Why a potato tuber should be considered an escape
Potatoes belong to the nightshade family:
- in a flower it has 5 fused sepals, 5 fused petals, 5 stamens, 1 pistil.
- all parts of the plant contain the poisonous substance solanine.
Potato fruits are poisonous berries. Potato tubers are modified shoots. Evidence:
- on the tubers there are remains of leaves (brows) and axillary buds (eyes);
- in the light, the tubers turn green, because. leukoplasts turn into chloroplasts (after that, the content of solanine in the tubers increases sharply and they become poisonous).
Tubers grow on modified underground shoots (stolons) extending from the stem. When hilling, the lower part of the potato stem is covered with earth, because of this, the number of stolons, as well as adventitious roots, increases. In addition, when hilling, weeds are destroyed and the soil is loosened (more air enters the roots).
Most of the dry matter of the potato tuber is starch. After long-term storage of tubers, their mass decreases, because starch is gradually converted into glucose, glucose is oxidized, the energy necessary for the life of the tuber is obtained, as well as water and carbon dioxide, which evaporate.
After cooking, potatoes become crumbly because the pectin-like substances that connect the cells are destroyed.
148-1. Potato tubers are formed on
A) lateral roots
B) adventitious roots
C) modified underground shoots - stolons
D) modified underground shoots - rhizomes
148-2. What is the name of the angiosperm organ shown in the photograph?
A) rhizome
B) bulb
B) tuber
D) root
148-3. Potato seeds are produced by
A) root development
B) fertilization
B) tuber formation
D) vegetative propagation
Question 3. How does a potato tuber develop?
From the leaves of the potato through the stems into the underground shoots (stolons), organic substances constantly flow and are deposited in the form of starch in the tops of the stolons. The tops of stolons grow, thicken and turn into large tubers by autumn.
Question 4. Why should a potato tuber be considered an escape?
Question 5. What is the structure of the bulb?
In the lower part of the bulb, for example, onions, there is an almost flat stem - the bottom. Adventitious roots and modified leaves (scales) depart from the bottom. Outer leaves - scales - dry and leathery, they perform a protective function; internal - fleshy and juicy, nutrients are deposited in them. In the axils of the scales there are axillary buds.
Why potatoes are a modified shoot
Home » Potatoes » Why potatoes are a modified shoot
How to prove that a tuber is a modified shoot
A shoot is a stem with leaves and buds. The stem is its axial part, the leaves are its lateral part. The latter develop at nodes, the areas between which are called internodes.
Instruction
- The stem creates the frame of the plant, brings the leaves to the light and conducts water, mineral and organic substances. It can store nutrients. On the stem, not only leaves develop, but also flowers, as well as fruits with seeds. The main functions of leaves are photosynthesis, water evaporation and gas exchange with the environment.
- Modified shoots perform additional functions in the life of the plant. A number of perennial herbaceous plants have peculiar pantries underground. They are modified underground shoots - rhizomes, bulbs, tubers. Above-ground parts die off annually by autumn.
- In rhizomes, bulbs and tubers, reserve nutrients are deposited for the winter. The rhizome is present in nettle, lily of the valley, iris, couch grass, aspidistra. Outwardly, it looks like a root, but it has apical and axillary buds, and membranous scales play the role of modified leaves. Adventitious roots grow from the rhizome, and the apical and axillary buds give rise to young above-ground shoots. In this case, the plant uses the substances stored in the fall.
- With the help of the rhizome, as well as other modified shoots, vegetative propagation of plants can be carried out. By planting a part of the rhizome with a bud and roots into the soil, you can get a new, independent plant organism. Some ornamental plants reproduce by fragmentation of the rhizome.
- Tubers can be observed in potatoes, Jerusalem artichoke (ground pear), corydalis. From the bases of above-ground stems grow underground shoots called stolons. The apical thickenings of the latter are tubers.
- On the upper surface of the tuber, you can see eyes - these are modified buds. The lower side of the tuber is connected to the underground shoot. Like a stem, a tuber can be divided into several characteristic layers: cork, bast, wood, and pith. All these signs prove that the tuber is a modified shoot.
