Biology 8

Question 1

Thallophytes

Answer 1

Thallophytes are a group of non-vascular plants that lack specialized tissues for transporting water and nutrients. They include algae, fungi, and some types of bacteria. Thallophytes are characterized by their simple body structure, which is not differentiated into roots, stems, and leaves.

Question 2

Liverworts and mosses are classified as

Answer 2

Liverworts and mosses are classified as bryophytes. Bryophytes are non-vascular plants that typically grow in moist environments. They lack true roots, stems, and leaves and reproduce via spores. Liverworts and mosses are both examples of early land plants and play important roles in ecosystems as soil stabilizers and habitat providers.

Question 3

Yeast reproduces through two main methods:

Answer 3

Asexual Reproduction: Yeast primarily reproduces asexually through a process called budding. In budding, a small outgrowth called a bud forms on the parent yeast cell. This bud grows in size until it eventually detaches from the parent cell, becoming a new yeast cell.
Sexual Reproduction: Yeast can also undergo sexual reproduction under certain conditions. This involves the fusion of two yeast cells to form a diploid cell, which then undergoes meiosis to produce haploid spores. These spores can germinate into new yeast cells under favorable conditions.

Question 4

Binary Fission:

Answer 4

Binary fission is a method of asexual reproduction in which a single organism divides into two daughter organisms, each with identical genetic material.
It is commonly observed in bacteria, where the genetic material replicates, and the cell divides into two daughter cells.
Example: Escherichia coli (E. coli) bacteria reproduce by binary fission.

Question 5

Multiple Fission:

Answer 5

Multiple fission is a type of asexual reproduction in which a single parent organism divides into multiple daughter organisms simultaneously.
This process typically involves the formation of multiple daughter cells within the parent organism, which are then released simultaneously.
Example: Some species of protozoa, such as Plasmodium spp., undergo multiple fission during their life cycle.

Question 6

Fragmentation

Answer 6

:
Fragmentation is a form of asexual reproduction in which an organism breaks into fragments, and each fragment grows into a new individual.
It is commonly observed in certain types of algae, fungi, and some plants.
Example: Spirogyra, a filamentous green algae, reproduces through fragmentation, where a filament breaks into fragments, each capable of developing into a new filament.

Question 7

Budding:

Answer 7

Budding is a process of asexual reproduction in which a new organism develops as an outgrowth or bud on the parent organism.
The bud grows in size until it detaches from the parent, becoming a separate individual.
Budding is observed in various organisms, including yeast, Hydra, and some types of sponges.
Example: Yeast cells reproduce through budding, where a small bud forms on the parent cell and eventually separates to become a new yeast cell.

Question 8

Flame cells,

Answer 8

Flame cells, also known as protonephridia, are specialized excretory structures found in flatworms, such as planarians. These cells play a crucial role in osmoregulation and waste removal in these organisms.

Key features of flame cells include:

Structure: Flame cells are flask-shaped cells that line the internal tubules of the protonephridial system. Each flame cell consists of a tuft of cilia (resembling a flame) that projects into the lumen of the tubule.
Function: The cilia of flame cells beat rhythmically, creating a current that draws fluid from the interstitial fluid into the tubules. This fluid contains metabolic wastes, excess water, and ions.
Filtration: As the fluid flows through the tubules, it passes through specialized cells with microvilli that aid in filtration. These cells selectively reabsorb valuable ions and nutrients while allowing waste products to remain in the tubules.
Excretion: The filtered fluid, now concentrated with waste products, exits the body through specialized pores located on the surface of the organism. These pores are connected to the protonephridial tubules and allow for the expulsion of waste fluid from the body.
Overall, flame cells are essential for maintaining the internal environment of flatworms by regulating water and ion balance and removing metabolic wastes. They represent a primitive excretory system that allows these organisms to survive in their aquatic or moist habitats.

Question 9

Bloodworms

Answer 9

Bloodworms are the larvae of certain species of midges in the family Chironomidae. These segmented worms are commonly found in aquatic habitats, especially in freshwater environments such as ponds, lakes, and streams. They are known for their bright red coloration, which is due to the presence of hemoglobin in their bodies.

