Biology 14

Question 1

Nitrogen fixation and thunderstorms

Answer 1

Certainly! Thunderstorms can contribute to the enrichment of soil through a process called atmospheric nitrogen fixation. Here’s how it works:Atmospheric Nitrogen: The Earth’s atmosphere is composed mainly of nitrogen gas (N2), which makes up about 78% of the air we breathe.Nitrogen Fixation: Lightning, which occurs during thunderstorms, has enough energy to split nitrogen molecules in the air (N2) into individual nitrogen atoms (N). This process is called nitrogen fixation.Formation of Nitrogen Oxides: The individual nitrogen atoms (N) produced by lightning quickly combine with oxygen molecules (O2) in the atmosphere to form nitrogen oxides (NOx), such as nitrogen dioxide (NO2) and nitric oxide (NO).Dissolving in Rainwater: Nitrogen oxides are water-soluble and dissolve in rainwater, forming nitric acid (HNO3) and nitrous acid (HNO2).Nitrate Formation: Nitric acid and nitrous acid react with water and other substances in the atmosphere to form nitrates (NO3-), which are soluble in water.Nutrient Delivery: When it rains, the nitrogen-containing compounds, including nitrates, are carried down to the soil by rainfall. These nitrates serve as a source of nitrogen, an essential nutrient for plant growth.Soil Enrichment: Once in the soil, nitrates are readily absorbed by plant roots and utilized for various metabolic processes, including protein synthesis and growth. This enrichment of the soil with nitrogen helps to support plant growth and contributes to the overall fertility of the soil.Overall, thunderstorms play a crucial role in the natural nitrogen cycle by converting atmospheric nitrogen into a form that can be utilized by plants, thereby contributing to soil fertility and ecosystem productivity.

Question 2

Heating soil up

Answer 2

The experiment you described is likely aimed at determining the organic matter content in the soil. When soil is heated, organic matter such as dead plant material, microbes, and other organic substances will burn off at different temperatures.

Heating till Red Hot: This step burns off any organic matter present in the soil, leaving behind inorganic materials such as minerals and ash.

Further Heating till No Smoke: Once the organic matter has burned off, further heating ensures that all volatile organic compounds have been driven off, leaving behind only the inorganic components.

By measuring the weight loss of the soil sample before and after heating, scientists can calculate the percentage of organic matter in the soil. This information is important for understanding soil fertility, nutrient cycling, and overall soil health.

Question 3

Anopheles mosquito

Answer 3

Key points about Anopheles mosquito metamorphosis include:

1.	Complete Metamorphosis: Like other mosquito species, Anopheles mosquitoes undergo complete metamorphosis, consisting of four stages: egg, larva, pupa, and adult.
2.	Egg Stage: Female Anopheles mosquitoes lay eggs individually on the surface of freshwater bodies, typically in areas with still or slow-moving water.
3.	Larval Stage: Anopheles mosquito larvae hatch from the eggs and live in water, feeding on organic matter and microorganisms. They have a distinct head and abdomen, with specialized structures for breathing underwater, including a siphon.
4.	Pupal Stage: Larvae molt into pupae, which are comma-shaped and non-feeding. During this stage, they undergo dramatic physiological changes, preparing for emergence as adults.
5.	Adult Stage: After several days as pupae, adult Anopheles mosquitoes emerge from the water. They rest on nearby vegetation until their exoskeleton hardens, then fly away to find mates and feed on nectar or blood.
6.	Disease Transmission: Anopheles mosquitoes are vectors for malaria, a potentially deadly disease caused by Plasmodium parasites. Female Anopheles mosquitoes require a blood meal to develop their eggs, and during feeding, they can transmit the malaria parasite to humans.
7.	Control Strategies: Understanding the life cycle of Anopheles mosquitoes is crucial for implementing effective control measures to reduce mosquito populations and prevent malaria transmission. This includes methods such as habitat modification, insecticide application, and the use of mosquito nets and repellents to protect against bites.

Question 4

blue cobalt chloride paper

Answer 4

, can also be used to detect water loss from a leaf. Cobalt chloride paper is blue when hydrated and turns pink when it loses water, making it a useful indicator of moisture levels. By placing the blue cobalt chloride paper under a leaf, the paper will turn pink as it absorbs water lost through transpiration. This color change can be visually observed and quantified to measure the rate of water loss from the leaf.

Question 5

Yam plant storage

Answer 5

In a yam plant, carbohydrates are primarily stored in the stem, particularly in the form of starch. The tubers, which are swollen underground stems, serve as the main storage organs for carbohydrates. Therefore, the correct answer is “stem.”

Question 6

Common plants that store food in their buds include:

Answer 6

1. Onion (Allium cepa): Onions store nutrients in their bulb, which is a modified underground bud consisting of layers of modified leaves.
   
   2. Garlic (Allium sativum): Similar to onions, garlic stores nutrients in its bulb, which is also a modified underground bud composed of layers of modified leaves.
   3. Potato (Solanum tuberosum): Potatoes store nutrients in their underground tubers, which are essentially enlarged underground stems or buds. These tubers serve as a storage organ for carbohydrates.
   4. Ginger (Zingiber officinale): Ginger stores nutrients in its rhizomes, which are underground stems or modified buds. These rhizomes contain starches and other nutrients.
   5. Lily (Lilium spp.): Lilies store nutrients in their bulbs, which are underground storage organs formed from modified buds. These bulbs contain stored carbohydrates and other nutrients to support the growth of the plant.

These are just a few examples of common plants that store food in their buds.

Question 7

Common plants that store food in their adventitious roots include:

Answer 7

1. Sweet Potato (Ipomoea batatas): Sweet potatoes store nutrients in their enlarged, fleshy adventitious roots, which are often referred to as tuberous roots. These roots contain stored carbohydrates, particularly starches, which serve as an energy reserve for the plant.
   
