Biology

Plant Transport and Physiology

1,834 Questions

Access a comprehensive set of questions on plant transport mechanisms and physiological adaptations. Topics include water movement, translocation of food, and plant responses to external stimuli. These biology questions are essential for medical entrance exams and other science competitive tests.

Xylem and phloem transportTranspiration and evaporationPlant adaptationsGeotropic and phototropic responsesWater absorption by rootsRespiration in roots

Plant Transport and Physiology Questions

Multiple choice botany ecological adaptations, succession and ecological services extreme adaptations adapting to a habit adaptive features aquatic plant adaptations pollination through water

Xerophytes have very small leaves or spines to.

  1. Reduce weight

  2. Reduce loss of water

  3. Reduce volume

  4. Be beautiful
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Xerophytes have very small leaves or spines to reduce loss of water.

A xerophyte is a species of plant that has adapted to survive in an environment with little liquid water, such as a desert or an ice- or snow-covered region.

Morphologically and physiologically the xerophytes are adapted to conserve water and also to store large quantities of water in the dry periods. Some species are adapted to survive long periods of dehydration in their tissues. During the periods of dehydration the metabolic activity of them may be shut down.

Morphological Adaptations in xerophytic plants

Almost all the xerophytic plants have similar shapes, structure and forms and they look very similar though these plants are not genetically related. This process of evolution is known as convergent evolution.

Reduction of Surface Area
  • Xerophytic plants usually have less surface area than other plants, this reduces the area that is exposed to the air and helps in reducing water loss by evaporation process.
  • These plants have smaller leaves and few branches than other plants.
Reduction in Air Flow
  • Some xerophytes plants have tiny hairs on their surface; this provides a wind break and reduces air flow, which reduces the rate of evaporation.
  • In such environments the region under the leaves/spines is the place of transpiration and this place is more saturated than the normal water vapor.
  • If there is less movement of air, there is reduced potential gradient of the water vapor hence reducing transpiration.
  • Spines trap moisture and also slow the movement of air over the tissues.
Reflectivity
  • The color of these plants or of the waxes or hairs on its surface may help to reflect sunlight and reduce evaporation.
  • Physiological Adaptations of Xeropyhtes
  • Some xerophytic plants store water in structures like roots, trunks, stems and leaves. Water is stored in swollen parts of the plant known as succulence. A swollen trunk part or the root part at the ground level of a plant is called caudex.
  • Stomata are tiny pores on the surface of xerophytic plants; they stay open only at night to reduce evaporation.
  • These plants may secrete resins and waxes on their surface which reduce evaporation.
  • Some plants drop their leaves in the times of dryness or they modify the leaves produced so that they are smaller and less surface area of the plants is exposed.
  • Xerophytic plants may go dormant and stop growing during dry periods; they may also change the kind of photosynthesis or they may change the storage allotment of the products of photosynthesis by growing new leaves to the roots.
  • Seeds also may be modified to require excessive amount of water before the process of germination, so to ensure that there is sufficient supply of water for the survival of the seedling.
  • So, the correct answer is 'Reduce loss of water'
Multiple choice botany ecological adaptations, succession and ecological services extreme adaptations adapting to a habit adaptive features aquatic plant adaptations pollination through water

In xerophytes, the osmotic concentration of cell sap is

  1. Less than normal

  2. Normal

  3. More than normal

  4. No osmotic pressure at all
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The osmotic concentration of cell sap is higher in xerophytes to allow them to absorb water in an otherwise water deficient environment. The higher osmotic concentration would mean a lower water potential. A lower water potential will be advantageous to xerophytes as water always flows from a higher water potential to lower water potential.

Multiple choice botany ecological adaptations, succession and ecological services extreme adaptations adapting to a habit adaptive features aquatic plant adaptations pollination through water

Plants give out water through the pores present under their leaves. The plants living in deserts need to reduce the loss of water because water is very scarce in deserts. Which of the following is an adaptation developed by the desert plants to manage the above situation?

  1. They have lots of branches and leaves.

  2. They do not shed leaves in the summer.

  3. They develop roots which come above the ground.

  4. Their leaves are modified into spines.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Most species of desert plants have lost true leaves, retaining only spines, which are highly modified leaves. As well as defending against herbivores, spines help prevent water loss by reducing air flow close to the cactus and providing some shade. In the absence of leaves, enlarged stems carry out photosynthesis.

So, the correct answer is 'Their leaves are modified into spines'.

Multiple choice botany ecological adaptations, succession and ecological services extreme adaptations adapting to a habit adaptive features aquatic plant adaptations pollination through water

Which is the trait that enabled the plants for the first time to colonise themselves on dry land?

  1. Lignified cell wall

  2. Vascular tissue

  3. Cuticle

  4. Stomata
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The cuticle is a waxy coating over the surface of leaves and plants. It forms a waterproof coating over the surface of leaves and plants. It prevents water loss from plants and also prevents the plants from getting desiccated. It also prevents the intake of gases into the plants. 

So, option C "Cuticle" is the correct answer.

