biology 2 Flashcards

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1
Q

Swimmerets:

A

Swimmerets are small, leg-like structures found on the abdomen of many aquatic arthropods, particularly crustaceans such as crayfish, crabs, and lobsters.
They are used primarily for swimming and also play a role in reproduction in some species. Male crustaceans often have specialized swimmerets modified for transferring sperm to the female during mating.
Swimmerets are typically arranged in pairs along the underside of the abdomen and are moved rhythmically to propel the animal through the water.

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2
Q

Setae:

A

Setae are small, bristle-like structures found on the body of various invertebrates, including many insects and some annelid worms.
They serve multiple functions depending on the species and location on the body. In insects, setae can be sensory structures used to detect touch, air movement, vibrations, and chemical cues from the environment.
Setae may also function in providing stability and traction during locomotion, such as walking or climbing on surfaces.
In some insects, setae may be specialized for defense, camouflage, or communication.

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3
Q

The characteristics of all living organisms, also known as the properties of life, include the following:

A

Organization: Living organisms exhibit a high level of organization, with complex structures composed of cells, tissues, organs, and organ systems that work together to carry out specific functions.

Metabolism: Living organisms engage in metabolic activities, including the acquisition of nutrients, energy conversion, and the synthesis of molecules necessary for growth, repair, and reproduction.

Homeostasis: Living organisms maintain internal stability and balance through homeostasis, the regulation of internal conditions such as temperature, pH, and water balance, despite changes in the external environment.

Growth and Development: Living organisms undergo growth, which involves an increase in size or number of cells, and development, which involves changes in structure, form, and function as an organism matures.

Reproduction: Living organisms reproduce to perpetuate their species, passing on genetic information to offspring through a variety of reproductive strategies, such as asexual reproduction or sexual reproduction.

Response to Stimuli: Living organisms respond to stimuli from their environment, including physical, chemical, and biological signals, through processes such as movement, behavior, and physiological changes.

Adaptation: Living organisms exhibit adaptations, which are traits or characteristics that enhance their survival and reproductive success in specific environments. Adaptations may arise through natural selection and evolutionary processes.

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4
Q

Parenchyma is a type of simple plant tissue found in various parts of plants, including the leaves, stems, roots, and fruits. It is composed of relatively unspecialized cells that perform a variety of functions essential for plant growth, development, and metabolism.

Characteristics of parenchyma cells include:

A

Cell Structure: Parenchyma cells are typically isodiametric (approximately equal in all dimensions) and have thin cell walls, a large central vacuole, and a prominent nucleus.

Function: Parenchyma cells perform diverse functions depending on their location within the plant. These functions include photosynthesis, storage of nutrients (such as starch, proteins, and lipids), secretion of enzymes and hormones, gas exchange, and wound healing.

Types of Parenchyma: There are several specialized types of parenchyma cells based on their location and function. For example, chlorenchyma cells are parenchyma cells containing chloroplasts and are involved in photosynthesis in leaves. In roots, storage parenchyma cells store starch and other reserve materials.

Plasticity: Parenchyma cells are highly adaptable and can differentiate into other types of cells, such as collenchyma or sclerenchyma cells, to provide structural support or defense in response to environmental stimuli or developmental cues.

In summary, parenchyma is a versatile plant tissue composed of unspecialized cells that perform various essential functions necessary for plant growth, metabolism, and adaptation to changing environmental conditions.

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5
Q

Collenchyma is another type of simple plant tissue found in the stems, leaves, and petioles of many herbaceous (non-woody) plants. It provides mechanical support and flexibility to the plant, especially in areas undergoing active growth and elongation.

Key characteristics of collenchyma tissue include:

A

Cell Structure: Collenchyma cells are elongated and have unevenly thickened primary cell walls, primarily made of cellulose and pectin. The thickening is localized at the corners or along the cell walls, giving them a polygonal shape.

Location: Collenchyma cells are typically found in the cortex of stems and petioles, as well as beneath the epidermis of leaves. They occur in regions where structural support is needed during plant growth and development.

Function: Collenchyma provides mechanical support and flexibility to young, growing plant organs. Unlike sclerenchyma, another type of supporting tissue, collenchyma cells are living cells and can elongate with the growth of the plant. They provide structural support while allowing for flexibility and expansion.

Types of Collenchyma: There are two main types of collenchyma: angular collenchyma, where the thickening occurs at the corners of the cells, and lamellar collenchyma, where the thickening is along the cell walls. The type of collenchyma present can vary depending on the plant species and the specific requirements of the tissue.

In summary, collenchyma is a specialized plant tissue that provides mechanical support and flexibility to young, growing plant organs. Its presence helps to maintain the structural integrity of the plant while accommodating the elongation and expansion associated with growth.

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6
Q

Sclerenchyma is a type of simple plant tissue that provides mechanical support and strength to various parts of the plant. It is composed of specialized cells known as sclerenchyma cells, which have thick, lignified secondary cell walls.

Key characteristics of sclerenchyma tissue include:

A

Cell Structure: Sclerenchyma cells are characterized by thick, lignified secondary cell walls that provide rigidity and strength. These walls are impregnated with lignin, a complex polymer that makes them hard and resistant to mechanical stress.

Cell Types: There are two main types of sclerenchyma cells: fibers and sclereids.

Fibers: Sclerenchyma fibers are long, slender cells with tapered ends. They occur in bundles and provide support and strength to plant organs such as stems, leaves, and vascular tissues.
Sclereids: Sclereids, also known as stone cells, are shorter, irregularly shaped cells that occur singly or in groups. They are found in various plant parts, including seed coats, fruit shells, and the outer layers of stems and leaves. Sclereids provide structural support and protection to these tissues.
Function: The primary function of sclerenchyma tissue is to provide mechanical support and reinforcement to plant organs. Sclerenchyma cells contribute to the rigidity and strength of the plant, helping it withstand mechanical stress, gravity, and environmental factors.

Lignification: Sclerenchyma cells undergo lignification, a process in which lignin is deposited in the secondary cell wall. Lignin provides rigidity and waterproofing to the cell wall, enhancing its structural integrity and resistance to decay and pathogens.

In summary, sclerenchyma is a specialized plant tissue composed of cells with thick, lignified secondary cell walls. It provides mechanical support and strength to various plant organs, contributing to the overall structural integrity and function of the plant.

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7
Q

Xylem

A

Xylem is a complex tissue responsible for the transport of water, minerals, and other dissolved substances from the roots to the aerial parts of the plant, including the stems, leaves, and flowers.
Components of xylem include tracheids, vessel elements, fibers, and parenchyma cells. Tracheids and vessel elements are elongated, dead cells with lignified walls that form tubes for water transport.
Water and minerals are absorbed by the roots and move through the xylem in an upward direction through a process called transpiration. Transpiration is driven by evaporation of water from the leaves and creates a negative pressure that pulls water up through the xylem.
Xylem also provides structural support to the plant and helps maintain its shape and rigidity.

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8
Q

Phloem:

A

Phloem is another complex tissue responsible for the transport of organic molecules, primarily sugars and other carbohydrates, from the leaves (sites of photosynthesis) to other parts of the plant, including the roots, stems, and fruits.
Phloem consists of sieve tube elements, companion cells, fibers, and parenchyma cells. Sieve tube elements are elongated cells with perforated end walls called sieve plates, which allow the flow of sap containing organic substances.
Sugar transport in the phloem occurs through a process called translocation. Sugars are actively transported into the sieve tube elements in the leaves and then move through the phloem to other parts of the plant, driven by a pressure gradient established by the loading and unloading of sugars.
Companion cells are associated with sieve tube elements and provide metabolic support and energy for phloem transport.
In summary, xylem and phloem are vascular tissues that work together to transport water, nutrients, and organic molecules throughout the plant body. Xylem transports water and minerals from the roots to the aerial parts, while phloem transports sugars and other organic compounds from the leaves to other parts of the plant. Their coordinated activities ensure the proper functioning and growth of the plant.

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9
Q

The terminal portion of the alimentary canal of a mammal is known as

A

the anus. The alimentary canal, also referred to as the gastrointestinal tract, is the pathway through which food passes during digestion. It includes several organs such as the mouth, esophagus, stomach, small intestine, and large intestine.

After food has been digested and nutrients have been absorbed in the small intestine, the remaining indigestible material, along with waste products, moves into the large intestine (colon). In the large intestine, water is absorbed, and the waste material becomes more solid. Eventually, this waste material, known as feces, moves into the rectum, which is the last portion of the large intestine.

The rectum serves as a temporary storage site for feces before they are eliminated from the body through the anus. The anus is the opening at the end of the alimentary canal through which feces are expelled from the body during defecation. It is lined with specialized tissue and muscles that help control the passage of feces out of the body.

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10
Q

An organism that lives on the remains of a dead plant is called a

A

An organism that lives on the remains of a dead plant is called a saprophyte or a saprotroph. These organisms obtain their nutrients by decomposing organic matter, such as dead plants, and breaking it down into simpler substances that they can absorb and utilize for growth and metabolism.