   2. Carrot (Daucus carota): Carrots store nutrients in their taproots, which are thickened, fleshy roots that store sugars and other carbohydrates. These roots serve as an energy reserve for the plant.
   3. Beetroot (Beta vulgaris): Beetroot stores nutrients in its swollen taproot, which is rich in sugars, particularly sucrose. This taproot serves as a storage organ for carbohydrates.
   4. Radish (Raphanus sativus): Radishes store nutrients in their enlarged, fleshy taproots, which contain carbohydrates, including sugars and starches. These taproots serve as an energy reserve for the plant.
   5. Turnip (Brassica rapa subsp. rapa): Turnips store nutrients in their enlarged, fleshy taproots, which contain carbohydrates, primarily starches. These taproots serve as an energy reserve for the plant.

Question 8

Common plants that store food in their leaves include:

Answer 8

1. Aloe Vera (Aloe barbadensis): Aloe vera stores water and nutrients in its thick, fleshy leaves. These leaves contain a gel-like substance rich in carbohydrates, particularly polysaccharides, which serve as an energy reserve for the plant.
   
   2. Succulents (e.g., Jade Plant, Snake Plant): Many succulent plants store water and nutrients in their thick, fleshy leaves. These leaves are adapted to store moisture and often contain carbohydrates and other nutrients that serve as energy reserves.
   3. Cacti (e.g., Prickly Pear, Saguaro): Cacti store water and nutrients in their succulent stems and leaves. The fleshy pads or segments of cacti contain stored carbohydrates, particularly sugars and starches, which serve as energy reserves.
   4. Agave (Agave spp.): Agave plants store carbohydrates, primarily in the form of fructans, in their thick, fleshy leaves. These carbohydrates serve as an energy reserve for the plant and are harvested to produce agave syrup.
   5. Ornamental Plants (e.g., Bromeliads, Kalanchoe): Some ornamental plants store water and nutrients in their leaves. For example, bromeliads store water in their central rosette of leaves, while kalanchoe plants store water and nutrients in their fleshy leaves.

Question 9

Several plants have the ability to propagate from leaves, either through natural processes or by human intervention. Here are some common examples:

Answer 9

1. African Violet (Saintpaulia spp.): African violets can be propagated from leaf cuttings. A healthy leaf with a short stem is cut from the parent plant and placed in a moist growing medium. Adventitious roots develop from the leaf’s base, and a new plantlet forms at the leaf’s edge.
   
   2. Jade Plant (Crassula ovata): Jade plants can be propagated from leaf or stem cuttings. Leaves or stem segments are allowed to callus for a few days before being placed in well-draining soil. Roots and new shoots develop from the callused areas, leading to the growth of new plants.
   3. Snake Plant (Sansevieria spp.): Snake plants can be propagated from leaf cuttings. Leaves are cut into sections, and each section is planted in soil. New shoots and roots emerge from the cut ends of the leaf sections, giving rise to new plants.
   4. Succulents (Various genera): Many succulent plants, including various types of Echeveria, Sedum, and Kalanchoe, can be propagated from individual leaves. Leaves are carefully removed from the parent plant and laid on top of well-draining soil. Roots and new rosettes or plantlets develop from the base of the leaf, eventually forming new plants.
   5. Begonia (Various species): Some begonia species can be propagated from leaf cuttings. Healthy leaves are cut from the parent plant and placed on top of moist soil or in a tray of water. Adventitious roots and new shoots develop from the leaf’s base, leading to the formation of new plants.

Question 10

Grasshoppers

Answer 10

: Grasshoppers undergo incomplete metamorphosis, which means they have three stages: egg, nymph, and adult. The nymphs look like smaller versions of the adults but lack wings. As they grow, they molt several times, gradually developing wings and sexual organs until they reach adulthood.

Question 11

Bees

Answer 11

: Bees undergo complete metamorphosis, which consists of four stages: egg, larva, pupa, and adult. The egg hatches into a larva, which is fed by worker bees. The larva then undergoes pupation, during which it transforms into an adult bee inside a cocoon-like structure called a cell. The adult bee emerges from the cell and undergoes further development before becoming sexually mature.

Question 12

Termites

Answer 12

: Termites also undergo incomplete metamorphosis. They have three stages: egg, nymph, and adult. The nymphs resemble smaller versions of the adults but lack fully developed reproductive organs. As they mature, they molt and gradually develop wings and reproductive capabilities.

Question 13

The liver regulates blood sugar through several mechanisms:

Answer 13

1. Glycogen Storage and Release: The liver stores excess glucose in the form of glycogen when blood sugar levels are high, such as after a meal. When blood sugar levels drop, the liver breaks down glycogen into glucose and releases it into the bloodstream to maintain normal blood sugar levels.
   
   2. Gluconeogenesis: The liver can also produce glucose from non-carbohydrate sources, such as amino acids and glycerol, through a process called gluconeogenesis. This helps maintain blood glucose levels during fasting or periods of low carbohydrate intake.
   3. Glycogenolysis: In addition to releasing glucose from glycogen stores, the liver can also break down glycogen directly into glucose through a process called glycogenolysis. This provides a rapid source of glucose when needed, such as during exercise or periods of stress.
   4. Insulin and Glucagon Regulation: The liver responds to hormonal signals from insulin and glucagon to regulate blood sugar levels. Insulin promotes glucose uptake by cells and inhibits glycogen breakdown in the liver, while glucagon stimulates glycogen breakdown and glucose release from the liver when blood sugar levels are low.

Overall, the liver plays a central role in maintaining blood sugar homeostasis by balancing glucose production and utilization in response to dietary intake, hormonal signals, and metabolic demands.

Question 14

Liver stores iron

Answer 14

Yes, the liver stores iron. One of the liver’s functions is to regulate the levels of iron in the body. It stores excess iron absorbed from the diet and releases it when needed. Iron is an essential mineral that plays a crucial role in various bodily functions, including oxygen transport, energy production, and DNA synthesis. The liver helps maintain iron balance by storing excess iron in a form called ferritin and releasing it into the bloodstream as needed. However, excessive accumulation of iron in the liver can lead to conditions such as hemochromatosis, a disorder characterized by iron overload.

