Biology 11

Question 1

Which subclass of plants show secondary growth

Answer 1

The subclass of plants that typically exhibit secondary growth is the class Magnoliopsida, also known as dicots. These plants have a vascular cambium layer that allows for secondary growth, resulting in the thickening of stems and roots over time. This secondary growth enables dicots to increase in girth and develop woody tissues, contributing to their structural support and longevity. In contrast, plants in the class Liliopsida, or monocots, typically lack secondary growth and do not form woody tissues.

Question 2

Fungi are considered a distinct group of eukaryotes due to several distinguishing characteristics:

Answer 2

Cell Wall Composition: Fungi have cell walls primarily composed of chitin, a structural polysaccharide, whereas the cell walls of plants are composed mainly of cellulose.Mode of Nutrition: Fungi are heterotrophic organisms, meaning they obtain their nutrients by absorbing organic matter from their environment. They do this through extracellular digestion, secreting enzymes to break down complex organic compounds externally before absorbing the resulting smaller molecules. In contrast, plants are autotrophic, producing their own food through photosynthesis.Absence of Chlorophyll: Unlike plants, fungi lack chlorophyll and are unable to perform photosynthesis. Therefore, they rely on organic matter as a source of carbon and energy.Reproduction: Fungi reproduce both sexually and asexually, often through the production of spores. Their reproductive structures, such as mushrooms or mold spores, are distinct from those of plants.Morphology: Fungi exhibit a wide range of morphological diversity, including unicellular yeast, filamentous molds, and multicellular mushrooms. This diversity sets them apart from plants and other eukaryotic organisms.Overall, these differences in cell structure, nutritional mode, reproductive strategies, and morphology contribute to fungi being recognized as a distinct group within the eukaryotic domain.

Question 3

Radial Symmetry:

Answer 3

In radial symmetry, body parts are arranged around a central axis, similar to spokes on a wheel. This type of symmetry is commonly found in organisms that are sessile or free-floating in aquatic environments, such as jellyfish, sea anemones, and some types of sea stars.

Question 4

Bilateral Symmetry:

Answer 4

Bilateral symmetry is characterized by a body plan that can be divided into two equal halves along a single plane, resulting in mirror-image halves. This type of symmetry is prevalent in animals that exhibit cephalization, where sensory organs and nervous tissues are concentrated at the anterior end of the body. Examples include vertebrates (such as mammals, birds, and fish), arthropods (such as insects and crustaceans), and mollusks (such as snails and clams).

Question 5

Asymmetry

Answer 5

: Asymmetry refers to the absence of any plane of symmetry, resulting in an irregular or uneven body shape. While most animals exhibit some degree of symmetry, certain organisms, such as sponges, exhibit asymmetrical body plans.

Question 6

Birds share several features with reptiles, indicating their evolutionary relationship. Some of these features include:

Answer 6

Scales: Both birds and reptiles have scales covering their skin. In birds, scales are most noticeable on their legs and feet, while reptiles typically have scales covering their entire body.Amniotic Eggs: Both birds and reptiles lay amniotic eggs, which have protective membranes that prevent desiccation and provide a stable environment for the developing embryo. This adaptation allowed both groups to colonize terrestrial habitats successfully.Feathers and Scales: Feathers, the defining characteristic of birds, are believed to have evolved from scales. The structure of feathers shares similarities with reptilian scales, suggesting a common ancestry.Endothermy: While reptiles are primarily ectothermic (relying on external sources of heat to regulate body temperature), birds exhibit endothermy (the ability to regulate body temperature internally). However, some reptiles, such as certain species of snakes and crocodiles, exhibit behaviors that allow them to regulate body temperature, resembling the thermoregulatory mechanisms observed in birds.Skeletal Features: Birds and reptiles share similarities in their skeletal structure, including the presence of a single middle ear bone (the columella), as well as certain cranial and vertebral characteristics.These shared features provide evidence of the evolutionary relationship between birds and reptiles, with birds being considered descendants of certain groups of ancient reptiles, particularly theropod dinosaurs.

