, large and swollen. On the other hand, the tubers of Alocasia are thin and longer.
Alocasia plants have an extended corm whereas the corm of colocasia is less rounded.
What are the main differences between tubers and taproots? - Biology
Biology Paper 3 (Practical), WASSCE (SC), 2017
LIST OF SPECIMENS
Specimen A - Winged termite.
Specimen B - Maggot (freshly procured).
Specimen C - Adult butterfly with open wings.
Specimen D - Caterpillar (freshly procured).
Specimen E - Grasshopper.
Specimen F - Carrot with leaves attached (freshly procured).
Specimen G - Irish potato.
Specimen H - Adult mosquito.
Specimen J - Adult cockroach.
Specimen Q - Housefly.
Specimen R - Earthworm (dead, freshly procured in a Petri dish containing water).
Specimen S - cross section of unripe mango fruit.
Specimen T - Cross section of tomato fruit.
- (a) State three observable features of biological importance in:
(i) specimen F [3 marks]
(ii) specimen G. [3 marks]
- (i) Classify specimens F and G as either stem tuber or root tuber. [2 marks]
(ii) Give two reasons each for the answers in 2(b)(i). [4 marks] Study specimens H and J carefully and use them to answer questions 2(c) and 2(e).
- Classify specimens H and J into the class to which both belong. [1 mark]
- (i) State four observable differences between specimens H and J. [4 marks]
(ii) State four observable similarities between specimens H and J. [4 marks]
- (i) State the feeding habits of each of specimens H and J. [2 marks]
(ii) Name two observable features used for feeding in specimen J. [2 marks]
This question was poorly attempted. Some candidates could not state the observable features of biological importance of specimen F. Some candidates could state the observable similarities between specimens H and J. Most candidates could not also state the feeding habits of specimen H but could state for specimen J.
The expected answers are:
- Observable features of biological importance in
- Main root/tap root/swollen/root tuber
- Presence of lateral roots
- Presence of short stem (green)
- Presence of foliage leaves
- Part of main root tapering.
Specimen G/Irish potato
(ii)Reasons for classificationSpecimen F/Carrot
- Has a reduced stem (above the swollen tap root).
- presence of scale leaves/leaf
(ii) Similarities between specimens H/adult mosquito and J/adult cockroach
- Presence of a pair of compound eyes
- Body is divided into three divisions/head, thorax and abdomen
- Three pairs of/six (walking) legs
- Presence of jointed appendages
- Presence of a pair of membraneous wings
- Presence of a pair of antennae
- Both have exoskeleton made of chitin
(i)Feeding habit of
Specimen H/adult mosquito
Piercing and sucking
Specimen J/adult cockroach
Biting and chewing
(ii)Observable features used for feeding in specimen J/adult cockroach
Mandible maxillae labium labrum
NECO Practical Biology Questions and Answers
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Today’s NECO Biology Practical Answers: (2020 Answers)
Specimen A is yam tuber
Specimen B is cassava tuber
Specimen C is quadrant
Specimen D is insect net
Specimen E is rain guage
Specimen F is rice grain
Specimen G is dry groundnuts seed
Specimen A is propagated from small tubers
Specimen B is propagated by stem
Specimen F is propagated by seeds
Specimen C is used for for study of the distribution of an item over a large area.
Specimen D is used for prevention against insects
Specimen E is used to measure the precipitating rain
Diagram of insect net.
(i)The surface of B turn blue-black
(ii)starch is present
Specimen F grains (cereals)
Specimen G puises (legume)
(i)The paper appears translucent
(ii) Specimen G contain fat and oil or fat and oil is present in specimen G
Specimen H is contour feather
Specimen I is quill feather
Specimen J is Filoplume
Specimen K is millipede
Specimen L is centipede
(i)They provide insulation to birds
(ii)Feathers allow for flight
(iii)Feathers are used for defense
(iv)Feathers are used for camouflage
(i)Specimen H serve as aerodynamic
devices for flight
(ii)Specimen J are used principally as insulation, to conserve body heat.
Specimen K belong to the class Diplopoda
Specimen L belong to the class Chilopoda.
In tabular form
(i)millipedes are more rounded.
(ii)Millipedes have two sets of legs per segment positioned directly under their body.