Question 15

Liver regulate blood sugar

Answer 15

Yes, the liver plays a crucial role in regulating blood sugar levels. It helps maintain blood glucose within a narrow range, which is essential for providing energy to the body’s cells and ensuring overall metabolic balance.The liver regulates blood sugar through several mechanisms:Glycogen Storage and Release: The liver stores excess glucose in the form of glycogen when blood sugar levels are high, such as after a meal. When blood sugar levels drop, the liver breaks down glycogen into glucose and releases it into the bloodstream to maintain normal blood sugar levels.Gluconeogenesis: The liver can also produce glucose from non-carbohydrate sources, such as amino acids and glycerol, through a process called gluconeogenesis. This helps maintain blood glucose levels during fasting or periods of low carbohydrate intake.Glycogenolysis: In addition to releasing glucose from glycogen stores, the liver can also break down glycogen directly into glucose through a process called glycogenolysis. This provides a rapid source of glucose when needed, such as during exercise or periods of stress.Insulin and Glucagon Regulation: The liver responds to hormonal signals from insulin and glucagon to regulate blood sugar levels. Insulin promotes glucose uptake by cells and inhibits glycogen breakdown in the liver, while glucagon stimulates glycogen breakdown and glucose release from the liver when blood sugar levels are low.Overall, the liver plays a central role in maintaining blood sugar homeostasis by balancing glucose production and utilization in response to dietary intake, hormonal signals, and metabolic demands.

Question 16

Budding:

Answer 16

• Yeast: Yeast is a single-celled fungus that reproduces asexually by budding. A small bud forms on the parent cell, grows in size, and eventually separates to become a new individual.
• Hydra: Hydra is a freshwater organism belonging to the phylum Cnidaria. It reproduces asexually by budding, where small buds develop on the body wall of the parent organism and eventually detach to form new individuals.

Question 17

Multiple Fission:

Answer 17

• Plasmodium: Plasmodium species are parasites that cause malaria in humans. During the asexual phase of their life cycle, Plasmodium undergoes multiple fission, where the nucleus divides multiple times within the cell before the cell divides into multiple daughter cells called merozoites.

Question 18

Budding and Binary Fission:

Answer 18

• Amoeba: Amoeba is a single-celled protist that can reproduce both sexually and asexually. It reproduces asexually by binary fission, where the cell divides into two daughter cells. Additionally, under certain conditions, amoeba can also reproduce by budding, where a smaller daughter cell forms as an outgrowth from the parent cell.

Question 19

Fragmentation

Answer 19

Fragmentation is a form of asexual reproduction in which an organism breaks into fragments, each of which develops into a new individual. This process is common in certain types of organisms, especially those with simple body structures or lacking specialized reproductive organs. Here are some examples:

1.	Fungi:
•	Rhizopus: Rhizopus is a genus of fungi commonly known as bread molds. They reproduce asexually through fragmentation, where hyphae (filamentous structures) break into fragments, each of which can grow into a new organism under suitable conditions.
2.	Algae:
•	Spirogyra: Spirogyra is a filamentous green algae that reproduces asexually by fragmentation. Portions of the filament break off and develop into new individuals, with each fragment capable of growing into a new filament under favorable environmental conditions.
3.	Plants:
•	Bryophytes: Some mosses and liverworts reproduce asexually by fragmentation. Portions of the parent plant break off and grow into new individuals when favorable conditions are present.
4.	Animals:
•	Planarians: Planarians are flatworms that can reproduce asexually by fragmentation. If a planarian is cut into pieces, each piece has the ability to regenerate into a complete individual, making fragmentation a form of reproduction in these organisms.
5.	Sponges:
•	Sponges (Porifera) can reproduce asexually through fragmentation. If a sponge is broken into pieces, each piece has the potential to develop into a new individual sponge through regeneration.

Question 20

Klinostat

Answer 20

: A klinostat is a device used in plant biology to study gravitropism, which is the response of plants to gravity. It consists of a rotating platform on which plants are placed. By rotating the platform at a constant speed, the klinostat prevents the plants from perceiving the direction of gravity, allowing researchers to study the effects of gravity on plant growth and development.

Question 21

Manometer

Answer 21

: A manometer is a device used to measure pressure, typically the pressure of gases or liquids. It consists of a U-shaped tube partially filled with a liquid (such as mercury or water). The difference in height between the two arms of the U-tube indicates the pressure difference between the two points being measured.

Question 22

Porometer:

Answer 22

A porometer is an instrument used to measure the rate of water loss or transpiration from the leaves of plants. It works by measuring the rate at which water vapor diffuses through small pores (stomata) on the surface of the leaf. Porometers are commonly used in plant physiology research to assess plant water stress and evaluate plant water use efficiency.

Question 23

Photometer

Answer 23

: A photometer is a device used to measure the intensity of light or other electromagnetic radiation. It typically consists of a sensor or detector that measures the amount of light reaching it. Photometers are used in various fields, including photography, astronomy, environmental monitoring, and optics, to quantify the brightness or intensity of light sources.

Question 24

The rate of transpiration of a leafy shoot is generally highest under the following conditions:

Answer 24

High Light Intensity: Transpiration rates increase with higher light intensity because photosynthesis, which occurs in the presence of light, drives the opening of stomata. This allows for greater water loss through transpiration.
2. High Temperature: Warmer temperatures increase the rate of evaporation of water from the leaf surface, leading to higher transpiration rates. This is because higher temperatures increase the vapor pressure deficit between the leaf and the surrounding air, promoting greater water loss.
3. Low Humidity: Transpiration rates are higher in drier air because the vapor pressure deficit between the leaf surface and the surrounding air is greater, facilitating faster water loss from the leaf.
4. High Air Movement (Wind): Increased air movement around the leaf, such as windy conditions, can enhance transpiration rates by removing the boundary layer of humid air surrounding the leaf, which slows down water vapor diffusion from the leaf surface.