Saprophytes play a crucial role in ecosystem processes by recycling nutrients and organic matter, thereby contributing to the decomposition and decay of dead plant material. Examples of saprophytes include certain fungi, bacteria, and some types of protists. These organisms are essential for nutrient cycling and the overall health of ecosystem

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11
Q

Commensalism vs. Symbiosis:

A

Commensalism: In commensalism, one organism benefits from the relationship, while the other is neither harmed nor benefited. The organism that benefits is called the commensal, while the other organism is the host. An example is barnacles attached to whales.
Symbiosis: Symbiosis is a broader term that describes any close and long-term biological interaction between two different biological species. It can include mutualism, where both organisms benefit, or parasitism, where one organism benefits at the expense of the other.

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12
Q

Endoparasite vs. Ectoparasite:

A

Endoparasite: An endoparasite is an organism that lives inside the body of its host. It may live within the tissues, organs, or body cavities of the host. Endoparasites can cause diseases or harm to their hosts. Examples include tapeworms and certain types of bacteria.
Ectoparasite: An ectoparasite is an organism that lives on the external surface of its host. It may attach itself to the skin, feathers, fur, or scales of the host. Ectoparasites feed on the blood or tissues of the host and can cause irritation, discomfort, or disease. Examples include ticks, lice, and fleas.

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13
Q

Plasmolysis is a cellular phenomenon that occurs when a plant cell loses water and shrinks away from the cell wall due to osmotic water loss. It happens when a cell is placed in a hypertonic solution, where the concentration of solutes outside the cell is higher than inside the cell.

A

During plasmolysis:

Hypertonic Environment: When a plant cell is placed in a hypertonic solution, water moves out of the cell through osmosis. The cell’s cytoplasm and vacuole lose water, causing the cytoplasm to shrink away from the cell wall.

Shrinkage: As water exits the cell, the protoplast (the living part of the cell) contracts and pulls away from the rigid cell wall. The cell membrane detaches from the cell wall and may form a gap between the cell wall and the membrane.

Visible Changes: Plasmolysis is often visible under a microscope. The cell appears shrunken and the cell membrane may pull away from the cell wall, causing the cell to take on a wrinkled appearance.

Plasmolysis is reversible if the cell is placed in a hypotonic solution (where the concentration of solutes outside the cell is lower than inside the cell). In a hypotonic solution, water moves into the cell by osmosis, and the protoplast swells and returns to its original shape, pushing against the cell wall.

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14
Q

The axis vertebra, also known as the second cervical vertebra (C2), has several unique structures that distinguish it from other vertebrae in the spine. These structures include:

A

Odontoid Process (Dens): Perhaps the most distinctive feature of the axis vertebra is the odontoid process, also known as the dens. This is a large, tooth-like projection that extends superiorly from the body of the axis. The dens articulates with the anterior arch of the atlas (C1) and forms the pivot point around which the atlas and the head rotate.

Vertebral Foramen: Like other vertebrae, the axis vertebra has a vertebral foramen, which is a large opening in the center of the vertebra. The vertebral foramen of the axis accommodates the spinal cord as it passes through the spinal canal.

Spinous Process: The axis vertebra has a relatively short and bifid (split) spinous process that projects posteriorly from the vertebral arch. The spinous process provides attachment points for ligaments and muscles involved in movement and stability of the spine.

Transverse Processes: The axis vertebra has two transverse processes that project laterally from the vertebral arch. These processes serve as attachment sites for muscles and ligaments and play a role in stabilizing the vertebrae and supporting the movement of the head and neck.

Articular Facets: The axis vertebra has superior and inferior articular facets on its vertebral body and processes. These facets articulate with corresponding facets on adjacent vertebrae, contributing to the flexibility and range of motion of the cervical spine.

Overall, the unique structures of the axis vertebra, particularly the odontoid process, enable it to perform specialized functions in supporting the weight of the head and facilitating the movement of the cervical spine.

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15
Q

The atlas vertebra, also known as the first cervical vertebra (C1), has several distinctive features that set it apart from other vertebrae in the spine:

A

Ring-Shaped Structure: The atlas vertebra lacks a body and spinous process, giving it a unique ring-shaped structure. Instead of a body, it consists of two lateral masses connected by an anterior and a posterior arch.

Articular Facets: The lateral masses of the atlas have superior and inferior articular facets that articulate with corresponding facets on the occipital bone of the skull and the axis vertebra (C2), respectively. These articulations allow for flexion, extension, and rotation of the head and neck.

Atlanto-Occipital Joint: The superior articular facets of the atlas form the atlanto-occipital joints with the occipital condyles of the skull. These joints allow for nodding movements of the head (flexion and extension).

Atlanto-Axial Joint: The inferior articular facets of the atlas articulate with the odontoid process (dens) of the axis vertebra (C2) to form the atlanto-axial joints. These joints allow for rotation of the head from side to side (rotation).

Transverse Processes: The atlas vertebra has small transverse processes that project laterally from the lateral masses. These processes serve as attachment sites for muscles and ligaments involved in stabilizing the cervical spine and supporting head movements.

Overall, the atlas vertebra plays a critical role in supporting the weight of the head and facilitating its movements. Its unique structure and articulations allow for a wide range of motions in the neck, providing flexibility and stability to the cervical spine.

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16
Q

Niche:

A

A niche refers to the specific role or function of an organism within its ecosystem, including how it interacts with other organisms and its physical environment. It encompasses the resources an organism uses, its interactions with other species, and its adaptations to its environment.
The niche of an organism includes its habitat, food sources, behaviors, and reproductive strategies. It also includes its tolerance for environmental conditions such as temperature, humidity, and pH.
Each species occupies a unique niche within its ecosystem, and niches may overlap or be shared among multiple species. The concept of the niche helps to explain how species coexist and interact in complex ecosystems.

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17
Q

Microhabitat:

A

A microhabitat refers to a small-scale, localized environment within a larger habitat that has distinct characteristics or conditions that differ from the surrounding area.
Microhabitats may vary in size and can include areas such as the underside of rocks, the leaf litter layer on the forest floor, the bark of trees, or the surface of a pond.
Organisms may occupy specific microhabitats within their larger habitat to meet their specific ecological needs, such as foraging, nesting, sheltering, or thermoregulation.
Microhabitats can support unique communities of organisms adapted to the specific conditions found within them, and they contribute to the overall biodiversity and complexity of ecosystems.

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18
Q

A Secchi disc

A

A Secchi disc is used to measure water transparency or clarity in bodies of water, such as lakes, rivers, and oceans. It consists of a circular, flat, white disk with alternating black and white quadrants. The Secchi disc is lowered into the water until it disappears from sight, and the depth at which it disappears, known as the Secchi depth, is recorded.

The Secchi depth provides an indication of water transparency by measuring the depth at which light penetration is reduced due to scattering and absorption by suspended particles, algae, and dissolved substances in the water column. A shallower Secchi depth suggests lower water clarity, while a deeper Secchi depth indicates higher water clarity.

Secchi disc measurements are commonly used by scientists, environmental researchers, and citizen scientists to monitor changes in water quality, assess trophic status (eutrophication), and track trends in water clarity over time. They provide valuable information for understanding ecosystem dynamics, habitat suitability, and the overall health of aquatic environments.

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19
Q

Several devices are used to measure tides, waves, and rainfall, each tailored to the specific parameter being measured:

A

Tides: Tides are typically measured using tide gauges or tidal gauges. These gauges record the changes in water level caused by the gravitational forces exerted by the moon and the sun. Modern tide gauges often use pressure sensors, acoustic sensors, or float-based systems to measure water level changes relative to a reference point. Tide gauges can be installed along coastlines, harbors, estuaries, and other coastal areas to monitor tidal patterns and variations over time.

Waves: Waves in the ocean or other bodies of water are measured using wave buoys or wave sensors. Wave buoys are equipped with sensors that measure parameters such as wave height, wave period, and wave direction. These buoys are anchored in the water and transmit data to shore-based stations via satellite or radio communications. Wave sensors can also be mounted on fixed structures such as piers or offshore platforms to monitor wave conditions in real-time.

Rainfall: Rainfall is measured using rain gauges or pluviometers. These devices collect and measure the amount of precipitation that falls over a specific area during a given period. Traditional rain gauges consist of a cylindrical container with a funnel-shaped top that directs rainfall into a graduated measuring tube. The collected rainfall is then measured in millimeters or inches. Automated rain gauges may use electronic sensors to measure rainfall intensity and duration, and they can transmit data wirelessly to data loggers or monitoring stations.

Overall, these devices play a crucial role in monitoring and understanding hydrological processes, weather patterns, and environmental conditions in various aquatic and terrestrial ecosystems.

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20
Q

Gene:

A

A gene is a specific segment of DNA that contains the genetic instructions for synthesizing a particular protein or RNA molecule.
Genes determine various traits, characteristics, and functions of an organism, such as eye color, hair texture, and enzyme production.
Genes are the units of heredity and are passed from parents to offspring during reproduction.
Each gene is composed of a specific sequence of nucleotides (the building blocks of DNA or RNA) that encode the information necessary for protein synthesis.
Mutations in genes can lead to genetic variations and may result in changes to an organism’s traits or predisposition to certain diseases.