Question 7

Plant macronutrient

Answer 7

Macronutrients are needed in relatively large quantities and include elements like nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S).

Question 8

Plant micronutrient

Answer 8

Micronutrients, also known as trace elements, are needed in smaller quantities and include elements like iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B), molybdenum (Mo), and chlorine (Cl).

Question 9

Sundew

Answer 9

Actually, sundews are not parasitic. They are carnivorous plants that obtain nutrients by trapping and digesting small insects or other arthropods. They are considered autotrophs because they still perform photosynthesis to produce their own food using sunlight, water, and carbon dioxide. Sundews have specialized leaves covered with glandular hairs that secrete sticky substances to trap prey. Once an insect is caught, the sundew releases enzymes to digest it and absorb the nutrients. This unique adaptation allows sundews to thrive in nutrient-poor environments where they supplement their diet with insects.

Question 10

Loranthus

Answer 10

Loranthus, commonly known as mistletoe, is a genus of parasitic plants that belong to the family Loranthaceae. These plants are known for their distinctive growth habit of attaching themselves to the branches of trees and shrubs. Loranthus extracts water and nutrients from their host plants, relying on them for support and sustenance. They have small, green leaves and produce clusters of flowers, often with bright colors, which attract pollinators. Mistletoe has cultural significance in various traditions and is sometimes used in holiday decorations, especially during the Christmas season.

Question 11

Hydrochloric acid (HCl) in the human stomach serves several functions:

Answer 11

1. Acidic Environment: HCl creates an acidic environment in the stomach, with a pH of around 2, which is essential for the activation of digestive enzymes and the breakdown of food particles.
   
   2. Activation of Pepsinogen: HCl activates the enzyme pepsinogen, converting it into its active form, pepsin. Pepsin is crucial for breaking down proteins into smaller peptides during the process of digestion.
   3. Killing Pathogens: The acidic environment of the stomach, maintained by HCl, helps in killing ingested bacteria and other pathogens, reducing the risk of infections from contaminated food and water.
   4. Denaturation of Proteins: HCl helps in the denaturation of dietary proteins, unfolding them and making them more accessible to digestive enzymes for breakdown.

Overall, HCl plays a critical role in the digestive process by creating an optimal environment for the action of digestive enzymes and ensuring effective digestion of food.

Question 12

hydrochloric acid (HCl) in the stomach can stop the action of

Answer 12

hydrochloric acid (HCl) in the stomach can stop the action of ptyalin, also known as salivary amylase. Ptyalin is an enzyme produced in the salivary glands that helps break down starches into smaller sugars like maltose.

When food enters the stomach, the acidic environment created by HCl can denature ptyalin, reducing its activity. This is one reason why the digestion of starches primarily occurs in the mouth and not in the stomach. Once food leaves the stomach and enters the small intestine, where the pH is less acidic, the action of ptyalin can resume.

Question 13

Ultrafiltration in the kidney primarily occurs in

Answer 13

Ultrafiltration in the kidney primarily occurs in the renal corpuscles, specifically in the glomerular capillaries within the Bowman’s capsule. The glomerular capillaries are specialized to allow small molecules like water, ions, and waste products to pass through their walls under pressure, while retaining larger molecules like proteins and blood cells. This process results in the formation of the glomerular filtrate, which contains water, ions, glucose, amino acids, and waste products such as urea and creatinine.

Question 14

Secondary thickening in plants is primarily mediated by

Answer 14

Secondary thickening in plants is primarily mediated by the activity of two meristems: the vascular cambium and the cork cambium. The vascular cambium produces secondary xylem (wood) towards the interior and secondary phloem towards the exterior, contributing to the increase in girth or diameter of the stem or root. The cork cambium, also known as the phellogen, produces cork cells towards the exterior, providing protection and contributing to bark formation.

Question 15

Orange

Answer 15

An orange is an example of a fruit that develops from a single carpel. It belongs to the category of fruits known as simple fruits, specifically a type called a hesperidium. In an orange, the ovary of a single carpel matures into the fruit containing the seeds, surrounded by a fleshy, leathery rind.