Question 25

The two main types of human tapeworms are Taenia solium (pork tapeworm) and Taenia saginata (beef tapeworm). These tapeworms can be distinguished by several characteristics:

Answer 25

1. Host Species: Taenia solium primarily infects humans who consume undercooked pork contaminated with cysts containing the tapeworm larvae. Taenia saginata, on the other hand, primarily infects humans who consume undercooked beef contaminated with cysts containing the tapeworm larvae.
   
   2. Size and Shape: While both tapeworms have a long, ribbon-like body composed of multiple segments called proglottids, they can be distinguished by differences in size and shape. Taenia solium tends to be smaller, with adults typically measuring 2-7 meters in length, while Taenia saginata is larger, with adults often reaching lengths of 4-10 meters.
   3. Number of Hooks: Taenia solium has hooks on the scolex (the attachment organ at the front end of the tapeworm), which it uses to attach to the intestinal wall. These hooks are absent in Taenia saginata.
   4. Uterine Branching: In Taenia solium, the uterus has fewer branches compared to Taenia saginata. The proglottids of Taenia solium typically have a single uterine branch, while those of Taenia saginata have multiple branches

Question 26

Respiratory organ of crabs

Answer 26

Crabs and other crustaceans have gills as their respiratory organs. Gills are feathery structures located in the branchial chamber, which is typically located under the carapace (the hard upper shell) or on the sides of the crab’s body. Gills are responsible for extracting oxygen from water and releasing carbon dioxide, allowing the crab to breathe underwater.

Question 27

Normally, any characteristic shown by an organism is due to the effects of its genetic makeup (genotype), environmental factors, or a combination of both.

Answer 27

1. Genetic Makeup (Genotype): The genetic information encoded in an organism’s DNA determines its inherited traits and characteristics. Genes control various aspects of an organism’s physiology, morphology, behavior, and other traits. These genetic traits are passed down from parents to offspring through the process of reproduction.
   
   2. Environmental Factors: Environmental factors such as temperature, humidity, light, nutrient availability, and interactions with other organisms can also influence an organism’s phenotype (observable characteristics). Environmental conditions can affect gene expression, development, and behavior, leading to variations in phenotype even among individuals with the same genotype.
   3. Interaction between Genes and Environment: In many cases, an organism’s phenotype results from the interaction between its genotype and environmental factors. This concept is known as gene-environment interaction. Environmental conditions can influence how genes are expressed or activated, leading to phenotypic variation within a population.

Question 28

Factors that affect the growth of an organism

Answer 28

1. Genetic Makeup (Genotype): The genetic information encoded in an organism’s DNA determines its inherited traits and characteristics. Genes control various aspects of an organism’s physiology, morphology, behavior, and other traits. These genetic traits are passed down from parents to offspring through the process of reproduction.
   
   2. Environmental Factors: Environmental factors such as temperature, humidity, light, nutrient availability, and interactions with other organisms can also influence an organism’s phenotype (observable characteristics). Environmental conditions can affect gene expression, development, and behavior, leading to variations in phenotype even among individuals with the same genotype.
   3. Interaction between Genes and Environment: In many cases, an organism’s phenotype results from the interaction between its genotype and environmental factors. This concept is known as gene-environment interaction. Environmental conditions can influence how genes are expressed or activated, leading to phenotypic variation within a population.

Question 29

A dry dehiscent fruit

Answer 29

A dry dehiscent fruit is a type of fruit that dries out as it matures and eventually splits open (dehisces) to release its seeds. These fruits typically develop from a single carpel and split open along specific seams or sutures to release their seeds. Dry dehiscent fruits are further classified based on the manner in which they split open.One example of a dry dehiscent fruit is the pea pod, which is characteristic of plants in the pea family (Fabaceae). Pea pods develop from a single carpel and split open along two seams (sutures) to release the seeds (peas) contained within.Another example is the capsule, which is a type of dry dehiscent fruit found in various plant families. Capsules can have various shapes and sizes and may split open along multiple seams or pores to release their seeds.Dry dehiscent fruits are contrasted with dry indehiscent fruits, which do not split open at maturity. Instead, dry indehiscent fruits remain closed and typically rely on other mechanisms, such as wind or animal dispersal, to release their seeds. Examples of dry indehiscent fruits include achenes (e.g., sunflower seeds) and nuts (e.g., acorns).

Question 30

A simple fruit

Answer 30

A simple fruit is a type of fruit that develops from the ovary of a single flower and typically contains seeds from a single ovule or multiple ovules within a single carpel. Simple fruits are classified based on their structure and whether they are fleshy or dry at maturity.One example of a simple fruit is the tomato (Solanum lycopersicum). The tomato fruit develops from the ovary of a single flower and contains multiple seeds derived from multiple ovules within a single carpel. The outer fleshy portion of the tomato is derived from the ovary wall, while the seeds are embedded within the juicy pulp.Another example is the apple (Malus domestica). The apple fruit also develops from the ovary of a single flower, with the seeds originating from multiple ovules within a single carpel. The fleshy part of the apple is derived from the swollen ovary wall, known as the receptacle, while the seeds are located in the core of the fruit.Simple fruits can be further classified into two main categories based on their texture at maturity:Fleshy Fruits: Fleshy fruits have a soft, succulent texture at maturity and may contain high water content. Examples include tomatoes, apples, berries (such as strawberries and blueberries), and drupes (such as peaches and cherries).Dry Fruits: Dry fruits have a firm, dry texture at maturity and may split open (dehisce) or remain closed. Examples include nuts (such as acorns and hazelnuts), achenes (such as sunflower seeds), capsules (such as poppy seeds), and samaras (such as maple seeds).These examples illustrate the diversity of simple fruits and their importance in plant reproduction and seed dispersal.