Multiple choice botany ecological adaptations, succession and ecological services extreme adaptations adapting to a habit adaptive features aquatic plant adaptations pollination through water

Phreatophytes are xerophytes with roots

  1. Spread along the soil surface

  2. Well spread in the soil

  3. Very deep reaching ground water fringe

  4. Very deep but well above ground water
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A phreatophyte is a deep-rooted plant that obtains a significant portion of the water that it needs from the phreatic zone (zone of saturation) or the capillary fringe above the phreatic zone. Phreatophytes are plants that are supplied with surface water and often have their roots constantly in touch with moisture. These plants have very deep roots that are able to reach the water table. So the correct answer is ' Very deep reaching ground water fringe'. 

Multiple choice botany ecological adaptations, succession and ecological services extreme adaptations adapting to a habit adaptive features aquatic plant adaptations pollination through water

Drought endurers are

  1. Succulent xerophytes

  2. Perennial xerophytes

  3. Annual xerophytes

  4. Both B and C
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Drought endurers are plants that can survive drought periods by maintaining their physiological functions, typically through deep root systems or water storage, and are usually perennial. Annuals are typically drought escapers.

Multiple choice botany ecological adaptations, succession and ecological services extreme adaptations adapting to a habit adaptive features aquatic plant adaptations pollination through water

In xerophytic leaf, the stomata are situated 

  1. On both surface

  2. On upper surface

  3. On lower surface

  4. Absend from both surfaces
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The xerophytic plants are the plants present in the desert and other dry environments. The rate of transpiration is high in xerophytic plants due to high temperatures. In order to minimize the rate of transpiration, they have sunken stomata.

Thus, the correct answer is option (C),

Multiple choice botany ecological adaptations, succession and ecological services extreme adaptations adapting to a habit adaptive features aquatic plant adaptations pollination through water

Sunken stomata occur in

  1. Xerophytes

  2. Hydrophytes

  3. Mesophytes

  4. Opsanophytes
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sunken stomata are a specific adaptation in xerophytes to create a micro-environment of higher humidity around the pore, thereby reducing the rate of transpiration.

Multiple choice botany ecological adaptations, succession and ecological services extreme adaptations adapting to a habit adaptive features aquatic plant adaptations pollination through water

An adaptation of plants to water scarcity and high temperature is

  1. Succulent stem stores water

  2. Poorly developed root

  3. They shed their leaves

  4. In unfavourable season, plants survive in dormant state as seeds
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Water storage in stem and tubers is an adaptation of plants to thrive in harsh environments with high temperatures and scarce water. Such plants called xerophytes usually develop succulent stems that can store water.
  • They have a very extensive root system to absorb the maximum amount of water from the soil.
  • Other adaptations include thick waxy cuticle, reduced leaf size, densely packed leaves, reduced number of stomata in pitted and grooved positions.
Multiple choice botany ecological adaptations, succession and ecological services extreme adaptations adapting to a habit adaptive features aquatic plant adaptations pollination through water

Opuntia has spine like leaves which help in 

  1. Reducing the rate of transpiration

  2. Increasing the rate of transpiration

  3. Increasing the rate of photosynthesis

  4. Reducing the rate of photosynthesis
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Opuntia has spine which are highly modified leaves. Spines help prevent water loss by reducing the rate of transpiration.
So, the correct option is 'Reducing the rate of transpiration'
Multiple choice botany ecological adaptations, succession and ecological services extreme adaptations adapting to a habit adaptive features aquatic plant adaptations pollination through water

'Pebble plant' have _____________.

  1. Leaves modified to spines

  2. Leaves are absent

  3. Leaves are swollen

  4. Leaves modified to reduce transpiration
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lithops (stone-faced as the plants appear stone-like)  is a genus of succulent plants in the ice plant family, Aizoaceae. They avoid being eaten by blending in with surrounding rocks and are often known as pebble plants or living stones. These are small succulent plants that survive in their harsh environment by having much of the plant body below ground. Each individual plant consists of two succulent leaves fused together in the shape of an inverted cone (although some species will produce multi-headed plants). The fissure at the top of the plant is the division between the two leaves and is spine-like. 

So, the correct answer is 'leaves modified to spines'.

Multiple choice botany ecological adaptations, succession and ecological services extreme adaptations adapting to a habit adaptive features aquatic plant adaptations pollination through water

The most common organic solute stored by xerophytes for maintaining osmotic and water potential is

  1. Glucose

  2. Sucrose

  3. Raffinose

  4. Proline
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Proline is a common compatible solute (osmolyte) accumulated by plants, especially xerophytes and halophytes, to maintain osmotic balance and protect cellular structures under drought stress.

Multiple choice biology adapting to a habit extreme adaptations adaptive features adaptations of organisms

The leaves of desert plants are not torn away by high wind velocity because of

  1. Spines

  2. Bending towards opposite side

  3. Sclerenchymatous tissue that provides extra mechanical support

  4. Tearing of corners while the middle remains saved
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Desert plants often develop sclerenchymatous tissues, which are rigid, dead cells that provide significant mechanical strength and structural support. This reinforcement helps the leaves withstand high wind velocities without tearing.

Multiple choice biology adapting to a habit extreme adaptations adaptive features adaptations of organisms

Sun plants have

  1. More mechanical tissues

  2. Extensive root system

  3. Abundant flowering

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sun plants (heliophytes) are adapted to high-light environments and typically possess more mechanical tissue for structural integrity, extensive root systems to support high transpiration rates, and often show more vigorous growth and flowering compared to shade plants.