Question 16

Okra

Answer 16

Okra (okro) - Okra is a vegetable that develops from the ovary of a single carpel, but it is not typically classified as a fruit.

Question 17

Tomato

Answer 17

• The tomato is also a fruit that develops from the ovary of a single carpel. It is a type of berry known as a “true berry.”

Question 18

Beans

Answer 18

Bean - Beans are seeds that develop within pods, but they are not typically considered fruits that develop from a single carpel. Instead, they are legumes.

Question 19

Giberrellin

Answer 19

Gibberellin: Gibberellins are a class of plant hormones that regulate various aspects of plant growth and development, including stem elongation, seed germination, and flowering. They are involved in promoting cell division and elongation, particularly in the stem, and are crucial for the growth of stems and leaves.

Question 20

Kinetin

Answer 20

Kinetin: Kinetin is a synthetic cytokinin, a type of plant hormone that regulates cell division and differentiation. It is commonly used in plant tissue culture to promote cell division and shoot formation.

Question 21

Abscisic Acid:

Answer 21

Abscisic acid (ABA) is a plant hormone that plays a role in seed dormancy, drought tolerance, and stress responses. It inhibits germination and regulates stomatal closure to prevent water loss during drought conditions.

Question 22

Ethylene

Answer 22

: Ethylene is a gaseous plant hormone involved in various physiological processes, including fruit ripening, senescence, and response to stress. It regulates fruit ripening by promoting the conversion of starches to sugars and the degradation of cell walls, leading to softening and color changes in fruits.

Question 23

Ans

Answer 23

The autonomic nervous system regulates involuntary bodily functions, such as heart rate, digestion, respiratory rate, and glandular activity. It consists of two main branches: the sympathetic nervous system, which activates the body’s fight-or-flight response in stressful situations, and the parasympathetic nervous system, which promotes relaxation and restores the body to a state of rest. In this context, the neurons in the autonomic nervous system control the heart rate (option B) among other functions.

Question 24

Plants of temperate origin can be grown in tropical areas in the vegetation zones of the D. montane forest.
Explain

Answer 24

Plants of temperate origin can be grown in tropical areas within the montane forest vegetation zone because the montane forest has cooler temperatures and higher elevations, resembling the conditions found in temperate regions. This allows plants adapted to temperate climates to thrive in these areas despite the surrounding tropical environment.

Question 25

Abiotic factors that control human population include:

Answer 25

1. Climate: Extreme temperatures, precipitation levels, and other climatic factors can affect human settlement patterns and agricultural productivity.
   
   2. Water availability: Access to clean water is essential for human survival and influences where populations can establish settlements.
   3. Soil fertility: The quality of soil affects agricultural productivity and food availability, which can impact population growth and distribution.
   4. Topography: The physical features of the land, such as mountains, rivers, and coastlines, can influence human settlement patterns and accessibility to resources.
   5. Natural disasters: Events like earthquakes, hurricanes, floods, and droughts can disrupt human populations, causing displacement, loss of life, and damage to infrastructure.
   6. Pollution: Contamination of air, water, and soil can negatively impact human health and well-being, affecting population growth and distribution.
   7. Altitude: High-altitude regions may have lower population densities due to harsher environmental conditions and limited access to resources.

Question 26

Discontinuous variation in plants

Answer 26

refers to traits or characteristics that show distinct, non-overlapping differences among individuals within a population. This type of variation typically results from the influence of one or a few genes and can often be observed as distinct categories or phenotypes. Examples include flower color in peas (where flowers are either purple or white) or seed shape in corn (where seeds are either round or wrinkled).

Question 27

Continuous variation

Answer 27

in plants refers to the variation in traits that can take on a range of intermediate values within a population. These traits are controlled by multiple genes and are influenced by environmental factors. Examples include plant height, leaf size, and seed weight. Continuous variation results in a bell-shaped distribution curve when plotted, with most individuals clustered around the average value and fewer individuals at the extremes.

Question 28

Blood Group A:

Answer 28

Individuals with blood group A have A antigens on the surface of their red blood cells and anti-B antibodies in their plasma. They can receive blood from individuals with blood groups A and O, and can donate blood to individuals with blood groups A and AB.