Question 31

A fruit formed from a single flower having several free carpels is

Answer 31

A fruit formed from a single flower having several free carpels is called a multiple fruit. In a multiple fruit, each carpel develops into a separate fruit, and these individual fruits become fused together into a single, aggregate structure as they mature. Each fruit in a multiple fruit originates from a separate ovary within the same flower.One common example of a multiple fruit is the pineapple (Ananas comosus). The pineapple fruit develops from the fusion of the ovaries of multiple flowers, each with its own separate carpel. As the individual fruits mature, they merge together to form the larger pineapple fruit.Another example of a multiple fruit is the fig (Ficus carica). The fig fruit develops from an inflorescence called a syconium, which contains many tiny flowers. Each flower in the syconium has its own separate carpel, and as the fig develops, these carpels fuse together to form the edible structure of the fig fruit.In both examples, the multiple fruit is composed of numerous individual fruits, each derived from a separate ovary within the same flower. Multiple fruits are characteristic of certain plant families, such as the Bromeliaceae (pineapples) and the Moraceae (figs).

Question 32

Epigyny

Answer 32

Epigyny is a botanical term used to describe the arrangement of floral parts in which the ovary of a flower is situated above (superior to) the attachment point of the other floral parts (sepals, petals, and stamens). In other words, the sepals, petals, and stamens are attached below the ovary, which appears to be “over” or “on top” of these other floral parts.In flowers with epigynous structures:The sepals, petals, and stamens are attached to the receptacle below the ovary.The ovary is positioned above the attachment point of these other floral parts.The ovary may be partially or completely enclosed by the floral tube formed by the fused bases of the sepals, petals, and stamens.The style and stigma of the flower emerge from the top of the ovary.Epigyny is common in many angiosperm families, including the Asteraceae (daisy family), Fabaceae (pea family), and Solanaceae (nightshade family), among others. It is one of the three main types of floral symmetry, along with hypogyny (inferior ovary) and perigyny (half-inferior ovary). Epigyny is associated with various adaptations related to pollination, seed dispersal, and protection of reproductive structures.

Question 33

Hypogyny

Answer 33

Hypogyny is a botanical term used to describe the arrangement of floral parts in which the ovary of a flower is situated below (inferior to) the attachment point of the other floral parts (sepals, petals, and stamens). In other words, the sepals, petals, and stamens are attached above the ovary, which appears to be “below” or “underneath” these other floral parts.In flowers with hypogynous structures:The sepals, petals, and stamens are attached to the receptacle above the ovary.The ovary is positioned below the attachment point of these other floral parts.The ovary is typically not enclosed by the floral tube formed by the fused bases of the sepals, petals, and stamens.The style and stigma of the flower emerge from the top of the ovary.Hypogyny is a common floral arrangement in many angiosperm families, including the Rosaceae (rose family), Ranunculaceae (buttercup family), and Brassicaceae (mustard family), among others. It is one of the three main types of floral symmetry, along with epigyny (superior ovary) and perigyny (half-inferior ovary). Hypogyny is associated with various adaptations related to pollination, seed dispersal, and protection of reproductive structures.

Question 34

Protygyny

Answer 34

“Protygyny” is a botanical term used to describe the condition in which the stamens of a flower mature before the stigma is receptive to pollen. In other words, in protogynous flowers, the female reproductive structures (pistil, including the stigma) are not receptive to pollen when the male reproductive structures (stamens) shed pollen. This temporal separation of male and female reproductive functions helps to promote outcrossing and reduce the likelihood of self-fertilization within the same flower.Characteristics of protogynous flowers include:The stigma is not receptive to pollen when the flower first opens.The stigma becomes receptive to pollen after the stamens have shed pollen.This temporal separation of male and female reproductive functions can help to prevent self-fertilization and promote cross-pollination.Examples of protogynous species include many members of the Asteraceae (daisy family), such as sunflowers (Helianthus spp.), and certain members of the Fabaceae (pea family), such as beans (Phaseolus spp.).Protogyny is one of the various mechanisms that plants have evolved to ensure successful pollination and reproduction. It is particularly common in plant species with hermaphroditic flowers, where both male and female reproductive structures are present within the same flower.

Question 35

protandry and protogyny are not the same.

Answer 35

They are two different types of sequential hermaphroditism, referring to the temporal order of the maturation of reproductive structures within a flower.Protandry: In protandrous flowers, the male reproductive structures (stamens) mature and release pollen before the female reproductive structures (pistil, including the stigma) become receptive to pollen. This means that the flower functions first as a male (producing pollen) and then as a female (receptive to pollen). Protandry is common in plant species where self-fertilization is undesirable and cross-pollination is favored.Protogyny: In protogynous flowers, the female reproductive structures (pistil, including the stigma) become receptive to pollen before the male reproductive structures (stamens) shed pollen. This means that the flower functions first as a female (receptive to pollen) and then as a male (producing pollen). Protogyny is another mechanism to promote outcrossing and prevent self-fertilization in plants.In summary, protandry and protogyny are two different strategies employed by plants to temporally separate male and female reproductive functions within a flower, but they differ in the order of maturation of the reproductive structures.