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21
Q

Chromosome:

A

A chromosome is a long, thread-like structure composed of DNA and associated proteins (histones) found in the nucleus of eukaryotic cells.
Chromosomes contain many genes arranged linearly along the DNA molecule.
The number and structure of chromosomes vary among different species. For example, humans typically have 46 chromosomes (23 pairs), while other organisms may have more or fewer chromosomes.
Chromosomes undergo replication and condensation during cell division, ensuring that each daughter cell receives the correct number and complement of chromosomes.
In addition to genes, chromosomes also contain other DNA sequences, such as regulatory elements and non-coding regions, which play roles in gene expression and genome organization.

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22
Q

Gastrin is not an enzyme. Gastrin is a hormone that is produced by the stomach and plays a key role in regulating the secretion of gastric acid (hydrochloric acid) and pepsinogen, which is the inactive precursor of the enzyme pepsin.

Pepsin, chymotrypsin, and trypsin are all enzymes involved in the digestion of proteins:

A

Pepsin: Pepsin is an enzyme that is produced in the stomach by the chief cells (chief or peptic cells). Pepsinogen, the inactive form of pepsin, is secreted into the stomach, where it is activated by the acidic environment (low pH) of the stomach. Pepsin is responsible for breaking down proteins into smaller peptides by hydrolyzing peptide bonds between amino acids.

Chymotrypsin: Chymotrypsin is an enzyme produced in the pancreas and secreted into the small intestine. It is synthesized and secreted in its inactive form, prochymotrypsin, which is activated by trypsin. Chymotrypsin is responsible for hydrolyzing peptide bonds in proteins, particularly those involving aromatic or large hydrophobic amino acids.

Trypsin: Trypsin is another enzyme produced in the pancreas and secreted into the small intestine. It is synthesized and secreted as an inactive precursor called trypsinogen, which is activated by enterokinase, an enzyme produced by the intestinal mucosa. Trypsin is responsible for hydrolyzing peptide bonds in proteins, particularly those involving the basic amino acids arginine and lysine.

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23
Q

amylase

A

Yes, amylase is an enzyme. Amylase is a type of enzyme that catalyzes the hydrolysis of starch and glycogen into smaller carbohydrate molecules, such as maltose, maltotriose, and dextrins. It is produced by various organisms, including humans, animals, plants, and microorganisms.

In humans, amylase is produced primarily in the salivary glands and pancreas. Salivary amylase, also known as ptyalin, is secreted into the mouth and begins the process of breaking down starches in food into simpler sugars (such as maltose) during chewing and digestion. Pancreatic amylase is secreted into the small intestine and continues the digestion of starches into smaller carbohydrate molecules.

Amylase works by catalyzing the hydrolysis reaction, where a water molecule is used to break the glycosidic bonds between glucose molecules in starch or glycogen, resulting in the formation of smaller carbohydrate molecules.

Overall, amylase plays a crucial role in the digestion of carbohydrates and the release of energy from food in various organisms.

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24
Q

In roots and stems, the region of active cell division is known as the meristematic tissue or meristem. Meristematic tissue is composed of undifferentiated cells that have the capacity to divide and differentiate into specialized cell types, allowing for the growth and development of the plant.

A

There are two primary types of meristematic tissue found in roots and stems:

Apical Meristem:

The apical meristem is located at the tips of roots and shoots (stems). It is responsible for primary growth, which involves the lengthening of the plant body.
In roots, the apical meristem is found at the root tip, protected by the root cap. It continuously produces new cells that differentiate into various root tissues, including the root cap, epidermis, cortex, and vascular tissues.
In stems, the apical meristem is found at the shoot tip, also known as the terminal bud. It produces new cells that differentiate into the primary tissues of the stem, including the epidermis, cortex, and vascular tissues.
Lateral Meristem:

The lateral meristem is responsible for secondary growth, which involves the increase in girth or diameter of the plant body.
In stems, the lateral meristem is known as the vascular cambium and cork cambium. The vascular cambium produces secondary xylem (wood) towards the inside and secondary phloem towards the outside, contributing to the growth of woody stems.
In roots, the lateral meristem is less common but may be present in certain species as the pericycle. The pericycle can give rise to lateral roots or secondary growth in roots.
Both types of meristematic tissue are crucial for the growth and development of roots and stems, allowing plants to increase in length and girth over time.

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25
Q

piliferous layer

A

The term “piliferous layer” refers to a specialized region in the root system of plants where root hairs originate. Root hairs are tiny, hair-like structures that extend from the surface of the root epidermis and play a crucial role in absorbing water and nutrients from the soil.

The piliferous layer is not a distinct anatomical layer but rather a zone within the root epidermis where root hairs develop. It consists of epidermal cells that give rise to root hairs. As new root cells differentiate and mature, some of them elongate and differentiate into root hairs in this region.

Root hairs significantly increase the surface area of the root system, allowing for greater absorption of water and minerals from the soil. They form a close association with soil particles and water, facilitating the uptake of essential nutrients for plant growth and development.

Overall, the piliferous layer is a critical component of the root system, contributing to the plant’s ability to efficiently acquire water and nutrients from the surrounding soil environment.

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26
Q

periderm

A

The periderm is the outer protective tissue layer in woody plants that replaces the epidermis in older stems and roots undergoing secondary growth. The periderm is composed of three distinct layers: cork cambium (phellogen), cork cells (phellem), and phelloderm.

Cork Cambium (Phellogen): The cork cambium is a lateral meristem responsible for producing cork cells outwardly and phelloderm inwardly. It is a layer of actively dividing cells that form the periderm.

Cork Cells (Phellem): Cork cells, also known as phellem, are dead, lignified cells produced by the cork cambium. They are tightly packed and provide protection to the underlying tissues.

Phelloderm: Phelloderm is a layer of parenchyma cells produced by the cork cambium toward the inner side of the periderm. It functions in storage and support.

The periderm, or corky layer, replaces the epidermis in older stems and roots as they undergo secondary growth. It provides protection against mechanical injury, water loss, and invasion by pathogens. This layer is particularly prominent in woody plants and is essential for their survival and structural integrity.

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27
Q
A
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28
Q

Rough and spiny pollen grains are typically associated with plants that undergo ___________ pollination

A

Rough and spiny pollen grains are typically associated with plants that undergo entomophilous pollination, which is pollination carried out by insects. Insects like bees, beetles, and flies often visit flowers to collect pollen and nectar. The rough and spiny texture of the pollen grains helps them adhere to the bodies of insects, facilitating their transfer from one flower to another during the pollination process.

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29
Q

The excretory system in the human body is responsible for removing waste products and excess substances from the bloodstream, maintaining homeostasis, and regulating various physiological processes. The primary organs involved in excretion include:

A

Kidneys: The kidneys are the main excretory organs of the body. They filter blood to remove waste products such as urea, creatinine, and excess ions, while also regulating water and electrolyte balance. The kidneys produce urine, which is transported to the bladder for storage and eventual elimination.
Urinary Bladder: The urinary bladder is a muscular sac that stores urine temporarily until it is expelled from the body during urination.
Ureters: Ureters are narrow tubes that connect the kidneys to the urinary bladder. They transport urine from the kidneys to the bladder using peristaltic contractions.
Urethra: The urethra is a tube that carries urine from the bladder to the outside of the body during urination.
Skin: While not an organ exclusively dedicated to excretion, the skin plays a role in excreting waste products through sweat. Sweat glands in the skin release sweat, which contains water, salts, and small amounts of metabolic waste products such as urea and ammonia.
Lungs: The lungs excrete carbon dioxide, a waste product of cellular respiration, during the process of breathing. Carbon dioxide is removed from the bloodstream and expelled from the body during exhalation.

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30
Q

The ciliary muscle is a ring of smooth muscle fibers located in the eye, specifically within the ciliary body. Its primary function is to control the shape of the lens, which in turn allows the eye to focus on objects at different distances, a process known as accommodation.

Here’s how the ciliary muscle affects the lens:

A

Relaxation: When the ciliary muscle is relaxed, it pulls outward, causing the suspensory ligaments (zonules) that attach to the lens to become taut. This stretches the lens, making it thinner and less curved.
Distant Vision: In distant vision, when the ciliary muscle is relaxed, the lens is stretched and flattened. This allows light rays from distant objects to focus properly on the retina without being overly refracted.
Contraction: When the eye needs to focus on nearby objects, the ciliary muscle contracts. This reduces tension on the suspensory ligaments, allowing the lens to become thicker and more rounded.
Near Vision: In near vision, the ciliary muscle contraction causes the lens to become more curved. This increased curvature increases the refractive power of the lens, allowing the eye to focus light rays from nearby objects onto the retina.
By adjusting the shape of the lens through contraction and relaxation, the ciliary muscle enables the eye to maintain clear vision across a range of distances, from far to near. This process of accommodation is essential for visual tasks such as reading, viewing digital screens, and other activities that require focusing on objects at different distances.