- Nutrients from the leaves flow continuously to the tubers through the stems and stolons. Thus, these tops of underground shoots are saturated with starch and increase in size.
- Bulbs are typical for tulips, lilies, onions, wild goose onions, daffodils. Their lower part is represented by a flattened modified stem - the bottom, on which scales (modified leaves) grow. Outside, the scales are usually leathery and dry, while inside are fleshy and juicy. They store water, sugars and other valuable substances. In the axils of the scales on the bottom are the kidneys. When planted in the ground, a fibrous root system grows from the bulb, and children develop from the kidneys - young bulbs.
Paragraph 10. Modifications of shoots
1. What modifications of the roots do you know? What functions do they perform?
The main functions of the root are the fixation of the plant in the soil, the absorption of solutions of mineral compounds from the soil and their transport to its aerial parts. However, the root can perform some additional functions. At the same time, it acquires certain structural features, called root modifications.
In many plants (for example, beets, carrots), reserve nutrients are deposited in the main root and base of the shoot. As a result of this, the main root thickens and turns into a root crop.
In other plant species (for example, dahlia, spring chistyak, sweet potato), reserve nutrients are deposited in additional or lateral roots, which acquire a tuberous shape. Such modifications are called root tubers.
In some plants growing in swamps and waterlogged soils, respiratory roots are formed. These are lateral roots growing upward and rising above the surface of the soil (or water). In waterlogged soils, due to the low oxygen content, the respiration of the underground part of the plant becomes more difficult. Therefore, such modified roots absorb oxygen directly from moist air.
There are also trailing roots. These are short additional roots growing along the aerial part of the stem. With their help, climbing stems of plants cling to a support. Remember ivy, which can attach itself even to the smooth vertical walls of houses.
There are also supporting roots that act as props.
A special type of root modification is observed in orchids. Some species of these plants are able to settle on tree trunks of tropical rainforests. Their aerial roots hang freely and allow them to draw water from moist air.
2. What modifications of leaves do you know? What is their function?
Leaf modifications - irreversible changes in the shape of leaves developed during evolution as a result of the adaptation of plant organs to environmental conditions (i.e., with the performance of new functions by leaves).
1. Thorns - one of the most common modifications; they serve as protection against being eaten by animals (cacti, euphorbia, barberry, white locust, camel thorn).
2. Antennae (in complex leaves of some plant species) cling to a support, carrying the entire shoot to the light (peas, vetch).
3. The storage function is performed by juicy scales of bulbs (onion, garlic), aloe leaves, cabbage.
4. The covering scales of the buds protect the delicate rudimentary leaves and the growth cone from adverse environmental conditions.
5. Trapping devices ensure the life of insectivorous plants in swamps in conditions of a lack of nitrogen and other elements of mineral nutrition. The leaves of such plants have changed beyond recognition, turning into traps (Venus flytrap), jugs (nepentes). The leaves of some plants with their shiny, brightly colored droplets on the hairs attract ants, flies, mosquitoes, and other small insects; the juice released at the same time contains digestive enzymes (dew).
3. What are the main functions of the stem?
The stems perform two main functions:
The stems carry the leaves to the light (support function);
The stem transports substances between leaves and roots.
4. What is called an escape?
A stem with leaves and buds on it is called a shoot.
Laboratory work
1. Consider a potato tuber. Find the base and top.
2. Examine the eyes. What is their location on the tuber? Examine the kidneys in the eye using a magnifying glass.
On the surface of the tuber in the recesses there are 2-3 buds, called eyes. There are more eyes on that side of the tuber, which is called the top. The opposite side - the base - the tuber is connected to the stolon.
3. Make a thin cross section of the tuber. Examine it to the light. Compare the cross section of the tuber with the cross section of the stem (Fig. 42).
4. Draw a cross section of the tuber.
See the answer to question #3.
5. Drop iodine on the tuber cut. Explain what happened.
If you drop iodine on a tuber cut, it will turn blue-violet, because. starch, when interacting with iodine, gives such a reaction. In potatoes, starch is contained in large quantities (this is the main storage substance of potato tubers).