Question 36

Perigyny

Answer 36

“Perigyny” is a botanical term used to describe the condition in which the sepals, petals, and stamens are attached to the receptacle in such a way that they appear to surround the ovary. In other words, the ovary is partially or completely enclosed by the floral tube formed by the fused bases of the sepals, petals, and stamens. The ovary may be either superior (above the attachment point of the other floral parts) or inferior (below the attachment point of the other floral parts).Characteristics of perigynous flowers include:The sepals, petals, and stamens are attached to the receptacle in a manner that forms a floral tube around the ovary.The ovary may be either superior or inferior, depending on the specific arrangement of floral parts.The style and stigma of the flower may emerge from the top of the ovary, above the attachment point of the other floral parts.Examples of perigynous flowers include those of the Rosaceae (rose family), such as roses (Rosa spp.) and strawberries (Fragaria spp.).Perigyny is one of the main types of floral symmetry, along with epigyny (superior ov

Question 37

Swollen shoot disease

Answer 37

Swollen shoot disease is a viral disease that primarily affects cacao trees (Theobroma cacao), which are cultivated for their seeds, which are used to make cocoa and chocolate. The disease is caused by the cacao swollen shoot virus (CSSV), which is transmitted by mealybugs (Planococcus citri) and other insect vectors.Swollen shoot disease is particularly prevalent in regions where cacao is grown, such as West Africa, including countries like Ghana, Côte d’Ivoire, and Nigeria, which are major producers of cacao beans. The disease can cause severe damage to cacao trees, leading to reduced yields and economic losses for cacao farmers.Efforts to control swollen shoot disease include planting disease-resistant cacao varieties, implementing strict sanitation practices to remove infected trees, and controlling insect vectors through the use of pesticides and cultural management practices. However, despite these efforts, swollen shoot disease remains a significant threat to cacao cultivation in affected regions.

Question 38

Haptotropism

Answer 38

Haptotropism is a type of tropism, which is the growth or movement of an organism in response to an external stimulus. In the case of haptotropism, the stimulus is physical contact or touch. Haptotropism is observed in plants, particularly climbing plants, where the direction of growth is influenced by contact with a solid support or substrate.When a plant encounters a solid support, such as a wall, trellis, or another plant, it responds by growing in a specific direction, often wrapping around the support structure. This directional growth towards the support is known as positive haptotropism. By attaching to a support, the plant gains stability and can access more light and resources for growth and reproduction.Examples of plants that exhibit haptotropism include vines like ivy and climbing plants like peas and beans. These plants use structures such as tendrils or twining stems to cling to supports and climb upwards. Haptotropism allows these plants to efficiently navigate their environment and exploit vertical spaces for growth and access to sunlight.

Question 39

Phototropism

Answer 39

1. Phototropism: Phototropism is the growth or movement of an organism in response to light. In plants, phototropism typically involves the bending or growth of plant parts towards a light source, such as the sun. This response allows plants to optimize their exposure to light for photosynthesis and growth.

Question 40

Thigmotropism

Answer 40

2. Thigmotropism: Thigmotropism is the growth or movement of an organism in response to touch or contact with solid objects. This is similar to the concept of haptotropism mentioned earlier. In plants, thigmotropic responses often involve directional growth towards or away from a physical surface, such as a wall or support structure. Thigmotropism allows plants to respond to mechanical stimuli and adapt their growth patterns accordingly.

Question 41

Shortest vein in the body

Answer 41

The shortest vein in the body is the hepatic vein. It carries deoxygenated blood from the liver to the inferior vena cava, which then returns the blood to the heart. While the length of veins can vary slightly among individuals, the hepatic vein is generally considered the shortest in the body due to its direct connection between the liver and the inferior vena cava.

Question 42

Hepatic portal vein

Answer 42

The hepatic portal vein is a blood vessel that plays a crucial role in the circulatory system. Here are key points about the hepatic portal vein:Location: The hepatic portal vein is a major blood vessel located in the abdominal cavity. It originates in the gastrointestinal tract and carries blood from the digestive organs to the liver.Composition: The hepatic portal vein is formed by the convergence of several veins, including the superior mesenteric vein and the splenic vein. It receives blood from the stomach, small intestine, large intestine, pancreas, and spleen.Function: The primary function of the hepatic portal vein is to transport nutrient-rich blood from the digestive organs to the liver for processing and detoxification. This includes nutrients absorbed from the small intestine, such as glucose, amino acids, vitamins, and minerals, as well as products of digestion and metabolic waste.Detoxification: In the liver, hepatocytes (liver cells) metabolize and detoxify substances absorbed from the digestive tract before they enter the systemic circulation. This includes filtering out toxins, drugs, and metabolic byproducts, as well as regulating blood glucose levels and storing excess nutrients.Regulation of Blood Glucose: The liver plays a central role in regulating blood glucose levels by storing excess glucose as glycogen or converting glycogen back into glucose as needed. The hepatic portal vein transports glucose absorbed from the digestive tract to the liver for storage or release into the bloodstream as necessary.Disease Implications: Disorders affecting the hepatic portal vein or liver function can have significant health implications. Conditions such as portal hypertension, liver cirrhosis, and liver disease can impair blood flow through the hepatic portal vein and compromise liver function, leading to serious complications.Overall, the hepatic portal vein is a vital component of the circulatory system, facilitating the transport of nutrients from the digestive organs to the liver for processing and detoxification, as well as playing a key role in regulating blood glucose levels and maintaining overall metabolic homeostasis.

Question 43

Rhizome

Answer 43

A plant with a horizontal underground stem is called a rhizome. Rhizomes are specialized stems that grow horizontally underground, often sending out roots and shoots from their nodes. These underground stems serve various functions for the plant, including vegetative reproduction, storage of nutrients, and the spread of the plant across its environment.

Question 44

Examples of plants with rhizomes include:

Answer 44

1. Ginger (Zingiber officinale): Ginger is a tropical plant known for its aromatic rhizomes, which are used both as a spice and in traditional medicine.
   
   2. Turmeric (Curcuma longa): Turmeric is another plant in the ginger family (Zingiberaceae) that produces rhizomes, which are dried and ground into a bright yellow spice commonly used in cooking and traditional medicine.
   3. Iris (Iris spp.): Many species of iris plants produce rhizomes that grow horizontally underground. These rhizomes give rise to new shoots and roots, allowing the plant to spread and form dense colonies.
   4. Bamboo (Bambusoideae): Bamboo is a type of grass that spreads through underground rhizomes, allowing it to quickly colonize an area and form dense thickets.
   5. Couch grass (Elymus repens): Couch grass, also known as quackgrass, is a common weed with rhizomes that spread rapidly underground, making it difficult to control in lawns and gardens.