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31
Q

River Blindness (Onchocerciasis):

A

Vector: Blackflies (Simulium spp.).
Control Measures: Insecticide spraying, larviciding, use of larvivorous fish, and environmental modification to reduce breeding sites. Mass drug administration with ivermectin is also used to treat affected populations.

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32
Q

Malaria:

A

Vector: Anopheles mosquitoes (Anopheles spp.).
Control Measures: Use of insecticide-treated bed nets, indoor residual spraying with insecticides, larval control through environmental management (e.g., draining stagnant water), and community-based malaria control programs. In some cases, larvicides may also be used.

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33
Q

Polio

A

Vector: Poliovirus is transmitted primarily through the fecal-oral route, rather than by an arthropod vector.
Control Measures: Immunization through polio vaccines, including oral polio vaccine (OPV) and inactivated polio vaccine (IPV). Vaccination campaigns, surveillance, and monitoring for poliovirus circulation are also important strategies.

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34
Q

Cholera

A

Vector: Cholera is not transmitted by vectors but through contaminated food and water, primarily due to the bacterium Vibrio cholerae.
Control Measures: Improving water and sanitation infrastructure, ensuring access to clean drinking water, promoting hygiene practices (such as handwashing), proper disposal of human waste, and timely treatment of infected individuals to prevent further transmission.

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35
Q

Bilharzia (Schistosomiasis):

A

Vector: Freshwater snails of the genus Biomphalaria (Schistosoma mansoni), Oncomelania (Schistosoma japonicum), or Bulinus (Schistosoma haematobium).
Control Measures: Snail control through environmental modification, use of molluscicides to kill snails, reducing contact with contaminated water (e.g., by providing safe water sources and promoting protective behaviors), and mass drug administration with praziquantel to treat infected individuals.

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36
Q

The mammalian brain is composed of several distinct regions, each with its own specialized functions. Here are the general biological functions of some key parts of the mammalian brain:

A

Cerebrum:
The cerebrum is the largest part of the brain and is responsible for higher-order brain functions, including conscious thought, voluntary movement, memory, language, perception, and sensory processing.
It is divided into two cerebral hemispheres, each further divided into lobes (frontal, parietal, temporal, and occipital lobes) that specialize in different functions.
Cerebellum:
The cerebellum is located beneath the cerebrum and is primarily involved in motor coordination, balance, and posture.
It receives information from sensory systems, spinal cord, and other parts of the brain to coordinate voluntary movements and maintain equilibrium.
Brainstem:
The brainstem is located at the base of the brain and consists of the midbrain, pons, and medulla oblongata.
It regulates basic life functions such as heart rate, breathing, blood pressure, and digestion.
The brainstem also serves as a conduit for sensory and motor pathways between the brain and spinal cord.
Hypothalamus:
The hypothalamus is a small region located below the thalamus and plays a crucial role in maintaining homeostasis by regulating various physiological processes, including body temperature, hunger, thirst, sleep-wake cycles, and hormone secretion from the pituitary gland.
Thalamus:
The thalamus serves as a relay station for sensory information traveling to and from the cerebral cortex.
It processes and relays sensory signals (except for olfaction) to the appropriate regions of the cerebral cortex for further processing and interpretation.
Amygdala:
The amygdala is located deep within the temporal lobes and is involved in the processing of emotions, emotional memory, and the perception of threat or danger.
It plays a critical role in the “fight or flight” response and the regulation of emotional responses to stimuli.
Hippocampus:
The hippocampus, located within the temporal lobes, is involved in the formation and consolidation of long-term declarative memories (memory for facts and events).
It also plays a role in spatial navigation and memory recall.
These brain regions work together to regulate various physiological and cognitive functions, ensuring the overall functioning and survival of the organism.

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37
Q

Paramecium is a single-celled organism belonging to the phylum Ciliophora. Here are some key points about Paramecium:

A

Structure: Paramecium is characterized by its elongated, slipper-like shape and is covered with numerous hair-like structures called cilia, which it uses for movement and feeding. It has a well-defined cell membrane and a pellicle that gives it structural support.
Habitat: Paramecium is found in freshwater environments, such as ponds, lakes, and slow-moving streams. It thrives in nutrient-rich, oxygenated water.
Feeding: Paramecium is a heterotrophic organism, meaning it feeds on organic matter. It uses its cilia to sweep food particles, such as bacteria, algae, and small protozoans, into its oral groove. Food particles are engulfed into food vacuoles, where digestion occurs.
Reproduction: Paramecium reproduces asexually by binary fission, where the cell divides longitudinally into two daughter cells. It can also undergo sexual reproduction through a process called conjugation, where genetic material is exchanged between two mating cells.
Contractile Vacuole: Paramecium possesses contractile vacuoles, which are responsible for regulating water content and removing excess water from the cell. This helps maintain osmotic balance in a freshwater environment.
Sensory Structures: Paramecium has sensory structures, including cilia and specialized organelles called trichocysts, which help detect environmental changes and respond to stimuli.
Nucleus: Paramecium contains two types of nuclei: a large macronucleus and one or more small micronuclei. The macronucleus is involved in metabolic activities and gene expression, while the micronucleus is involved in sexual reproduction and genetic exchange during conjugation.
Role in Ecosystem: Paramecium serves as an important component of freshwater ecosystems, playing a role in nutrient cycling and serving as prey for larger organisms.

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38
Q

Paramecium

A

Paramecium and other ciliated protozoans, the gullet is lined with cilia. These cilia beat rhythmically to create water currents that sweep food particles into the gullet for ingestion. The coordinated movement of cilia helps propel the food vacuole along the gullet and eventually into the cell for digestion and nutrient absorption.

39
Q

Benedict’s Test

A

Benedict’s reagent is used to test for the presence of reducing sugars, such as glucose and fructose. In this test, the sample is mixed with Benedict’s reagent and heated in a water bath. If reducing sugars are present, they react with the copper ions in the reagent, forming a colored precipitate. The color change ranges from blue (no reducing sugar present) to green, yellow, orange, or red (increasing concentration of reducing sugar).

40
Q

Fehling’s Test

A

Fehling’s solution is another test used to detect reducing sugars. It consists of two separate solutions: Fehling’s A (copper(II) sulfate) and Fehling’s B (sodium potassium tartrate in sodium hydroxide). When mixed together and heated with a reducing sugar, a reddish-brown precipitate of copper(I) oxide forms.

41
Q

Tollens’ Test

A

Tollens’ reagent, also known as silver mirror test, is used to detect the presence of reducing sugars that can be oxidized. Tollens’ reagent is prepared by mixing ammonium hydroxide, silver nitrate, and a small amount of sodium hydroxide. When a reducing sugar is present, it reacts with Tollens’ reagent to reduce the silver ions, resulting in the formation of a silver mirror on the inside of the reaction tube.

42
Q

Barfoed’s Test

A

Barfoed’s reagent is used to distinguish between monosaccharides and disaccharides. It is similar to Benedict’s test but is specific to monosaccharides. Barfoed’s reagent contains copper acetate and acetic acid, and when heated, it forms a reddish-brown precipitate in the presence of monosaccharides.

43
Q

When the ciliary muscle contracts, it causes the lens of the eye to change shape, which is a process known as accommodation.

A

Specifically, the contraction of the ciliary muscle causes the suspensory ligaments attached to the lens to relax. As a result, the lens becomes more rounded and thicker, increasing its refractive power. This adjustment allows the eye to focus on nearby objects, a process known as near vision accommodation. Conversely, when the ciliary muscle relaxes, the lens becomes flatter, allowing the eye to focus on distant objects.

44
Q

Molisch’s Test

A

Molisch’s test is a general test for the presence of all types of carbohydrates. It involves the addition of alpha-naphthol followed by concentrated sulfuric acid to the sample. Carbohydrates react with the acid to form a purple ring at the interface between the two layers.

45
Q

The anal pore of Paramecium

A

The anal pore of Paramecium is a structure used for waste elimination. Paramecia are single-celled organisms that have a contractile vacuole system responsible for regulating water balance and expelling excess water. The anal pore is where undigested food particles and other waste products are expelled from the cell. It acts as an exit point for waste materials that have been processed and collected within the cell’s food vacuoles.

46
Q

If the Benedict’s solution remains blue after performing a test for sugars

A

If the Benedict’s solution remains blue after performing a test for sugars, it indicates that there is no reducing sugar present in the solution. This means that the sugar tested does not contain any reducing sugar, such as glucose or fructose. Instead, it may contain non-reducing sugars like sucrose or starch, which do not react with Benedict’s solution to produce a color change.

47
Q

If Fehling’s solution A and B remain blue after boiling

A

If Fehling’s solution A and B remain blue after boiling, it indicates that there is no reducing sugar present in the solution being tested. Fehling’s solution is used to detect the presence of reducing sugars, such as glucose or fructose. When a reducing sugar is present, Fehling’s solution changes color from blue to brick-red or yellowish-brown upon boiling, due to the reduction of copper ions in the solution by the sugar. If the solution remains blue, it suggests the absence of reducing sugars in the sample.

