1. What are the main types of cells in the ground tissue system?
There are three major types: parenchyma, collenchyma, and sclerenchyma.
2. What is the main role of parenchyma cells?
Parenchyma cells can perform diverse functions, namely storage, photosynthesis, and repairing of tissues.
3. How do the collenchyma cells contribute to plant growth?
Collenchyma cells have a primary function of flexible support for growing young stems and leaves and thus help in growth and movement.
4. What function do sclerenchyma cells have in plants?
Sclerenchyma cells provide rigid support to mature plant organs and, thus, contribute to the general mechanical strength of the plant.
5. How does the ground tissue system help to transport nutrients?
Ground tissue cells transmit nutrients between vascular tissues and other parts of the plant and, in doing so, support general plant health.
6. What is the role of mucilage cells in the ground tissue system?
Mucilage cells are specialized cells in the ground tissue that produce and store mucilage, a slimy secretion. This mucilage can serve various functions, including water retention in desert plants, seed dispersal, and protection against pathogens and herbivores.
7. How does the ground tissue system adapt in plants living in low-light environments?
In shade-adapted plants, the ground tissue in leaves often shows modifications such as a reduced palisade layer and an increased proportion of spongy mesophyll. This adaptation maximizes light capture by increasing internal light scattering within the leaf.
8. What is the function of pith in the ground tissue system?
Pith, located in the center of stems and sometimes roots, primarily provides structural support through turgor pressure in its parenchyma cells. It can also serve as a storage tissue for water and nutrients, and in some plants, it may break down to form hollow stems.
9. What is the role of tannin cells in the ground tissue system?
Tannin cells are specialized cells in the ground tissue that produce and store tannins, which are astringent chemical compounds. These compounds play a role in plant defense against herbivores and pathogens, and contribute to the taste of many fruits and vegetables.
10. What is the function of bundle sheath cells in the ground tissue system?
Bundle sheath cells are specialized parenchyma cells that surround vascular bundles. In C4 plants, they play a crucial role in photosynthesis by concentrating CO2 around RuBisCO. In other plants, they help regulate the movement of substances between the vascular tissue and surrounding cells.
11. How does the ground tissue system differ in monocots and dicots?
In monocots, the ground tissue is typically not differentiated into distinct regions. In dicots, the ground tissue is often divided into three regions: the cortex (outer layer), pith (central region), and pith rays (connecting cortex and pith through vascular tissue).
12. What is the difference between cortex and pith in the ground tissue system?
The cortex is the outer region of the ground tissue in stems and roots, located between the epidermis and vascular tissue. The pith is the central region of ground tissue, typically found in stems and sometimes in roots. The cortex is generally involved in storage and photosynthesis, while the pith mainly provides support and storage.
13. What is the relationship between the ground tissue system and vascular bundles?
The ground tissue system surrounds and separates vascular bundles. In dicot stems, ground tissue forms pith rays that extend between vascular bundles, connecting the pith to the cortex and facilitating lateral transport of substances.
14. How does the ground tissue system contribute to the formation of lateral roots?
Lateral roots originate from the pericycle, which is the outermost layer of the vascular cylinder. However, the endodermis and cortex (both part of the ground tissue system) play a crucial role by undergoing programmed cell death to allow the emerging lateral root to pass through.
15. How does the ground tissue system adapt in plants living in aquatic environments?
Aquatic plants often develop extensive aerenchyma tissue within their ground tissue system. This tissue creates large air spaces that provide buoyancy and allow for efficient gas exchange in the oxygen-poor underwater environment.
16. What role does the ground tissue system play in wound healing in plants?
When a plant is wounded, parenchyma cells in the ground tissue near the wound site can dedifferentiate and divide to form callus tissue. This callus helps to seal the wound and can potentially regenerate new tissues.
17. How does the ground tissue system adapt in succulent plants?
In succulent plants, the ground tissue system is modified to store large amounts of water. The parenchyma cells in leaves or stems become enlarged and have thin, flexible cell walls that can expand as they fill with water, allowing the plant to survive in arid conditions.
18. How does the ground tissue system contribute to leaf structure and function?
In leaves, the ground tissue system forms the mesophyll, which is divided into palisade and spongy layers. The palisade layer contains tightly packed chlorenchyma cells for efficient photosynthesis, while the spongy layer has loosely arranged cells with large air spaces for gas exchange.
19. How does the ground tissue system contribute to plant movement?
Specialized parenchyma cells in the ground tissue can facilitate plant movements through changes in turgor pressure. Examples include the pulvinus in legume leaves for nyctinastic movements and the cells responsible for the closing of Venus flytrap leaves.
20. How does the ground tissue system contribute to the ripening of fruits?
During fruit ripening, parenchyma cells in the ground tissue undergo changes in cell wall composition and turgor pressure. Enzymes break down cell wall components, softening the fruit. Additionally, these cells often accumulate sugars and pigments, changing the fruit's flavor and color.