Question 45

Montremes

Answer 45

Monotremes:
• Monotremes are a unique group of mammals that lay eggs instead of giving birth to live young.
• They are represented by only five extant species, including the platypus and echidnas.
• Monotremes are found in Australia and New Guinea.
• They have a combination of reptilian and mammalian characteristics, such as laying eggs and producing milk to feed their young.

Question 46

Marsupials:

Answer 46

• Marsupials are characterized by giving birth to relatively undeveloped young, which then continue to develop in a pouch called a marsupium.
• They are diverse and widespread, with representatives found in Australia, the Americas, and some parts of Asia and Africa.
• Iconic examples of marsupials include kangaroos, koalas, opossums, and Tasmanian devils.
• Marsupials exhibit a wide range of ecological adaptations and behaviors, from arboreal herbivores to terrestrial carnivores.

Question 47

Placentals:

Answer 47

• Placental mammals are the largest and most diverse group of mammals, characterized by giving birth to relatively well-developed young after a longer gestation period, during which the fetus is nourished via a placenta.
• They are found on every continent and in diverse habitats, including terrestrial, marine, and aerial environments.
• Placental mammals include familiar animals such as dogs, cats, elephants, whales, bats, and humans.
• They exhibit a wide range of morphological, physiological, and behavioral adaptations, allowing them to thrive in various environments and ecological niches.

Question 48

Cervical Vertebrae:

Answer 48

Cervical Vertebrae:
• Found in the neck region.
• Typically seven cervical vertebrae in most mammals, including humans.
• They support the weight of the head and allow for movement of the neck.

Question 49

Thoracic Vertebrae:

Answer 49

• Found in the upper back region, corresponding to the ribcage area.
• Typically twelve thoracic vertebrae in most mammals, including humans.
• They articulate with the ribs, forming the thoracic cage and providing protection for the vital organs in the chest cavity.

Question 50

Lumbar Vertebrae:

Answer 50

• Found in the lower back region, between the thoracic vertebrae and the sacrum.
• Typically five lumbar vertebrae in most mammals, including humans.
• They are larger and more robust than cervical vertebrae, providing support for the weight of the upper body and allowing for movement of the lower back.

Question 51

Sacral Vertebrae:

Answer 51

• Found in the pelvic region, between the lumbar vertebrae and the coccyx.
• Typically five sacral vertebrae in most mammals, including humans.
• They articulate with the pelvic bones, forming the sacroiliac joints and providing stability to the pelvis.

Question 52

Coccygeal Vertebrae (Coccyx):

Answer 52

• Found in the tail region, also known as the coccyx or tailbone.
• The number of coccygeal vertebrae varies among mammals, ranging from a single fused bone to several individual vertebrae.
• They provide support and flexibility to the tail and serve as attachment points for muscles and ligaments.

Question 53

Cervical Vertebrae:

Answer 53

• Cervical vertebrae have a relatively large vertebral foramen (the opening through which the spinal cord passes) compared to other vertebral regions.
• They typically have bifid (split) spinous processes, which provide attachment sites for muscles and ligaments that support the head and neck.
• Cervical vertebrae have transverse foramina, which allow passage of the vertebral artery and veins that supply blood to the brain.

Question 54

Thoracic Vertebrae:

Answer 54

• Thoracic vertebrae have facets on their sides for articulation with the ribs, forming the thoracic cage.
• They have long, downward-projecting spinous processes, which overlap and provide attachment for muscles and ligaments involved in posture and movement.
• Thoracic vertebrae are relatively rigid to provide stability and protection for the vital organs in the chest cavity.

Question 55

Lumbar Vertebrae:

Answer 55

• Lumbar vertebrae are the largest and most robust of the vertebral regions, reflecting their role in supporting the weight of the upper body.
• They have thick, stout spinous processes that project backward and provide attachment sites for powerful back muscles.
• Lumbar vertebrae have relatively large vertebral bodies, which help distribute the weight of the upper body and provide stability to the lower back.

Question 56

Sacral Vertebrae:

Answer 56

4. • Sacral vertebrae are fused together to form the sacrum, a triangular-shaped bone that articulates with the pelvic bones.
   • They have large, robust bodies with broad articular surfaces for articulation with the pelvic bones, providing stability to the pelvis.
   • The sacrum contains several pairs of sacral foramina, which allow passage of nerves and blood vessels to and from the pelvis and lower limbs.

Question 57

Coccygeal Vertebrae (Coccyx):

Answer 57

• Coccygeal vertebrae are typically small and rudimentary, often fused together to form a single bone called the coccyx or tailbone.
• They have reduced or absent spinous processes and transverse processes, reflecting their limited role in movement and weight-bearing.
• The coccyx serves as an attachment point for muscles and ligaments involved in supporting the pelvic floor and providing stability to the pelvis.

Question 58

Plant celll plasma membrane

Answer 58

Yes, plant cells, like all eukaryotic cells, have plasma membranes. The plasma membrane, also known as the cell membrane, is a vital component of plant cells and serves several important functions:Cell Boundary: The plasma membrane forms the outer boundary of the cell, separating the cell’s internal environment from its external surroundings. It acts as a barrier that controls the movement of substances into and out of the cell.Selective Permeability: The plasma membrane is selectively permeable, meaning it allows certain substances to pass through while restricting the passage of others. This selective permeability is crucial for maintaining internal homeostasis and regulating cellular processes.Transport: The plasma membrane contains proteins and channels that facilitate the transport of ions, nutrients, and other molecules across the membrane. This includes passive processes such as diffusion and osmosis, as well as active processes such as active transport and endocytosis.Cell Signaling: The plasma membrane contains receptors and signaling molecules that enable cells to communicate with each other and respond to external stimuli. This allows plants to sense changes in their environment and adjust their growth and development accordingly.Cell Adhesion: The plasma membrane also plays a role in cell adhesion, allowing adjacent cells to adhere to each other and form tissues and organs within the plant.In summary, the plasma membrane is a critical structure in plant cells, serving as a barrier, regulating the transport of substances, facilitating cell signaling, and contributing to cell adhesion and structure.