48
Q

Reducing sugars are carbohydrates that have a free aldehyde or ketone functional group, which allows them to act as reducing agents. Some common types of reducing sugars include:

A

Reducing sugars are carbohydrates that have a free aldehyde or ketone functional group, which allows them to act as reducing agents. Some common types of reducing sugars include:

Glucose: Glucose is a simple sugar and one of the most abundant reducing sugars found in nature. It is the primary source of energy for living organisms.
Fructose: Fructose is another simple sugar commonly found in fruits, honey, and some vegetables. It is a reducing sugar due to its ketone functional group.
Galactose: Galactose is a monosaccharide that is less common than glucose and fructose but is still considered a reducing sugar.
Maltose: Maltose is a disaccharide composed of two glucose molecules joined by a glycosidic bond. It is a reducing sugar because it can be hydrolyzed to form glucose.
Lactose: Lactose is a disaccharide composed of one glucose molecule and one galactose molecule. It is found in milk and dairy products and is a reducing sugar.

49
Q

Non-reducing sugars are carbohydrates that lack a free aldehyde or ketone group and therefore cannot act as reducing agents. They include:

A

Sucrose: Sucrose, also known as table sugar, is a disaccharide composed of one glucose molecule and one fructose molecule. While both glucose and fructose are reducing sugars individually, the glycosidic bond that links them in sucrose prevents it from acting as a reducing sugar.
Trehalose: Trehalose is a disaccharide composed of two glucose molecules linked together. Similar to sucrose, the glycosidic bond between the two glucose units prevents trehalose from acting as a reducing sugar.
Cellobiose: Cellobiose is a disaccharide composed of two glucose molecules joined by a beta-glycosidic bond. Like sucrose and trehalose, the glycosidic bond in cellobiose makes it a non-reducing sugar.
These non-reducing sugars are commonly found in various plant tissues and food products. They play important roles in energy storage and structural support within cells and organisms.

50
Q

Alkaline pyrogallol

A

Alkaline pyrogallol is commonly used in experiments to absorb oxygen from a gas mixture. Pyrogallol is a compound that readily reacts with oxygen in the presence of an alkali solution.

In laboratory settings, alkaline pyrogallol is often used in experiments to measure the rate of respiration in organisms or to determine the oxygen content in a gas sample. The pyrogallol solution is typically prepared by dissolving pyrogallol crystals in an alkaline solution, such as sodium hydroxide (NaOH) or potassium hydroxide (KOH).

During the experiment, the gas sample containing oxygen is bubbled through the alkaline pyrogallol solution. The pyrogallol reacts with the oxygen in the gas, causing it to be absorbed by the solution. As oxygen is consumed, the color of the pyrogallol solution changes from clear to brown due to the formation of a brown compound, such as pyrogallolquinone.

The rate at which oxygen is absorbed by the alkaline pyrogallol solution can be used to calculate the rate of respiration in organisms or to determine the oxygen concentration in the gas sample. This method is often employed in biochemical and physiological studies to investigate oxygen consumption and metabolic activity.

51
Q

In a photosynthesis experiment, alkaline pyrogallol can be used to

A

In a photosynthesis experiment, alkaline pyrogallol can be used to determine the rate of oxygen production by photosynthetic organisms. When photosynthesis occurs, oxygen is released as a byproduct of the light-dependent reactions.

To measure the rate of oxygen production, the photosynthetic organism (such as a plant or algae) is placed in a sealed container with a solution containing alkaline pyrogallol. As photosynthesis proceeds, oxygen is produced by the organism and accumulates in the container.

The alkaline pyrogallol solution serves to absorb the oxygen produced by photosynthesis. As oxygen is absorbed, the pyrogallol solution undergoes a color change, turning from clear to brown. The rate of color change indicates the rate of oxygen production by the photosynthetic organism.

By monitoring the color change over time, researchers can determine the rate at which oxygen is being produced through photosynthesis. This information helps in studying the efficiency of photosynthesis under different experimental conditions, such as varying light intensity, temperature, or carbon dioxide concentration.

52
Q

Plumble

A

The micropyle is a small opening in the ovule of a seed plant. It serves as the point of entry for the pollen tube during fertilization. The structure near the micropyle, referred to as the plumble, likely has some significance in the seed’s development or function, possibly related to germination or early growth stages.

53
Q

Fruits can be categorized into various types based on their characteristics. Here are some common types of fruits:

A

Simple fruits: These fruits develop from a single ovary of a single flower. Examples include apples, cherries, and tomatoes.
Aggregate fruits: Aggregate fruits form from multiple ovaries of a single flower. Examples include strawberries and raspberries.
Multiple fruits: Multiple fruits develop from the ovaries of multiple flowers that are closely packed together. Pineapples and figs are examples of multiple fruits.
Accessory fruits: These fruits develop from tissues other than the ovary, such as receptacle or floral parts. Examples include apples and pears, where the core is part of the flower receptacle.
Dry fruits: Dry fruits have a dry pericarp (outer layer) at maturity. Examples include nuts, grains, and beans.
Fleshy fruits: Fleshy fruits have a soft, succulent pericarp. They can be further classified into drupes (e.g., peaches, plums), berries (e.g., grapes, bananas), and hesperidia (e.g., oranges, lemons).

54
Q

Schizocarp

A

A schizocarp is a type of dry fruit that develops from a compound ovary and typically splits into two or more one-seeded segments called mericarps at maturity. Each mericarp contains a single seed. Schizocarps are characteristic of the Apiaceae family, which includes plants like parsley, dill, and carrots.

When the schizocarp ripens, it breaks apart into its individual mericarps, allowing the seeds to disperse. This dispersal mechanism helps the plant spread its seeds over a wider area, increasing the chances of successful germination and growth in new locations.

Schizocarps come in various shapes and sizes, and they play an essential role in the reproduction and propagation of plants within the Apiaceae family.

55
Q

caryopsis

A

A caryopsis is a type of fruit in which the seed coat is fused with the fruit wall, making it difficult to separate them. This type of fruit is commonly found in grasses such as wheat, rice, maize, and barley. In a caryopsis, the seed is fully enclosed within the fruit wall, and the fruit does not split open when mature.

56
Q

Samara

A

samara is a type of dry fruit characterized by a papery wing surrounding the seed. This wing helps the fruit to disperse by wind. Common examples of plants that produce samaras include maple trees, ash trees, and elm trees.

57
Q

Follicle

A

Follicle: A follicle is a dry fruit that develops from a single carpel and splits open along one side to release its seeds. The seeds are attached to the inner wall of the follicle. Milkweed is an example of a plant that produces follicles.

58
Q

Samara and follicle

A

These two types of fruit differ in their structure and mechanism of seed dispersal. Samaras are often dispersed by wind due to their wing-like structures, while follicles rely on various methods, including wind, water, or animal dispersal, depending on the plant species.

59
Q

Nut

A

A nut is a type of fruit composed of a hard shell surrounding a seed or seeds. Nuts are characterized by their hard, woody shell that does not split open at maturity to release the seeds. Instead, the seeds remain enclosed within the shell until it is cracked open.

Nuts are produced by a variety of plants, including trees and shrubs. Examples of true nuts include acorns (from oak trees), chestnuts, and hazelnuts. In botanical terms, nuts are a specific type of fruit classified as indehiscent fruits, meaning they do not naturally split open to release their seeds.

Nuts are valued for their nutritional content, often containing healthy fats, protein, vitamins, and minerals. They are commonly consumed as a snack or used in cooking, baking, and as ingredients in various dishes and recipes.

60
Q

Soil can be broadly classified into several types based on their composition, texture, and other characteristics. Here are some common types of soil and their characteristics:

A

Sandy Soil:
Characteristics: Sandy soil has large particles and is gritty to the touch. It does not hold water well and tends to drain quickly. Sandy soil warms up quickly in spring, making it suitable for early planting.
Clay Soil:
Characteristics: Clay soil has small particles and feels sticky when wet. It holds water well but drains slowly, leading to poor aeration. Clay soil can become hard and compacted when dry, making it difficult for plant roots to penetrate.
Loamy Soil:
Characteristics: Loamy soil is a balanced mixture of sand, silt, and clay particles. It has good drainage, retains moisture well, and is fertile. Loamy soil is considered ideal for gardening and agriculture because it provides a suitable environment for plant growth.
Silt Soil:
Characteristics: Silt soil has medium-sized particles that feel smooth and floury when dry. It has good water retention and drainage properties, making it fertile and suitable for agriculture.
Peaty Soil:
Characteristics: Peaty soil is high in organic matter and forms in waterlogged, acidic conditions, such as bogs and marshes. It is dark brown or black in color and retains moisture well. Peaty soil is nutrient-rich but may be low in essential minerals.
Chalky Soil:
Characteristics: Chalky soil contains a high proportion of calcium carbonate and is alkaline in nature. It is typically light and free-draining but may be shallow in some areas. Chalky soil may have limited fertility due to its alkaline pH.
Sandy Loam Soil:
Characteristics: Sandy loam soil is a mixture of sand, silt, and clay, with a higher proportion of sand particles. It has good drainage, retains moisture, and is easy to work with. Sandy loam soil is suitable for a wide range of plants and crops.