Question 29

Blood Group B:

Answer 29

Individuals with blood group B have B antigens on the surface of their red blood cells and anti-A antibodies in their plasma. They can receive blood from individuals with blood groups B and O, and can donate blood to individuals with blood groups B and AB.

Question 30

Blood Group AB

Answer 30

: Individuals with blood group AB have both A and B antigens on the surface of their red blood cells and no anti-A or anti-B antibodies in their plasma. They are universal recipients, meaning they can receive blood from individuals with any blood group (A, B, AB, or O), but can only donate blood to individuals with blood group AB.

Question 31

Blood Group O:

Answer 31

Individuals with blood group O have no A or B antigens on the surface of their red blood cells but have both anti-A and anti-B antibodies in their plasma. They are universal donors, meaning they can donate blood to individuals with any blood group (A, B, AB, or O), but can only receive blood from individuals with blood group O.

Question 32

Cassava height

Answer 32

Cassava height is typically considered as a continuous variation. Continuous variation refers to traits that can take on any value within a range, rather than being limited to distinct categories. In the case of cassava height, it can vary along a continuum, with some plants being shorter and others taller, and various heights in between. This variation can be influenced by genetic factors, environmental conditions, and interactions between genes and the environment.

Question 33

Colour blind

Answer 33

When a color-blind man marries a carrier woman, the probability of their offspring being color blind depends on the inheritance pattern of the condition. Color blindness is typically inherited as a recessive trait carried on the X chromosome. If the man is color blind (XY) and the woman is a carrier (XcX), their offspring would have the following probabilities:
• Sons have a 50% chance of being color blind (XY) and a 50% chance of not being color blind (XYc).
• Daughters have a 50% chance of being carriers (XcX) and a 50% chance of not being carriers (XX).

Question 34

The correct base pairing for DNA is

Answer 34

A. adenine 2 thymine and guanine 2 cytosine.

Question 35

Introspecific competition

Answer 35

, also known as intraspecific competition, occurs when individuals of the same species compete for limited resources within their shared environment. This form of competition can involve various resources such as food, water, shelter, mates, or territory.

In introspecific competition, individuals of the same species may directly compete with one another for access to resources, which can lead to a variety of interactions including aggression, territorial disputes, or mating competitions. The intensity of introspecific competition can vary depending on factors such as population density, resource availability, and environmental conditions.

Overall, introspecific competition plays a significant role in shaping population dynamics, regulating population size, and influencing the distribution and behavior of individuals within a species.

Question 36

Paramecium aurelia and Paramecium caudatum

Answer 36

are two species of ciliated protozoans belonging to the genus Paramecium. While they share many similarities, they also have some notable differences:

1.	Size: Paramecium aurelia is generally smaller in size compared to Paramecium caudatum.
2.	Shape: Paramecium aurelia typically has a more elongated or oval shape, while Paramecium caudatum tends to be more rounded.
3.	Contractile vacuole: The contractile vacuole, responsible for osmoregulation, is more prominent in Paramecium caudatum compared to Paramecium aurelia.
4.	Locomotion: Paramecium aurelia moves in a spiral or helical path, while Paramecium caudatum moves in a more linear manner.
5.	Habitat: Paramecium aurelia is often found in freshwater habitats such as ponds and lakes, while Paramecium caudatum can also inhabit brackish water environments.
6.	Reproduction: Both species reproduce asexually by binary fission, but Paramecium aurelia may also engage in sexual reproduction under certain conditions.

These are just a few of the differences between Paramecium aurelia and Paramecium caudatum, and there may be other distinctions in their behavior, physiology, and ecology.

Question 37

A. P. aurelia is better adapted for obtaining food than P. caudatum.

Answer 37

This means that in the given context or environment, P. aurelia has traits or adaptations that make it more efficient at acquiring food resources compared to P. caudatum. These adaptations could include factors such as feeding strategies, morphology, or physiological traits that give P. aurelia an advantage in obtaining food.