(i)centipedes have a flatter body
(ii)Centipedes have one set of legs per segment positioned on the side of their body.
Specimen M is Grasshopper
Specimen N is spider
Specimen O is Larva (house fly)
Specimen P is Larva ( mosquito)
Specimen Q Flame of The forest flower
Specimen R hibicuss flower.
NECO Bio Practical Practice Questions
The questions below are for practice not the 2020 Biology Practical questions.
1. (a) (i) Phylum of specimens C/Butterfly and E/Grasshopper: Arthropoda
(ii) Reasons for the answer in 1 (a)(i): (I) Metameric segmentation/segmented bodies: (II) Jointed appendages (III) presence of chitinous exoskeleton/exoskeleton made of chitin (IV) Bilateral symmetry.
|Wings present||Wings are absent|
|Proboscis present||Mandibles are present|
|Proleg absent||Mandibles are present|
|Legs are longer||Legs are shorter|
|Claspers are absent||Claspers are present|
|Has one pair of compound eyes||Has simple eyes|
|Has antennae||Absence of antennae|
|Osmeterium absent||Osmeterium present|
|Presence of proboscis||Presence of mandibles|
|Clubbed/rounded/knobbed antennae||Not clubbed/rounded/knobbed antennae/tapering antennae|
|Wing is membreneous/soft||Harder/less membraneous wings/forewings are leathery|
|Surface of wing is powdery/have scales/eye spots||Surface of wing is not powdery/absence of scales/eye spots|
|Hind limbs/legs smaller/shorter/less muscular||Hind limbs/legs/larger and elongated/more muscular|
|Abdomen is hairy||Abdomen is not hairy/smooth|
(c) Relationship between specimens C/Butterfly and D/Caterpillar:
(i) C/butterfly is the adult/image of D/Caterpillar
(ii) D/Caterpillar is the larva/larva stage of C/Butterfly
(d) (i) Habitat of specimen D/Caterpillar: Garden/Citrus leaves/vegetables/leaves/fruits/green plant has three pairs of true legs with claws for locomotion. (III) it has claspers for attachment to vegetation/twid (IV) presence of four pairs of prologs/false legs: for climbing (V) its coloured pattern enables it to blend with its environment/camouflages/escape predators (VI) it has spiracles for gaseous exchange, (VII) it has simple eyes for vision (VIII) has osmeterium as defense mechanism/which emits foul smell to scare away predators.
(e) Diagram/drawing of dorsal view of specimen C/Butterfly
2(a)observable features of biological importance in
Specimen F/Carrot: (i) Main root/tap root/swollen/root tuber (ii) Presence of lateral roots (iii) Presence of short stem (green) (iv) Presence of foliage leaves (v) Part of main root tapering
Specimen G/Irish potato: (i) Swollen stem/stem tuber (ii) Bud(s)/ eye (iii) Lenticels (iv) scale leaf (v) adventitious roots(s)
(b) (i) Classification of (I) Specimen F/Carrot: Root tuber (II) Specimen G/Irish Potato: Stem tuber. Stem (above the swollen tap root). Specimen G/Irish Potato: Swollen, Stem/tuber presence of bud(s)/eye presence of scale leaves/leaf presence of lentice(s).
(c) Class of specimen H and J: insect
(d) (i) Observable differences between specimen H and J.
|H/Adult mosquito||J/Adult cockroach|
|Smaller in size||Big/large in size|
|A pair of wings||Two pairs of wings|
|Absence of hard hind wing||Presence of hard hind wing/elytra|
|Shorter antennae||Longer antennae|
|Absence of maxillary palp/maxilla||Presence of maxillary palp/maxilla|
|Thin legs||Thick/large legs|
|Absence of spines on legs||Presence of spine on legs.|
(ii) Similarities between specimens H/adult mosquito and J/adult cockroach:
(i) Presence of a pair of compound eyes
(II) Body is divided into three divisions/head, thorax and abdomen
(iii) three pairs of/six(walking) legs
(IV) presence of jointed appendages
(V) presence of a pair of membraneous wings
(VI) Presence of a pair of antenna
(VII) Both have exoskeleton made of chitin
(VIII) Segmented Body.