21. How does the ground tissue system contribute to photosynthesis?
The ground tissue system, particularly in leaves, contains chlorenchyma (parenchyma cells with chloroplasts) that carry out photosynthesis. These cells are typically located in the mesophyll, which is part of the ground tissue system.
22. What role does the ground tissue system play in storage?
The ground tissue system often contains specialized storage parenchyma cells that can accumulate and store various substances such as starch, proteins, and lipids. Examples include the flesh of fruits and the internal tissues of tubers.
23. What is aerenchyma and how does it relate to the ground tissue system?
Aerenchyma is a specialized type of parenchyma tissue with large air spaces. It's part of the ground tissue system and is commonly found in aquatic plants. Aerenchyma helps with buoyancy and allows for efficient gas exchange in waterlogged environments.
24. What is the role of idioblasts in the ground tissue system?
Idioblasts are specialized cells within the ground tissue that differ in structure and function from surrounding cells. They can contain crystals, oil, or other substances and may play roles in defense, storage, or structural support.
25. How does the ground tissue system facilitate gas exchange in plants?
The ground tissue system contains intercellular spaces, particularly in leaves and stems, that form a continuous network called the intercellular air space system. This system allows for the diffusion of gases (CO2 and O2) throughout the plant, facilitating photosynthesis and respiration.
26. What is the function of collenchyma in the ground tissue system?
Collenchyma cells provide mechanical support to growing parts of the plant. They have unevenly thickened cell walls that remain flexible, allowing for continued growth while still offering support to young stems, petioles, and leaf veins.
27. How does the ground tissue system contribute to the formation of tendrils?
Tendrils are modified stems or leaves used for climbing. The ground tissue in tendrils often shows adaptations such as increased collenchyma for flexibility and touch-sensitive cells that trigger coiling responses when the tendril contacts a support.
28. How does the ground tissue system contribute to the formation of galls?
Galls are abnormal plant growths usually induced by other organisms. When galls form, cells in the ground tissue often undergo rapid division and expansion. These modified ground tissue cells may develop specialized functions to support the gall-inducing organism or to isolate it from the rest of the plant.
29. How does the ground tissue system provide structural support to plants?
Collenchyma and sclerenchyma cells within the ground tissue system provide mechanical support to plants. Collenchyma cells have thickened cell walls that offer flexibility, while sclerenchyma cells have lignified walls that provide rigidity.
30. What is the difference between living and non-living cells in the ground tissue system?
The ground tissue system contains both living and non-living cells. Parenchyma and collenchyma cells are typically living at maturity and can perform various metabolic functions. In contrast, mature sclerenchyma cells are usually dead, serving primarily as structural support.
31. What is the role of stone cells in the ground tissue system?
Stone cells, or sclereids, are a type of sclerenchyma cell found in the ground tissue. They have extremely thick, lignified cell walls and often occur in groups, providing mechanical strength and protection. They contribute to the gritty texture in pears and the hard shells of nuts.
32. How does the ground tissue system contribute to plant defense mechanisms?
Cells in the ground tissue system can produce and store various defensive compounds, such as tannins, alkaloids, and latex. Additionally, some plants develop sclerenchyma cells with thick, lignified walls as a physical barrier against herbivores and pathogens.
33. How does the ground tissue system contribute to the formation of thorns?
Thorns are modified stems that develop from axillary or terminal buds. The ground tissue system in thorns is typically composed of densely packed sclerenchyma cells, providing the hardness and sharpness characteristic of these structures.
34. What are the primary cell types found in the ground tissue system?
The main cell types in the ground tissue system are parenchyma, collenchyma, and sclerenchyma. Parenchyma cells are the most common and least specialized, while collenchyma and sclerenchyma provide structural support.
35. What is the function of resin ducts in the ground tissue system of conifers?
Resin ducts are specialized intercellular spaces lined with secretory cells, found in the ground tissue of many conifers. They produce and store resin, a sticky substance that helps protect the tree against insect attacks and fungal infections.
36. What is the role of transfer cells in the ground tissue system?
Transfer cells are specialized parenchyma cells with ingrowths in their cell walls, increasing the surface area for transport. In the ground tissue, they often occur near vascular tissues and facilitate the efficient transfer of solutes between different plant tissues.
37. What is the function of crystal-containing cells in the ground tissue system?
Some cells in the ground tissue system contain crystals, often of calcium oxalate. These crystals may serve several functions, including calcium regulation, protection against herbivores due to their sharp edges, and possibly as a means of sequestering excess oxalic acid.
38. What is the role of endodermis in the ground tissue system of roots?
The endodermis is the innermost layer of the cortex in roots and is part of the ground tissue system. It forms a selective barrier controlling the movement of water and solutes between the cortex and the vascular cylinder, primarily due to the Casparian strip in its cell walls.