Key points about bloodworms include:

Habitat: Bloodworms inhabit the bottom sediments of freshwater bodies, where they burrow into the mud or detritus. They are often found in areas with low oxygen levels, as they possess adaptations that allow them to survive in hypoxic conditions.
Anatomy: Bloodworms have elongated, cylindrical bodies divided into distinct segments. They typically range in size from a few millimeters to several centimeters in length. Their characteristic red coloration comes from hemoglobin, which helps them transport oxygen in low-oxygen environments.
Feeding: Bloodworms are detritivores and filter feeders, meaning they primarily consume organic matter and microorganisms present in the sediment. They use their specialized feeding appendages to collect and ingest food particles from the surrounding substrate.
Life cycle: Bloodworms undergo complete metamorphosis, starting as eggs laid in aquatic environments. The larvae hatch from the eggs and spend several weeks to months developing in the water before pupating. The pupal stage eventually gives rise to adult midges, which emerge from the water to mate and lay eggs, completing the life cycle.
Economic importance: Bloodworms are commercially harvested and sold as bait for fishing. Anglers use them as effective bait for attracting a variety of freshwater fish species, including trout, bass, and panfish.
Overall, bloodworms play a significant role in freshwater ecosystems as decomposers and as an essential food source for aquatic organisms. Additionally, their use as bait contributes to recreational fishing activities around the world.

Question 10

Discontinuous variation

Answer 10

Discontinuous variation refers to traits that exhibit distinct categories with no intermediate forms between them. Examples of traits that demonstrate discontinuous variation include:

Blood type: Blood type is determined by specific antigens present on the surface of red blood cells. There are four main blood types: A, B, AB, and O. Each blood type represents a distinct category with no intermediate forms.
Tongue rolling: The ability to roll the tongue into a tube shape is a classic example of discontinuous variation. Some individuals can roll their tongues, while others cannot, with no intermediate forms between the two categories.
Hitchhiker’s thumb: The ability of the thumb to bend backward at a sharp angle when extended is another example of discontinuous variation. Some people exhibit this trait (known as a hitchhiker’s thumb), while others do not, with no gradual variation between the two categories.
Earlobe attachment: Earlobe attachment refers to whether the earlobe is attached directly to the side of the head (attached earlobe) or hangs freely (unattached earlobe). This trait demonstrates discontinuous variation, as individuals typically fall into one of the two distinct categories.
Presence of dimples: Dimples are small indentations that appear on the cheeks when smiling. Some individuals have dimples, while others do not, with no intermediate forms between the two categories.
These examples illustrate how certain traits exhibit clear-cut categories with no variation in between, demonstrating discontinuous variation in populations.

Question 11

One biological advantage of inbreeding is

Answer 11

One biological advantage of inbreeding is that it can help in the fixation of desirable traits within a population.

Question 12

All blood groups can have both homozygous and heterozygous forms.

Answer 12

All blood groups can have both homozygous and heterozygous forms. The ABO blood group system, for example, consists of four blood types: A, B, AB, and O. Each blood type can be present in both homozygous (having two identical alleles) and heterozygous (having two different alleles) forms.

Question 13

Vitamin B1 (Thiamine):

Answer 13

Function: Helps the body convert carbohydrates into energy and is essential for proper nerve function.
Deficiency: Can lead to beriberi, characterized by fatigue, weakness, nerve damage, and heart problems.

Question 14

Vitamin B2 (Riboflavin):

Answer 14

Vitamin B2 (Riboflavin):
Function: Plays a crucial role in energy production, metabolism of fats, drugs, and steroids, and helps maintain healthy skin and eyes.
Deficiency: May cause ariboflavinosis, resulting in sore throat, redness, and swelling of the lining of the mouth and throat, cracks or sores on the outsides of the lips, and inflammation and redness of the tongue.

Question 15

Vitamin B3 (Niacin):

Answer 15

Function: Essential for energy metabolism, DNA repair, and cell signaling. It also helps lower cholesterol levels.
Deficiency: Can lead to pellagra, which is characterized by diarrhea, dermatitis, dementia, and, if left untreated, death.

Question 16

Vitamin B5 (Pantothenic Acid):

Answer 16

Function: Plays a key role in the synthesis of coenzyme A (CoA), which is involved in numerous metabolic pathways, including the production of energy.
Deficiency: Rare, but symptoms may include fatigue, irritability, numbness, and tingling in the hands and feet.

Question 17

Vitamin B6 (Pyridoxine):

Answer 17

Function: Important for brain development and function, the production of neurotransmitters, and the metabolism of amino acids and carbohydrates.
Deficiency: Can lead to anemia, neurological symptoms, dermatitis, and a weakened immune response.

Question 18

Vitamin B7 (Biotin):

Answer 18

Function: Essential for the metabolism of carbohydrates, fats, and proteins. It also plays a role in gene expression and cell signaling.
Deficiency: Rare, but may cause hair loss, skin rashes, neurological symptoms, and metabolic disturbances.