Question 38

Basking in the sun for agama lizards is an adaptation for

Answer 38

thermoregulation. Agama lizards, like many reptiles, are ectothermic, meaning they rely on external sources of heat to regulate their body temperature. Basking in the sun allows them to absorb solar radiation, which raises their body temperature and helps them maintain optimal metabolic function. By adjusting their position and orientation relative to the sun, agama lizards can effectively regulate their body temperature, ensuring they remain active and able to perform essential physiological functions such as digestion, locomotion, and reproduction.

Question 39

Flesh-Tearing Birds (e.g., Raptors):

Answer 39

Raptors have strong, hooked beaks designed for tearing flesh. These beaks are sharp and curved at the tip, allowing them to grasp and tear apart prey efficiently. They also have a sharp cutting edge on the upper mandible, known as the tomial tooth, which aids in slicing through meat.

Question 40

Mud-Straining Birds (e.g., Flamingos):

Answer 40

Birds like flamingos have uniquely shaped beaks adapted for filter-feeding. Their beaks are long, thin, and curved downward, resembling a sieve or strainer. They use these specialized beaks to sweep through shallow water, trapping small organisms like plankton and algae while expelling excess water. This adaptation allows them to efficiently extract food from muddy or sandy substrates.

Question 41

Seed-Eating Birds (e.g., Finches):

Answer 41

These birds have short, stout beaks that are adapted for cracking open seeds and nuts. The beaks are often conical or thickened to exert force.

Question 42

Insect-Eating Birds (e.g., Woodpeckers):

Answer 42

Birds that primarily feed on insects have sharp, pointed beaks that allow them to pick insects out of tree bark or crevices. Woodpeckers have long, chisel-shaped beaks for drilling into wood to access insects.

Question 43

Nectar-Feeding Birds (e.g., Hummingbirds):

Answer 43

Birds that feed on nectar have long, slender, and often curved beaks that are specialized for reaching deep into flowers. These beaks allow them to extract nectar efficiently.

Question 44

Fish-Eating Birds (e.g., Herons):

Answer 44

Birds that hunt fish typically have long, sharp, spear-like beaks that they use to catch and grasp fish in water. These beaks are often pointed and have a strong, curved shape.

Question 45

Gene flow and genetic drift

Answer 45

Gene flow refers to the transfer of genetic material from one population to another through migration or interbreeding, which can lead to genetic variation within and between populations.Genetic drift, on the other hand, refers to the random fluctuations in allele frequencies in a population due to chance events. This can occur more prominently in smaller populations and can lead to the loss of genetic diversity over time.

Question 46

Gene flow and genetic drift

Answer 46

Gene flow refers to the transfer of genetic material from one population to another through migration or interbreeding, which can lead to genetic variation within and between populations.Genetic drift, on the other hand, refers to the random fluctuations in allele frequencies in a population due to chance events. This can occur more prominently in smaller populations and can lead to the loss of genetic diversity over time.

Question 47

Gene flow and genetic drift

Answer 47

Gene flow refers to the transfer of genetic material from one population to another through migration or interbreeding, which can lead to genetic variation within and between populations.Genetic drift, on the other hand, refers to the random fluctuations in allele frequencies in a population due to chance events. This can occur more prominently in smaller populations and can lead to the loss of genetic diversity over time.

Question 48

Comparative anatomy

Answer 48

Darwin derived his theory of evolution from his observations of the different species of finches on the Galapagos Islands. He noticed variations in their beak shapes and sizes that seemed to correlate with the type of food available on each island. This observation led him to propose that species could change over time through a process of natural selection, where individuals with advantageous traits are more likely to survive and reproduce, passing on those traits to their offspring. This process ultimately results in the adaptation of species to their environments and the emergence of new species over time. Darwin’s study of the finches’ anatomy provided crucial evidence supporting his theory of evolution by natural selection.

Question 49

The clitellum of earthworms

Answer 49

The clitellum of earthworms is responsible for secreting the cocoon that encloses the eggs during reproduction. It also produces mucus to aid in sperm transfer during mating. Additionally, it plays a role in nutrient absorption and respiration.