(i) Feeding Habit of Specimen H/adult mosquito: Piercing and sucking. Specimen J/adult cockroach: Biting and chewing
(ii) Observing features used for feeding in specimen J/adult cockroach: Mandible maxillae labrum
4. (a) (i) Phylum of Specimen R/Earthworm: Annelida
(ii) Reasons for the classification of Specimen R/Earthworm:
(I) Presence of metameric segmentation/segments are separated from each other (by septa
(II) They are bilaterally symmetrical
(II) Segments are separated from each other
(IV) Presence of chaetae
(V) Body is covered by thin collagen cuticle
(VI) body is long and cylindrical.
(iii) Habitat of Specimen R/Earthworm:
(I) Under decaying leaves
(II) Wet/moist soil
(III) In open savanna/savannah beneath tall grasses
(IV) In the forests in decaying tree-stumps.
(b) (i) Features of adaption of Specimen R/Earthworm:
(I) Bristle like Caetae/seatea for locomotion
(II) Mosit skin for gaseous exchange
(III) Pointed anterior for burrowing into the soil
(IV) Slimy body reduces friction during movements
(V) Citellum for attachment during exchange of sperms/reproduction/secretes cocoon (in which it eggs are deposited).
(ii) Economic importance of Specimen R/Earthworm:
(I) it aerates the soil
(II) it enriches/improves soil fertility
(III) its secretions neutralize the acid soil
(IV) Used as bait for fishing
(V) As food for some birds.
(c) Diagram/Drawing of the dorsal view of Specimen R/Earthworm
(d) Type of fruit: Specimen S/unripe mango fruit – Drupe, Specimen T/tomato fruit – Berry.
(e) (i) Observable differences between Specimens S and T
|Specimen C/Unripe Mango Fruit||Specimen T/tomato Fruit|
|Green in colour||Red/Yellow in colour|
|One seeded||Many seeded|
|Stony/hard endocarp||Fleshy/Succulent/Soft endocarp|
|Fibrous mesocarp||Succulent mesocarp|
|Seed large||Seed(s) small|
|Basal placentation||Axile placentation|
|Mesocarp and endocarp are fused||Mesocarp had endocarp are not fused|
(ii) Similarities between specimens S and T:
(III) Both have three layers/epicarp/mesocarp/endocarp/pericarp/fruit wall
(IV) Coloured epicarp/pericarp
(VI) Both have thin epicarp
(VII) both have fleshy mesocarp.
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taproot, main root of a primary root system, growing vertically downward. Most dicotyledonous plants (see cotyledon), such as dandelions, produce taproots, and some, such as the edible roots of carrots and beets, are specialized for food storage.
Upon germination, the first structure to emerge from most seeds is the root from the embryonic radicle. This primary root is a taproot. In plants in which the taproot persists, smaller lateral roots (secondary roots) commonly arise from the taproot and may in turn produce even smaller lateral roots (tertiary roots). This serves to increase the surface area for water and mineral absorption. In other plants, the initial taproot is quickly modified into a fibrous, or diffuse, system, in which the initial secondary roots soon equal or exceed the primary root in size and there is no well-defined single taproot. Fibrous root systems are generally shallower than taproot systems.
What Is the Difference Between Taproots and Fibrous Roots?
A taproot is a large main root that comes off of the stem and has many smaller lateral roots a fibrous root system has many roots of the same size that break off into small lateral roots. Dandelions, poison ivy and carrots are all examples of taproots sweet potatoes are the fleshy part of a fibrous root.
The taproot system allows plants to anchor better, get sources of minerals and water from further into the ground than fibrous rooted plants. The fibrous system is more susceptible to drought however, it also allows the plant to respond faster to an application of fertilizer.
Dicots and monocots are the two classes of flowering plants. The majority of taproot systems are composed of dicots and conifers. The taproot is the main root in the plant, but there are smaller roots that grow out from the root. A tap root grows downward into the ground. For this reason, carrots are only picked out of the ground. Taproots are able to dig deep into the ground to reach reserves of water to keep themselves sustained.
Monocots, including onions and grasses, are fibrous root systems. The roots of these plants are somewhat small but are generally around the same size and grow out of the stem. From the main roots, smaller lateral pieces of roots grow outward and begin to plant themselves in to the ground. The smaller lateral roots are able to attach and cling to the soil, which makes them ideal for the prevention of erosion.