Question 19

Vitamin B9 (Folate):

Answer 19

Function: Vital for DNA synthesis, cell division, and the formation of red blood cells.
Deficiency: Can result in megaloblastic anemia, birth defects, neurological disorders, and an increased risk of heart disease.

Question 20

Vitamin B12 (Cobalamin):

Answer 20

Function: Necessary for the formation of red blood cells, neurological function, DNA synthesis, and energy production.
Deficiency: Can lead to pernicious anemia, neurological damage, fatigue, weakness, and mood disturbances.

Question 21

The theory of use and disuse, proposed by

Answer 21

The theory of use and disuse, proposed by Jean-Baptiste Lamarck in the early 19th century, suggests that organisms can develop new characteristics or lose existing ones based on how they use or don’t use certain body parts. According to this theory:

Use: Lamarck proposed that organs or body parts that are used frequently become stronger and more developed over time. For example, if an animal uses its muscles extensively, those muscles will become larger and more robust.
Disuse: Conversely, Lamarck suggested that organs or body parts that are not used gradually weaken and may eventually disappear. For instance, if an animal stops using a particular limb, that limb may become smaller or less functional over successive generations.
Lamarck believed that these acquired characteristics could be passed on to offspring, leading to evolutionary change within a species. However, this theory has been largely discredited in modern biology due to the lack of evidence supporting the inheritance of acquired traits. Instead, the modern understanding of evolution is based on the principles of natural selection, genetic mutation, and genetic drift.

Question 22

Glycerol is a byproduct of the digestion of

Answer 22

Glycerol is a byproduct of the digestion of triglycerides, which are a type of lipid or fat. During digestion, triglycerides are broken down into fatty acids and glycerol by enzymes called lipases. This process usually occurs in the small intestine with the help of bile acids secreted by the liver. Once broken down, the fatty acids and glycerol are absorbed by the intestinal cells and then transported through the bloodstream to various tissues where they can be used for energy or stored for later use.

Question 23

The soil type with the highest capillary action is

Answer 23

The soil type with the highest capillary action is typically clay soil. Clay particles are very small and have a high surface area, allowing them to hold water more effectively than larger particles like sand or silt. This high water retention capacity in clay soil enables it to exhibit strong capillary action, drawing water upward against gravity through small spaces between soil particles. As a result, clay soil tends to retain moisture well and can provide a steady supply of water to plants even during dry periods.

Question 24

Polio

Answer 24

Caused by the poliovirus, which primarily affects the nervous system.
Can lead to paralysis, muscle weakness, and in severe cases, death.
Prevented by vaccination, which has greatly reduced its incidence worldwide.
Transmission occurs through contact with infected feces or respiratory secretions.

Question 25

Gonorrhea

Answer 25

Gonorrhea:
A sexually transmitted infection caused by the bacterium Neisseria gonorrhoeae.
Common symptoms include pain during urination and abnormal discharge from the genitals.
If left untreated, gonorrhea can lead to serious complications such as pelvic inflammatory disease and infertility.
Treatment usually involves antibiotics, although drug-resistant strains are a growing concern.

Question 26

Syphilis

Answer 26

:
Caused by the bacterium Treponema pallidum, which is primarily transmitted through sexual contact.
Progresses through stages, including primary, secondary, latent, and tertiary syphilis.
Symptoms vary depending on the stage but can include painless sores, rash, fever, and neurological problems.
Early detection and treatment with antibiotics are crucial to prevent severe complications.

Question 27

Cholera

Answer 27

An acute diarrheal illness caused by the bacterium Vibrio cholerae.
Spread through contaminated water and food, particularly in areas with poor sanitation.
Symptoms include severe diarrhea, vomiting, and dehydration, which can lead to death if untreated.
Treatment involves rehydration therapy and antibiotics in severe cases.

Question 28

Typhoid:

Answer 28

Caused by the bacterium Salmonella typhi, primarily transmitted through contaminated food and water.
Symptoms include sustained fever, headache, abdominal pain, and rash.
Typhoid fever can lead to serious complications such as intestinal perforation and bloodstream infection.
Prevention involves good sanitation practices, vaccination in high-risk areas, and proper food and water hygiene.

Question 29

Removing petals from a flower can have several potential effects, including:

Answer 29

Reduced attractiveness: Petals are often brightly colored and play a crucial role in attracting pollinators like bees, butterflies, and birds. Removing petals may make the flower less attractive to these pollinators, reducing its chances of successful pollination and reproduction.
Decreased reproductive success: Petals help protect the reproductive organs of the flower, including the stamens (male reproductive organs) and pistil (female reproductive organ). Without petals, these delicate structures may be more vulnerable to damage or desiccation, leading to reduced reproductive success.
Impact on seed production: Successful pollination and fertilization are essential for seed production in flowering plants. Removing petals may interfere with this process, resulting in reduced seed production or even sterility in the flower.
Aesthetic changes: Petals contribute to the overall appearance and beauty of a flower. Removing petals can alter the aesthetic appeal of the flower, potentially making it less visually appealing.
In summary, while removing petals from a flower may not necessarily harm the plant directly, it can have negative consequences for its reproductive success, attractiveness to pollinators, and overall aesthetic appeal.