61
Q

Hormones are chemical messengers produced by various glands and tissues in the body. They regulate numerous physiological processes and help maintain homeostasis. Here are some common hormones in biology and where they are secreted:

A

Insulin:
Secreted by: Pancreas (specifically, the beta cells in the islets of Langerhans).
Function: Regulates blood glucose levels by promoting the uptake of glucose into cells and the storage of excess glucose as glycogen in the liver and muscles.
Glucagon:
Secreted by: Pancreas (specifically, the alpha cells in the islets of Langerhans).
Function: Increases blood glucose levels by stimulating the breakdown of glycogen in the liver and the release of glucose into the bloodstream.
Thyroid Hormones (T3 and T4):
Secreted by: Thyroid gland.
Function: Regulate metabolism, growth, and development. They also play a role in maintaining body temperature and energy levels.
Cortisol:
Secreted by: Adrenal glands (specifically, the adrenal cortex).
Function: Regulates metabolism, immune function, and stress response. Cortisol also helps the body respond to stressful situations by increasing blood sugar levels and suppressing inflammation.
Adrenaline (Epinephrine):
Secreted by: Adrenal glands (specifically, the adrenal medulla).
Function: Initiates the body’s “fight or flight” response to stress by increasing heart rate, dilating airways, and redirecting blood flow to vital organs.
Estrogen:
Secreted by: Ovaries (in females) and small amounts by the adrenal glands.
Function: Regulates the menstrual cycle, promotes the development of secondary sexual characteristics, and maintains bone density.
Progesterone:
Secreted by: Ovaries (in females) and small amounts by the adrenal glands.
Function: Prepares the uterus for implantation of a fertilized egg and helps maintain pregnancy.
Testosterone:
Secreted by: Testes (in males) and small amounts by the adrenal glands (in both males and females).
Function: Promotes the development of male reproductive organs and secondary sexual characteristics. Testosterone also plays a role in sperm production and libido.

62
Q

There are several common methods used in biology to assess soil erosion:

A

Field Surveys: Field surveys involve direct observation and measurement of soil erosion features in the field. Researchers examine the extent of soil loss, the depth of erosion, and the characteristics of eroded soil. This method provides valuable qualitative and quantitative data on soil erosion patterns.
Sediment Traps: Sediment traps are structures designed to capture sediment runoff from erosion-prone areas. These traps collect sediment-laden water, allowing researchers to quantify the amount of soil eroded from a given area over time.
Terraces and Contour Plowing: Terraces and contour plowing are soil conservation practices used to mitigate soil erosion on sloping terrain. Terraces are horizontal or gently sloping embankments constructed along the contour lines of a hillside to reduce water runoff and soil erosion. Contour plowing involves plowing and planting crops along the contour lines of the land to minimize soil disturbance and prevent water from flowing downhill.
Vegetative Cover: Maintaining vegetative cover, such as grasses, shrubs, and trees, is an effective method to prevent soil erosion. Plant roots help bind soil particles together, reducing the risk of erosion by wind and water. Vegetative cover also intercepts rainfall, reducing the impact of raindrops on the soil surface.
Soil Erosion Models: Soil erosion models use mathematical equations and computer simulations to predict soil erosion rates based on factors such as soil type, slope steepness, land use, and precipitation patterns. These models provide valuable insights into the factors contributing to soil erosion and help land managers develop erosion control strategies.
Rainfall Simulators: Rainfall simulators are experimental setups used to simulate natural rainfall events under controlled conditions. These simulators allow researchers to study the effects of rainfall intensity, duration, and soil management practices on soil erosion rates. By varying experimental parameters, researchers can assess the effectiveness of different erosion control measures.
Remote Sensing: Remote sensing techniques, such as satellite imagery and aerial photography, are valuable tools for monitoring soil erosion over large geographic areas. Remote sensing data can be used to identify areas prone to erosion, assess changes in land cover and land use, and monitor erosion control measures implemented on the landscape.

63
Q

Bacteria in legume nodules

A

they play a crucial role in fixing atmospheric nitrogen. Legume plants form a symbiotic relationship with nitrogen-fixing bacteria called rhizobia. These bacteria reside within specialized structures called root nodules, which form on the roots of legume plants.

Inside the root nodules, rhizobia convert atmospheric nitrogen (N2) into ammonia (NH3) through a process called nitrogen fixation. This ammonia is then converted into ammonium ions (NH4+) that can be used by the plant to synthesize amino acids, proteins, and other nitrogen-containing compounds essential for growth and development.

The process of nitrogen fixation is energetically demanding and requires an anaerobic environment, meaning it occurs in the absence of oxygen. To create the necessary conditions for nitrogen fixation, legume plants regulate oxygen levels within the nodules by producing leghemoglobin, a protein that binds and sequesters oxygen, creating a microaerobic environment suitable for nitrogenase, the enzyme responsible for nitrogen fixation.

64
Q

Nitrogen putrefying bacteria

A

Nitrogen putrefying bacteria are microorganisms that play a role in the process of putrefaction, which is the decomposition of organic matter, particularly proteins, by bacteria and fungi. While putrefaction primarily involves the breakdown of proteins, it also involves the release of nitrogen in various forms, including ammonia (NH3) and organic nitrogen compounds.

Putrefying bacteria, such as certain species of Proteus, Clostridium, and Pseudomonas, are involved in the decomposition of proteins and organic matter. These bacteria break down complex nitrogen-containing compounds found in organic material, such as proteins and amino acids, into simpler nitrogen compounds like ammonia.

During putrefaction, proteins are broken down into amino acids, and then further broken down into simpler nitrogen-containing compounds. Putrefying bacteria facilitate these biochemical processes through enzymatic action, ultimately leading to the release of nitrogenous compounds into the environment.

While putrefying bacteria play a role in the nitrogen cycle by decomposing organic matter and releasing nitrogenous compounds, they are also involved in the breakdown of other organic compounds, contributing to the recycling of nutrients in ecosystems. However, excessive putrefaction can lead to unpleasant odors and the release of potentially harmful substances into the environment.

65
Q

When crossbreeding a tall variety (Tt) of maize with a short variety (tt) where T represents the dominant allele for tallness and t represents the recessive allele for shortness, the Punnett square is used to determine the ratio of tall to short plants in the offspring.

A

The genotypes of the parents are:

Tall variety (Tt) x Short variety (tt)

The possible gametes from the tall variety are T and t, and from the short variety is only t.

The Punnett square for this cross would look like:

66
Q

Rennin

A

Rennin, also known as chymosin, is an enzyme primarily found in the stomachs of young mammals, including humans. Its main function is to curdle milk by coagulating the milk proteins, particularly casein, into solid curds and liquid whey. This curdling process aids in the digestion of milk proteins by slowing down the passage of milk through the stomach, thus allowing more time for digestion and nutrient absorption. In addition to aiding digestion, rennin also plays a role in protecting the delicate stomach lining from the harmful effects of acidic gastric juices.

67
Q

The hepatic portal vein is a major blood vessel in the body that carries nutrient-rich blood from the digestive organs to the liver. Here are some of its key characteristics:

A

Location: The hepatic portal vein originates from the junction of several veins, including the superior mesenteric vein and the splenic vein. It carries blood from organs such as the stomach, intestines, pancreas, and spleen to the liver.
Function: The primary function of the hepatic portal vein is to transport absorbed nutrients from the digestive system to the liver for processing and storage. These nutrients include glucose, amino acids, vitamins, and minerals.
Blood Composition: The blood in the hepatic portal vein is rich in nutrients absorbed from the digestive tract, as well as metabolic by-products and toxins that need to be detoxified by the liver.
Portal System: The hepatic portal vein is part of the portal venous system, which is a unique system of veins that carry blood from one organ to another before returning it to the heart. In this case, the blood passes through the liver before eventually returning to the heart via the hepatic veins.
Branches: The hepatic portal vein branches within the liver, forming a network of smaller blood vessels called sinusoids. These sinusoids allow the liver to process nutrients, remove toxins, and perform other metabolic functions.
Overall, the hepatic portal vein plays a crucial role in nutrient absorption, detoxification, and metabolic regulation within the body.

68
Q

The specialized cells that control the opening and closing of stomata pores are called

A

The specialized cells that control the opening and closing of stomata pores are called guard cells. These cells are found in the epidermis of plant leaves and stems, surrounding each stomatal pore. Guard cells play a crucial role in regulating gas exchange, including the intake of carbon dioxide (CO2) for photosynthesis and the release of oxygen (O2) and water vapor.

When guard cells take up water, they become turgid and swell, causing them to curve outward and create an opening between them known as the stomatal pore. This allows for the exchange of gases between the plant and the surrounding environment. Conversely, when guard cells lose water, they become flaccid and shrink, causing the stomatal pore to close.