6. Prove that a tuber is a modified underground shoot.
The cross section of the tuber is similar in structure to the cross section of the stem. When considering, cork, bast, wood and core can be distinguished.
Laboratory work
Consider the external structure of the bulb. What is the importance of dry scales?
The outer scales are dry and leathery - they perform a protective function.
2. Cut the onion lengthwise. Draw a longitudinal section of the bulb, mark the scales, bottom, buds, adventitious roots.
3. Prove that the bulb is a modified underground shoot.
Like the ground shoot, the stem has apical and axillary buds and leaves.
1. What modified underground shoots do you know? Name plants that have a rhizome, tuber, bulb.
Modified underground shoots - rhizomes, tubers and bulbs.
Many plants have a rhizome, for example, nettle, wheatgrass, iris, lily of the valley, aspidistra houseplant.
Tubers are found, for example, in potatoes, Corydalis, Jerusalem artichoke fodder plant (ground pear).
Bulbs form perennial plants - onion, lily, tulip, narcissus, wild goose onion.
2. How does a potato tuber develop?
Underground shoots, on which tubers develop, grow from the bases of above-ground stems. These shoots are called stolons. Tubers are apical thickenings of stolons.
Like the ground shoot, there are apical and axillary buds, from which young above-ground shoots develop in spring.
The cross section of the tuber is similar in structure to the cross section of the stem. When considering, cork, bast, wood and core can be distinguished.
4. What is the structure of the bulb?
In the lower part of the onion bulb there is an almost flat stem - the bottom. On the bottom there are modified leaves - scales. The outer scales are dry and leathery, while the inner scales are fleshy and juicy. On the bottom there are kidneys located in the axils of the scales.
5. How to prove that the rhizome and bulb are modified shoots?
As with the ground shoot on the rhizome and bulb, there are apical and axillary buds, as well as modified leaves (membrane scales on the rhizome, juicy and dry scales on the bulb). Adventitious roots grow from the rhizome and bottom (stem in the bulb), and young above-ground shoots develop from the apical or axillary bud in spring.
6. What above-ground modifications of the escape do you know?
Above-ground modifications of the shoot are the thorns of a wild apple tree, pear, hawthorn, which protect plants from being eaten by animals. The tendrils of grapes, cucumbers, pumpkins, melons, mustaches of strawberries are also modified shoots. Another example of an elevated modified shoot is the thickening of the internodes of the kohlrabi stem.
By what signs can tubers be distinguished from a root crop, a rhizome from a root?
The tuber and rhizome will have buds, as well as modified leaves.
1. Place an onion bulb in a jar with a narrow neck so that it does not fall through, but only touches the bottom of the water poured into the jar. Watch the bulb develop adventitious roots and green leaves. Why does it grow even though it is not in the soil?
The bulb is an accumulation of useful substances necessary for leaves and roots. In the presence of heat and moisture, growth begins. That is, the bulb provides the plant with everything it needs even without soil.
2. With the onset of warm spring weather, watch the flowering of bulbous and rhizomatous plants. Name these plants. Mark the beginning and end of flowering, and also indicate what is typical for these plants in this period of the year.
1. Simple early tulips bloom in early May for 15–30 days. The change of generations of bulbs, unlike daffodils, occurs annually. During a short spring growing season, the tulip blooms, bears fruit and lays young bulbs underground, and the faded bulb dies.
2. Daffodils bloom in April-May. Narcissus has a perennial bulb. After the end of flowering, the leaves of faded daffodils are not cut off, but they are waiting for them to dry. During this period, the storage of nutrients in the bulbs occurs.
1. Lilies of the valley bloom from mid to late May. After the end of the flowering period, lily of the valley fruits appear - small red berries.
2. Irises bloom profusely from late May to mid-July. In the summer, a flower bud is laid at the irises, so that irises with already formed buds overwinter, from which new flowers will appear in the new season.
why is the potato a modified shoot?
Igor Kulikov
Rather, a potato tuber is a modified shoot. The tuber has all the features inherent in an ordinary shoot - it is a thickened and shortened stem of a herbaceous plant, it has buds. The structure of tissues is really modified in connection with the functions performed. But there are integumentary tissues, conductive bundles, mechanical and storage tissues. Moreover, the parenchyma is the most developed. In stolons (this is also an escape), on the contrary, vascular bundles and mechanical tissues are most developed.
why a potato tuber is a modified underground shoot. really need help please.