Question 30

Carbon dating

Answer 30

Carbon dating is a method used by archaeologists and scientists to determine the age of organic materials such as wood, bone, cloth, and plant fibers. It relies on the principle of radioactive decay, specifically the decay of carbon-14 isotopes in the material.

Carbon-14 is a radioactive isotope of carbon that is naturally present in the atmosphere. Living organisms absorb carbon-14 from the atmosphere through photosynthesis or by consuming other organisms. When an organism dies, it stops taking in carbon-14, and the amount of carbon-14 in its tissues begins to decrease over time as it undergoes radioactive decay.

By measuring the remaining amount of carbon-14 in a sample and comparing it to the initial amount present in the atmosphere, scientists can estimate the age of the sample. This process is known as radiocarbon dating or carbon dating.

Carbon dating is particularly useful for dating organic materials that are between 100 and 50,000 years old. It has revolutionized the field of archaeology by providing a reliable method for dating ancient artifacts, fossils, and other organic remains. However, carbon dating has limitations, such as the need for organic material and the potential for contamination, which scientists must consider when interpreting results.

Question 31

Honey queens

Answer 31

Queens: Queens are the reproductive females of the colony. Their primary role is to lay eggs, producing the next generation of worker bees and drones. Queens are larger than workers and have a distinct elongated abdomen. They are fed a special diet called royal jelly during their larval stage, which enables them to develop fully functioning reproductive organs. Once mature, a queen will mate with drones outside the hive and return to lay eggs within the colony.

Question 32

Honey workers

Answer 32

Workers: Workers are sterile female bees responsible for most of the tasks within the hive. These tasks include tending to the queen, feeding and caring for the larvae, foraging for nectar and pollen, building and repairing comb, and defending the hive. Workers transition through different roles as they age, starting with cleaning cells and feeding larvae, then progressing to tasks such as guarding the entrance, producing wax, and finally foraging outside the hive. The majority of bees in a colony are workers.

Question 33

Honey drones

Answer 33

Drones: Drones are the male bees in the colony. Their primary role is to mate with queens from other colonies. Drones do not have stingers and are larger and stockier than workers, with large eyes to aid in locating queens during mating flights. Drones are reared during times of high colony population and are expelled from the hive during periods of food scarcity or before winter. Only a few drones are present in a hive at any given time.

Question 34

In terms of defending the hive

Answer 34

In terms of defending the hive, workers are primarily responsible for this task. They patrol the hive entrance and will attack intruders or predators to protect the colony. Workers may sting intruders as a form of defense, sacrificing their lives in the process. Drones do not participate in defending the hive, as they are focused on mating and do not possess stingers. Queens also do not engage in hive defense, as their primary role is reproduction.

Question 35

Soil pH and rainfall

Answer 35

Soil pH and rainfall primarily affect terrestrial ecosystems rather than aquatic ones. However, changes in soil pH can indirectly impact aquatic ecosystems through processes like runoff and leaching. When soil pH levels are altered, it can affect the chemistry of water bodies through runoff, which can carry sediment and dissolved substances into streams, rivers, and lakes.

Similarly, rainfall can influence aquatic ecosystems by affecting the flow of water, nutrient levels, and habitat availability. Heavy rainfall can lead to increased runoff, which can wash pollutants, sediment, and nutrients into aquatic environments, potentially causing water quality issues and altering aquatic habitats.

Overall, while soil pH and rainfall may not directly affect aquatic animals, their influence on water quality and habitat conditions can have significant indirect effects on aquatic ecosystems and the organisms that inhabit them.

Question 36

Intermediate host of schistosoma

Answer 36

Snail

Question 37

A species niche

Answer 37

A species niche refers to the specific role or position that a species occupies within its ecosystem. It encompasses the various interactions, behaviors, and ecological relationships that a species has with its environment, including its habitat, resources, and interactions with other species.