The opening and closing of stomata are primarily regulated by changes in the turgor pressure within the guard cells. This pressure is controlled by the movement of ions and water across the cell membranes of the guard cells, which is influenced by various environmental factors such as light intensity, temperature, humidity, and the plant’s water status.

Guard cells respond to signals such as light and the plant hormone abscisic acid (ABA) to adjust the aperture of the stomatal pore accordingly. This regulation helps plants optimize photosynthesis while minimizing water loss through transpiration.

69
Q

The blood vessel that carries digested food from the small intestine to the liver is called the

A

The blood vessel that carries digested food from the small intestine to the liver is called the hepatic portal vein. After absorption in the small intestine, nutrients and other substances are transported through the hepatic portal vein to the liver for processing and storage.

The hepatic portal vein is responsible for carrying blood rich in absorbed nutrients, such as glucose, amino acids, vitamins, and minerals, from the small intestine to the liver. In the liver, these nutrients are metabolized, stored, or distributed to other parts of the body as needed.

This specialized circulatory pathway allows the liver to regulate the levels of nutrients in the bloodstream and ensures that absorbed substances from the digestive tract are properly processed before being released into the general circulation.

70
Q

Renal Vein:

A

Renal Vein:
The renal vein carries deoxygenated blood from the kidneys back to the heart.
It removes waste products and excess substances, such as urea, from the bloodstream for excretion in the urine.
The renal vein also helps regulate blood pressure by controlling the volume of blood in the body.

71
Q

Renal Artery:

A

The renal artery carries oxygenated blood from the heart to the kidneys.
It delivers nutrients and oxygen to the kidney tissues to support their metabolic functions.
The renal artery also helps regulate blood pressure by delivering blood to the kidneys, which play a role in blood pressure regulation through the renin-angiotensin-aldosterone system.

72
Q

Hepatic Artery

A

Hepatic Artery:
The hepatic artery supplies oxygenated blood to the liver.
It provides nutrients and oxygen to liver cells to support their metabolic activities, including the processing and detoxification of substances absorbed from the digestive tract.
The hepatic artery also delivers glucose and other essential substances to the liver for storage and distribution throughout the body.

73
Q

Coeliac Artery (Celiac Artery):

A

Coeliac Artery (Celiac Artery):
The coeliac artery is a major branch of the abdominal aorta that supplies blood to several abdominal organs, including the stomach, liver, pancreas, and spleen.
It delivers oxygenated blood to these organs to support their metabolic functions and maintain their health.
The coeliac artery also plays a crucial role in digestive processes by providing the necessary nutrients and oxygen to the digestive organs involved in food processing and nutrient absorption.

74
Q

Why is maize grain regarded as a fruit and not a seed

A

Maize grain is often regarded as a fruit rather than a seed because it develops from the ovary of the maize flower, making it a product of the plant’s reproductive structures. In botanical terms, fruits typically develop from the fertilized ovary of a flower and contain seeds.

Here’s why maize grain is considered a fruit:

Botanical Definition: In botanical terms, a fruit is the mature ovary of a flowering plant, usually containing seeds. In maize, each kernel develops from a separate ovary of the flower, making it a fruit by botanical definition.
Structure: Maize grains, also known as kernels, develop from the ovary of the maize flower after pollination and fertilization. Each kernel contains an embryo (the future plant) surrounded by a starchy endosperm and protected by a tough outer layer called the pericarp. This structure is characteristic of a fruit.
Seed Dispersal: Fruits play a crucial role in seed dispersal. In the case of maize, the mature kernels are dispersed when the cob dries and eventually releases the kernels, allowing them to fall to the ground and potentially germinate to grow new maize plants.

75
Q

Fruit and seed are both important structures in the life cycle of plants, but they serve different functions and exhibit distinct characteristics:

A

Definition:
Fruit: A fruit is the mature ovary of a flowering plant, usually containing seeds. It develops from the fertilized ovary after pollination and serves to protect and disperse the seeds.
Seed: A seed is the mature fertilized ovule of a flowering plant. It contains the embryonic plant, stored nutrients, and a protective seed coat.
Origin:
Fruit: Fruits develop from the ovary of the flower after pollination and fertilization.
Seed: Seeds develop from the ovule within the ovary of the flower after fertilization.
Structure:
Fruit: Fruits typically consist of three main parts: the exocarp (outer skin), the mesocarp (fleshy middle layer), and the endocarp (inner layer surrounding the seeds). They may contain one or more seeds.
Seed: Seeds consist of an embryo (the future plant), stored nutrients (endosperm or cotyledons), and a protective seed coat (testa).
Function:
Fruit: The primary function of a fruit is to protect and aid in the dispersal of seeds. Fruits often have attractive colors and flavors to entice animals to consume them, thus aiding in seed dispersal.
Seed: The primary function of a seed is to ensure the survival and dispersal of the plant species. Seeds contain the embryonic plant and stored nutrients necessary for germination and early growth.
Dispersal:
Fruit: Fruits aid in seed dispersal by attracting animals that consume the fruit and subsequently disperse the seeds through their droppings or by spitting out seeds.
Seed: Seeds may be dispersed by various mechanisms, including wind, water, animals, and mechanical forces.

76
Q

The biological conditions that lead to the formation of identical twins include:

A

Identical twins, also known as monozygotic twins, are produced when a single fertilized egg (zygote) splits into two separate embryos early in development. This splitting typically occurs within the first two weeks after fertilization. As a result, identical twins share the same genetic material and are essentially genetically identical.

The biological conditions that lead to the formation of identical twins include:

Monozygotic Splitting: This occurs when the zygote, formed by the union of a sperm and an egg during fertilization, undergoes a spontaneous splitting into two separate embryos. Each embryo then develops into a separate individual.
Early Embryo Development: The splitting of the zygote into two embryos must occur very early in development, usually within the first two weeks after fertilization. The earlier the splitting occurs, the more likely it is that the twins will develop separate amniotic sacs and placentas.
Genetic Identity: Identical twins result from the splitting of a single fertilized egg, so they share the same genetic material. They have identical DNA sequences and are usually of the same sex.
Chance Occurrence: The occurrence of identical twins is largely due to chance and does not run in families. It is estimated that identical twins account for about one-third of all twins born worldwide.
In contrast, fraternal twins (dizygotic twins) result from the fertilization of two separate eggs by two separate sperm cells and share, on average, 50% of their genetic material, like siblings born at different times. Fraternal twins are more common than identical twins and can run in families.

77
Q

Maize is considered a fruit because

A

The testa and fruit wall fuse after fertilization In botanical terms, maize (corn) is considered a fruit because the ovary wall, which becomes the pericarp or fruit wall, develops and encloses the seeds (kernels) after fertilization. The seeds themselves are the result of fertilization, and they are enclosed by the pericarp, which forms the outer covering of the corn cob. This characteristic of the ovary wall fusing with the seed coat or testa after fertilization is a defining feature of fruits in botanical classification.

78
Q

the structure of fruits

A

the structure of fruits:

Epicarp: The outermost layer of the pericarp, which is the outer covering of the fruit. It is often referred to as the skin or peel of the fruit.
Endocarp: The innermost layer of the pericarp, which directly surrounds the seeds.
Mesocarp: The middle layer of the pericarp, located between the epicarp and the endocarp. It is often the fleshy or fibrous part of the fruit.
Seed: The mature ovule of a flowering plant, containing the embryonic plant and stored nutrients, enclosed by the seed coat.
Pericarp: The entire wall of the fruit, consisting of three layers: epicarp, mesocarp, and endocarp. It surrounds and protects the seeds.

79
Q

Drupe

A

A drupe, also known as a stone fruit, is a type of fruit characterized by having a fleshy outer layer (exocarp and mesocarp) surrounding a hard, stone-like pit or seed (endocarp). The outer layer is often edible and juicy, while the inner seed is hard and protected. Examples of drupes include peaches, plums, cherries, and apricots.

80
Q

An achene

A

An achene is a type of simple dry fruit that contains a single seed and is indehiscent, meaning it does not split open to release the seed when mature. The seed is attached to the inner wall of the fruit at one point, while the rest of the fruit remains intact.

Achenes are typically small, dry, and hard, with a thin outer layer called the pericarp. They are commonly found in members of the sunflower family (Asteraceae), such as sunflowers, dandelions, and thistles. In some cases, achenes may have structures like wings or hairs that aid in dispersal by wind, water, or animals.

One example of an achene is the sunflower seed, where the edible part is the seed itself, and the hard outer covering is the achene.

81
Q

An achene

A

An achene is a type of simple dry fruit that contains a single seed and is indehiscent, meaning it does not split open to release the seed when mature. The seed is attached to the inner wall of the fruit at one point, while the rest of the fruit remains intact.

Achenes are typically small, dry, and hard, with a thin outer layer called the pericarp. They are commonly found in members of the sunflower family (Asteraceae), such as sunflowers, dandelions, and thistles. In some cases, achenes may have structures like wings or hairs that aid in dispersal by wind, water, or animals.

One example of an achene is the sunflower seed, where the edible part is the seed itself, and the hard outer covering is the achene.