39. What is the ground tissue system in plants?
The ground tissue system is one of the three main tissue systems in plants, alongside the dermal and vascular systems. It comprises all tissues that are neither dermal nor vascular, filling the space between these systems and performing various functions such as photosynthesis, storage, and support.
40. What is the role of the mesocarp in fruits, and how does it relate to the ground tissue system?
The mesocarp is the middle layer of the fruit wall and is derived from the ground tissue of the ovary. It often becomes fleshy and may store water, sugars, and other nutrients. The cells of the mesocarp can undergo significant modifications during fruit development, contributing to the fruit's texture, flavor, and nutritional content.
41. What is the role of the hypodermis in the ground tissue system?
The hypodermis is a layer of ground tissue just beneath the epidermis in some plants. It can provide additional protection, support, and sometimes participates in photosynthesis. In roots, it may develop into an exodermis with Casparian strips, regulating water and solute movement.
42. How does the ground tissue system adapt in plants with parasitic lifestyles?
In parasitic plants, the ground tissue system often shows modifications to support the parasitic lifestyle. For example, in plants like dodder (Cuscuta), specialized structures called haustoria develop from the ground tissue to penetrate the host plant and absorb nutrients.
43. How does the ground tissue system adapt in plants living in high-salinity environments?
In halophytes (salt-tolerant plants), cells in the ground tissue system often have specialized vacuoles that can sequester excess salt. Some plants also develop succulent characteristics in their ground tissue to store more water, helping to dilute salt concentrations.
44. How does the ground tissue system contribute to the formation of tubers?
Tubers, such as potatoes, form when portions of underground stems (rhizomes or stolons) swell due to the accumulation of starch in the ground tissue. The parenchyma cells in the pith and cortex enlarge and fill with starch grains, creating a storage organ.
45. How does the ground tissue system adapt in plants with crassulacean acid metabolism (CAM)?
In CAM plants, the ground tissue system, particularly in leaves and stems, contains large vacuoles that can store organic acids produced during nighttime CO2 fixation. The cells also have a high density of chloroplasts to efficiently use the stored CO2 for photosynthesis during the day.
46. How does the ground tissue system contribute to the formation of pneumatophores?
Pneumatophores are specialized roots that grow upwards in some mangrove species. The ground tissue in pneumatophores contains extensive aerenchyma, allowing for gas exchange in oxygen-poor, waterlogged soils. The cortex also often contains specialized cells for gas exchange.
47. How does the ground tissue system adapt in plants living in nutrient-poor environments?
In nutrient-poor environments, the ground tissue may develop specialized structures for nutrient acquisition. For example, in carnivorous plants, parts of the ground tissue may form digestive glands to absorb nutrients from trapped insects.
48. How does the ground tissue system contribute to the formation of nectaries?
Nectaries are specialized structures that produce nectar to attract pollinators. They often develop from modified ground tissue, particularly parenchyma cells, which become specialized for sugar production and secretion.
49. What is the function of silica cells in the ground tissue system of grasses?
Silica cells are specialized cells in the ground tissue of grasses that accumulate silica. These cells contribute to the structural support of the plant and may also play a role in defense against herbivores and pathogens by making the tissue more abrasive and less digestible.
50. How does the ground tissue system adapt in plants with symbiotic nitrogen-fixing bacteria?
In legumes, specialized structures called nodules develop on the roots to house nitrogen-fixing bacteria. The ground tissue in these nodules is modified to support the symbiotic relationship, with cells enlarging to accommodate the bacteria and developing specialized functions for nutrient exchange.
51. What is the role of secretory cavities in the ground tissue system?
Secretory cavities are specialized structures within the ground tissue that produce and store various substances such as essential oils, resins, or mucilage. They play roles in plant defense, attraction of pollinators, and other ecological interactions.
52. What is the function of bulliform cells in the ground tissue system of grass leaves?
Bulliform cells are large, thin-walled cells found in the upper epidermis and adjacent ground tissue of grass leaves. They play a role in leaf rolling during water stress by changing their turgor pressure, which helps reduce water loss through transpiration.
53. How does the ground tissue system adapt in plants with mycorrhizal associations?
In plants with mycorrhizal associations, the cortex of roots (part of the ground tissue system) often develops specialized structures to accommodate fungal hyphae. These may include intracellular structures in endomycorrhizae or a Hartig net in ectomycorrhizae, facilitating nutrient exchange between the plant and fungus.
54. What is the function of motor cells in the ground tissue system of some plants?
Motor cells, also known as bulliform cells in grasses, are specialized large, thin-walled cells in the ground tissue of leaves. They can rapidly change their turgor pressure, causing leaves to fold or roll in response to water stress, thereby reducing water loss through transpiration.
55. How does the ground tissue system contribute to the formation of prop roots in plants like corn or mangroves?
Prop roots, also known as aerial roots, develop from the stem and grow downwards into the soil. The ground tissue in these roots often contains extensive aerenchyma to facilitate gas exchange. In mangroves, the cortex may also develop specialized structures for salt exclusion or secretion.