Question 38

Key aspects of a species niche include:

Answer 38

Habitat: The physical environment where the species lives and carries out its activities.
Food and resources: The specific types of food, shelter, and resources that the species relies on for survival and reproduction.
Behavior: The behaviors and activities that the species engages in to obtain resources, reproduce, and interact with other organisms.
Interactions: The relationships and interactions that the species has with other species, including competition, predation, mutualism, and symbiosis.
Tolerance limits: The range of environmental conditions, such as temperature, humidity, and pH, within which the species can survive and function.

Question 39

Population density is

Answer 39

total population/total area

Question 40

The opening of guard cells in the epidermis is facilitated by the process of

Answer 40

The opening of guard cells in the epidermis is facilitated by the process of osmosis.

Question 41

Allelle. Genotype and phenotype

Answer 41

Alleles are different forms of a gene that occupy the same position (locus) on a chromosome.
Genotype refers to the genetic makeup of an organism, which includes all the alleles present in its genome.
Phenotype is the observable traits or characteristics of an organism, which result from the interaction between its genotype and the environment.
Alleles determine the variations in phenotypic traits among individuals of the same species.
An individual’s genotype influences its phenotype by determining which alleles are present and how they interact with each other.
Environmental factors can also influence phenotype by modifying the expression of genes.
Alleles can be dominant or recessive, where dominant alleles are expressed in the phenotype even if only one copy is present, while recessive alleles are expressed only when two copies are present.
Genotype-phenotype relationships are complex and can involve multiple genes interacting with each other and with the environment to produce observable traits.

Question 42

appendicular skeleton

Answer 42

The appendicular skeleton is one of the two main divisions of the human skeleton, the other being the axial skeleton.
It consists of the bones of the limbs (arms and legs) and their associated girdles (shoulder and pelvic girdles).
The appendicular skeleton provides support and mobility to the body, allowing for movement and manipulation of objects.
The shoulder girdle, or pectoral girdle, consists of the clavicle (collarbone) and scapula (shoulder blade) bones, which attach the upper limbs to the axial skeleton.
The pelvic girdle consists of the hip bones (coxal bones), sacrum, and coccyx, which attach the lower limbs to the axial skeleton.
The upper limb includes the humerus (upper arm bone), radius and ulna (forearm bones), carpals (wrist bones), metacarpals (palm bones), and phalanges (finger bones).
The lower limb includes the femur (thigh bone), patella (kneecap), tibia and fibula (lower leg bones), tarsals (ankle bones), metatarsals (foot bones), and phalanges (toe bones).
The appendicular skeleton provides attachment points for muscles and ligaments, allowing for movement and stability during activities such as walking, running, and lifting.

Question 43

Black flies,

Answer 43

Black flies, also known as buffalo gnats or turkey gnats, belong to the family Simuliidae and are small, dark-colored flies.
They are found worldwide, particularly in humid, fast-flowing freshwater habitats such as rivers and streams.
Black flies are known for their painful bites, which can cause irritation, swelling, and itching in humans and animals.
Only the females bite, as they require a blood meal for egg development. The males feed on nectar and other plant juices.
Black flies are vectors for various pathogens and parasites, including filarial worms and protozoa, which they can transmit to humans and animals through their bites.
Some species of black flies are also responsible for transmitting diseases such as onchocerciasis (river blindness) and Mansonellosis (Manson’s eye worm) in humans.
Larvae of black flies are aquatic and typically attach themselves to submerged rocks or vegetation in fast-flowing water, where they feed on organic matter and algae.
Control measures for black flies include the use of larvicides to target larvae in aquatic habitats, insect repellents to deter biting adults, and protective clothing to prevent bites.

Question 44

biosphere

Answer 44

The biosphere refers to the global sum of all ecosystems on Earth, including the living organisms (plants, animals, and microorganisms) and their interactions with the non-living components of the environment (such as air, water, and soil). It encompasses the entire surface of the Earth and extends from the highest points of the atmosphere to the deepest parts of the oceans.

Question 45

Key points about the biosphere include:

Answer 45

Interconnectedness: The biosphere is characterized by the complex interactions and interconnectedness of living organisms with each other and with their physical environment.
Biodiversity: It encompasses a vast array of species, ranging from microscopic bacteria to large mammals, and includes diverse habitats such as forests, grasslands, deserts, and aquatic ecosystems.
Ecological Processes: Within the biosphere, various ecological processes such as nutrient cycling, energy flow, and the regulation of climate and atmospheric composition occur, which are essential for maintaining life on Earth.
Human Impact: Human activities, such as deforestation, pollution, and climate change, have significant impacts on the biosphere, leading to habitat destruction, loss of biodiversity, and disruptions to ecological processes.
Sustainability: Ensuring the long-term health and sustainability of the biosphere requires conservation efforts, sustainable resource management, and global cooperation to address environmental challenges.