82
Q

Samara

A

Samara refers to a type of winged seed or fruit in plants, typically found in trees. It is characterized by a papery or wing-like structure attached to the seed, which aids in dispersal by wind. The samara’s wing-like structure allows it to catch the wind and travel away from the parent plant, helping the plant to spread its seeds over a wider area.

Common examples of trees that produce samaras include maples, ashes, elms, and birches. The shape and size of samaras can vary depending on the species of tree. In some cases, samaras may have a single wing, while in others, they may have two wings.

Samaras are often referred to as “helicopter seeds” due to their spinning motion as they fall from the tree, resembling the descent of a helicopter rotor. This spinning motion helps the samara to travel further away from the parent tree, increasing the chances of successful seed dispersal and colonization of new areas.

83
Q

Caryopsis

A

A caryopsis is a type of dry, one-seeded fruit that is characteristic of the grass family (Poaceae), which includes cereal grains such as wheat, rice, barley, and corn (maize). It is also commonly referred to as a grain.

The caryopsis fruit has several distinctive features:

Seed Coat Fusion: In caryopsis, the seed coat is firmly fused with the ovary wall (pericarp), making it difficult to separate the seed from the fruit wall. This fusion helps protect the seed during development and dispersal.
Single Seed: Each caryopsis contains a single seed, which is the mature ovule of the plant.
Endosperm: The endosperm, which is a nutrient-rich tissue that provides nourishment to the developing embryo, is also an integral part of the caryopsis.
Hard, Dry Pericarp: The pericarp of a caryopsis is thin and dry at maturity. It does not split open to release the seed, as seen in other types of fruits.
Caryopses are important food sources for humans and animals alike. They are rich in carbohydrates, proteins, vitamins, and minerals, making them staple foods in many cultures around the world. Additionally, caryopses are adapted for dispersal by various means, including wind, water, and animals.

84
Q

Contractile vacoule

A

The contractile vacuole is a structure found in certain single-celled organisms, including amoebas and some protists, that live in freshwater environments. Its primary function is to regulate osmotic pressure by expelling excess water from the cell to maintain internal balance.

In environments with lower solute concentration than the cell’s cytoplasm, water tends to move into the cell by osmosis, causing it to swell. The contractile vacuole actively collects and pumps out this excess water, preventing the cell from bursting due to osmotic pressure.

The contractile vacuole works through a cycle of filling with water and then contracting to expel it through a pore in the cell membrane. This process helps these organisms survive in freshwater habitats where osmotic pressure changes frequently.

85
Q

Number of feeders decreases as you go down the food chain

A

Here’s why:

Energy Loss: At each trophic level, energy is lost as heat during metabolic processes. This means that the higher-level consumers have less energy available to them compared to the producers at the base of the food chain.
Biomass Pyramid: The biomass (total mass of living organisms) at each trophic level forms a pyramid, with the greatest biomass at the producer level (plants and algae) and successively smaller biomass as you move up through the consumers. This indicates that there are fewer individuals at higher trophic levels.
Energy Efficiency: Only a fraction of the energy consumed by one organism is passed on to the next trophic level. As a result, there is less energy available to support larger populations at higher trophic levels.

86
Q

Insects have various mechanisms to conserve water, especially in arid environments or during periods of water scarcity. Here are some ways insects conserve water:

A

Cuticle: The outer layer of an insect’s exoskeleton, called the cuticle, is covered with a waxy layer that helps prevent water loss through evaporation. This waterproofing layer reduces the permeability of the cuticle, helping to retain moisture inside the insect’s body.
Reduced Surface Area: Some insects have evolved adaptations to reduce their surface area, minimizing the area through which water can be lost. For example, many desert insects have a compact body shape with reduced appendages to minimize surface exposure.
Behavioral Adaptations: Insects may exhibit behavioral adaptations to avoid water loss. For example, many insects are nocturnal, becoming active during cooler, more humid hours when water loss is reduced. Some insects also seek shelter in microhabitats that offer higher humidity levels, such as under rocks or in leaf litter.
Respiratory System: Insects have a highly efficient respiratory system that helps minimize water loss. Their tracheal system delivers oxygen directly to tissues without the need for a transport medium like blood, reducing the loss of water through respiration.
Feeding Strategies: Some insects obtain water directly from their food sources, reducing their dependence on external water sources. Succulent plants, nectar, and fruits can serve as water sources for many insects.
Metabolic Adaptations: Insects have metabolic adaptations that allow them to conserve water internally. They produce concentrated urine and feces to minimize water loss, and some insects can enter a state of dormancy or aestivation during dry periods to conserve water.
Water Storage: Certain insects have specialized structures for storing water. For example, desert-dwelling beetles have specialized storage organs in their body that allow them to retain water for long periods.

87
Q

Root hairs have their origin from ?

A

Root hairs originate from the epidermal cells of the root. These specialized cells elongate and differentiate to form long, slender projections known as root hairs. Root hairs play a crucial role in the absorption of water and nutrients from the soil, as they significantly increase the surface area available for absorption.

88
Q

Magnesium utilized in formation of atp?

A

Yes, magnesium is indeed utilized in the formation of ATP (adenosine triphosphate). Magnesium serves as a cofactor for the enzyme ATP synthase, which is responsible for the final step in ATP synthesis during cellular respiration. In this step, ATP synthase uses energy derived from the proton gradient across the inner mitochondrial membrane to catalyze the conversion of ADP (adenosine diphosphate) and inorganic phosphate (Pi) into ATP. Magnesium helps stabilize the ATP synthase complex and is required for its proper function in ATP production. Therefore, magnesium is essential for ATP synthesis, which is the primary energy currency of cells.

89
Q

Geotropism, also known as gravitropism, is the growth response of plants to gravity. It influences the direction of growth of roots and stems in relation to the gravitational field. Here’s how geotropism affects roots and stems differently:

A

Geotropism in Roots:

Positive Geotropism: Roots exhibit positive geotropism, meaning they grow in the direction of gravity. In other words, roots grow downward into the soil.
Root Tips: The tips of roots, known as root caps, contain specialized cells called statocytes that sense gravity. When the statocytes detect the gravitational pull, they trigger hormonal changes that promote downward root growth.
Function: Positive geotropism in roots helps anchor the plant securely in the soil and facilitates the absorption of water and nutrients from deeper soil layers.
Geotropism in Stems:

Negative Geotropism: Stems typically exhibit negative geotropism, meaning they grow against the direction of gravity (upward).
Stem Tips: Similar to roots, stem tips contain statocytes that detect gravity. However, in stems, the response to gravity is opposite to that of roots.
Function: Negative geotropism in stems enables the plant to grow upward toward sources of light and away from the soil surface, where competition for light is intense. This upward growth optimizes photosynthesis and enhances the plant’s ability to compete for sunlight with neighboring plants.
Overall, the different responses of roots and stems to gravity contribute to the plant’s ability to optimize its growth and adapt to its environment. Roots grow downward to anchor the plant and access water and nutrients, while stems grow upward toward light to maximize photosynthesis and reproductive success.

90
Q
A
91
Q

Respiration

A

i) Respiration in plants is different from that of animals as plants do not have any special system for gaseous exchange.

(ii) Stomata and lenticels allow gaseous exchange by diffusion.

(iii) Respiration is a process in living organisms involving the production of energy, typically with the intake of oxygen and the release of carbon dioxide from the oxidation of complex organic substances.

(iv) Glucose is the favoured substrate for respiration but fats and proteins can also be broken down to yield energy.

92
Q

Types of respiration:

A

(i) Respiration can be aerobic or anaerobic.

(ii) In both types, the initial phase occurs in cytoplasm and it is called glycolysis.

(iii) Each glucose molecule is broken through a series of enzyme catalysed reactions into two molecules of pyruvic acid by a process called glycolysis.

(iv) The fate of the pyruvate depends on the availability of oxygen and the organism.

93
Q

Anaerobic respiration:

A

(i) Under anaerobic conditions, either lactic acid fermentation or alcohol fermentation occurs.

(ii) Fermentation takes place under anaerobic conditions in many prokaryotes, unicellular eukaryotes and in germinating seeds.

94
Q

Aerobic respiration:

A

i) Under aerobic conditions, in eukaryotic organisms, the pyruvic acid is transported into mitochondria where it is converted to acetyl Co-A through oxidative decarboxylation.

(ii) Acetyl Co-A is the link between glycolysis and Krebs cycle (TCA cycle).

(iii) The electrons move through energy carriers and release energy at various points to synthesise ATP by a process called oxidative phosphorylation.

(iv) In oxidative phosphorylation,
O
2
is the ultimate acceptor of electrons and it gets reduced to water.

(v) The respiratory pathway is an amphibolic pathway as it involves both anabolism and catabolism.

(vi) The total net gain of ATP in aerobic respiration in eukaryotes is
36

ATP
while in prokaryotes it is
38

ATP
.

(vii) The ratio of the volume of
CO
2
evolved to the volume of
O
2
consumed in respiration is called Respiratory Quotient (RQ).