Kitten Woof!
A potato tuber is a modified shoot, because the tuber has apical and lateral buds (as on a regular shoot) - eyes. The area of the tuber between the buds (eyes) is the internode. At the base of each kidney there is a brow - the place of attachment of the reduced leaf. As on ordinary shoots, the buds on the tubers are spirally arranged. Above-ground leafy and flowering shoots develop from the tuber eyes. Therefore, in addition to the storage function, tubers perform the function of vegetative propagation.
Jimmy Kane
has all shoot structures: stem, leaf, buds
how to prove that a tuber is a modified underground shoot?
Zinaida Zhenchevskaya
The potato tuber is a modified shoot because
on the tuber there are apical and lateral buds (as on a regular shoot) - eyes.
The area of the tuber between the buds (eyes) is the internode.
At the base of each kidney there is a brow - the place of attachment of the reduced leaf.
As on ordinary shoots, the buds on the tubers are spirally arranged. Above-ground leafy and flowering shoots develop from the tuber eyes.
Therefore, in addition to the storage function, tubers perform the function of vegetative propagation.
Hammer of the Scots
Like the stem, the tuber has a storage function
It has buds, and in cross section it shows the same zones as on the shoot.
Prove that a potato tuber is a modified underground shoot?
Peculiar underground pantries have perennial herbaceous plants. The above-ground parts of these plants die off annually by autumn. Roots and modified underground shoots remain in the soil. They don't look like regular overhead ones. It is in these modified shoots that reserves of organic matter are deposited for the winter. Modified shoots are rhizomes, tubers and bulbs.
If you dig the rhizome of any plant out of the ground, you can see that outwardly it resembles a root. But the rhizome, like the above-ground shoots, has apical and axillary buds, as well as membranous scales - modified leaves. Adventitious roots grow from the rhizome.
From the apical or axillary buds of the rhizome, young above-ground shoots develop in spring. At the same time, they use the nutrients deposited in the rhizome in autumn. If a piece of rhizome with a bud and adventitious roots is planted in the soil, a new, independently living plant will develop.
Tubers are characteristic of few plants. Underground shoots, on the tops of which tubers develop, grow from the bases of above-ground stems; these shoots are called stolons. Tubers are apical thickenings of stolons.
The tuber has short internodes; it does not contain chlorophyll, but when exposed to light, it can turn green. Consider a potato tuber. On its surface, in depressions of 2-3, there are buds, or eyes. There are more eyes on that part of the tuber, which is called the top. The opposite side - the base - the tuber is connected to the stolon. The structure of the tuber convinces us that the tuber is a modified underground shoot.
Organic substances constantly flow from the leaves of the potato through the stems into the stolons and are deposited in the tops in the form of starch. The tops of stolons grow, thicken and turn into large tubers by autumn.
sergey mmmm
why a potato tuber and an onion bulb are modified shoots
Because they are formed from the underground part of the shoot, and shoots are called that part of the plant that has interlesions and nodes, and in most cases they do not suck in water.
How to prove that a potato tuber is an escape?
Elena Kazakova
1) it has eyes (kidneys). including the apex
2) the internal structure of the tuber is similar to the structure of the stem
Conclusion: a tuber is a modified underground shoot that serves to store nutrients (starch)
Andrey Ivanov
Galya Blue-eyed
escape from what or from what?
Potato tubers are interesting formations. In the context, they have the same structure as the stem-bark, bast, wood, core. the core (the central region of the stem tissue) makes up a significant part of the tuber.
The sprouts on the tuber, as well as the sprouts on the stem, are arranged in one or two spirals. Between the eyes-buds are internodes. There is an apical bud from which the main shoot develops.
Thus, the external and internal structure of the tuber indicates that it is a modified underground shoot.
1. The root absorbs minerals and water from the ground. Does the potato do it?
2. Kidneys grow from potatoes, like a shoot.
3. As in an escape, nutrients are stored in the potato.