Question 59

Metameric segmentation

Answer 59

Metameric segmentation, also known as metamerism, is a characteristic feature found in many animals where the body is divided into repeating segments, or metameres. Each metamere typically contains a similar set of organs, structures, and associated nerves and blood vessels. This segmentation allows for greater flexibility and specialization of body regions, as well as improved efficiency in movement and coordination.

Key points about metameric segmentation include:

1.	Repeating Units: Metameric segmentation involves the repetition of body segments along the longitudinal axis of the animal. Each segment is similar in structure and function to adjacent segments, although they may be modified or specialized for specific roles.
2.	External Segmentation: In some animals, such as annelid worms (e.g., earthworms) and arthropods (e.g., insects), metameric segmentation is externally visible as a series of repeating units, or segments, along the body. These segments often contain paired appendages, such as legs or parapodia, which may be modified for various functions, such as locomotion, feeding, or sensory perception.
3.	Internal Segmentation: In other animals, such as vertebrates (including humans), metameric segmentation may be less apparent externally but is still present internally. In vertebrates, for example, the body is internally segmented into repeating units called somites, which give rise to structures such as vertebrae, ribs, and muscles. Although these segments may not be externally visible, they still represent a form of metameric segmentation.
4.	Advantages: Metameric segmentation provides several advantages for animals. It allows for greater flexibility and mobility, as each segment can move independently or in coordination with adjacent segments. It also allows for specialization of body regions for different functions, such as locomotion, feeding, reproduction, and defense. Additionally, metameric segmentation may facilitate rapid regeneration and repair of body parts in some animals.
5.	Evolutionary Significance: Metameric segmentation is believed to have evolved independently multiple times in different animal lineages, suggesting that it provides adaptive advantages for organisms living in diverse environments and ecological niches. The precise mechanisms and genetic pathways underlying metameric segmentation vary among different animal groups but often involve the activity of segmentation genes and signaling pathways.

Overall, metameric segmentation is a fundamental aspect of animal body organization, providing structural, functional, and evolutionary benefits to diverse animal species.

Question 60

Odontoid process

Answer 60

The vertebra that has a projection called the odontoid process is the second cervical vertebra, also known as the axis vertebra. The odontoid process, also called the dens, is a prominent bony projection that extends upward from the body of the axis vertebra. It serves as a pivot point for the rotation of the atlas (the first cervical vertebra) and allows for the nodding motion of the head. This specialized structure is crucial for the stability and range of motion of the cervical spine.

Question 61

Treating soil with lime

Answer 61

Treating soil with lime supplies it with calcium and/or magnesium ions. Lime, typically in the form of calcium carbonate (CaCO3) or magnesium carbonate (MgCO3), is commonly used to raise the pH of acidic soils and neutralize soil acidity. When lime is applied to the soil, it undergoes a chemical reaction with hydrogen ions (H+) in the soil solution, resulting in the formation of water and calcium ions (Ca2+) or magnesium ions (Mg2+), depending on the type of lime used.In addition to raising soil pH and neutralizing acidity, supplying calcium and magnesium ions through lime application can also:Improve soil structure by promoting flocculation (clumping) of soil particles.Enhance nutrient availability by reducing the toxicity of aluminum and manganese ions in acidic soils.Provide essential nutrients for plant growth, as calcium and magnesium are both important macronutrients required for various physiological processes in plants.Buffer soil pH fluctuations, helping to maintain a stable pH level over time.Overall, treating soil with lime can have several beneficial effects on soil fertility, structure, and plant growth, particularly in acidic soils where pH levels are low and nutrient availability may be limited.

Question 62

Haemophilia

Answer 62

The major cause of hemophilia is a deficiency or absence of specific proteins called clotting factors, which are essential for the blood clotting process. Hemophilia is typically caused by a genetic mutation that affects the production or function of clotting factors in the blood.There are two main types of hemophilia:Hemophilia A: This type is caused by a deficiency or defect in clotting factor VIII (factor 8), which is necessary for the formation of blood clots. Hemophilia A is the most common type of hemophilia, accounting for about 80-85% of cases.Hemophilia B: This type is caused by a deficiency or defect in clotting factor IX (factor 9), which is also essential for blood clotting. Hemophilia B is less common than hemophilia A, accounting for about 15-20% of cases.In both types of hemophilia, the lack of functional clotting factors impairs the blood clotting process, leading to prolonged bleeding and difficulty forming blood clots to stop bleeding after injury or trauma.Hemophilia is an inherited disorder, meaning it is passed down from parents to their children through genes. The genetic mutation responsible for hemophilia is located on the X chromosome, so the disorder primarily affects males. Females typically have two X chromosomes and are carriers of the hemophilia gene, but they are less likely to experience symptoms because they have a second X chromosome that may produce enough clotting factor to compensate for the deficiency.In summary, the major cause of hemophilia is a lack of functional clotting factors in the blood, specifically factor VIII (hemophilia A) or factor IX (hemophilia B), resulting from a genetic mutation inherited from one or both parents.

Question 63

Identical Twins (Monozygotic):

Answer 63

• Identical twins occur when a single fertilized egg (zygote) splits into two separate embryos during early development. This usually happens within the first two weeks after fertilization.
• As a result of the egg splitting, each embryo carries the same genetic material (DNA) and is genetically identical to the other. Identical twins are therefore always of the same sex and have nearly identical physical characteristics.
• Identical twins share a common placenta and gestational sac if the split occurs within the first few days after fertilization, but they may have separate placentas and gestational sacs if the split occurs later.

Question 64

Non-Identical Twins (Dizygotic):

Answer 64

• Non-identical twins occur when two separate eggs are fertilized by two separate sperm during the same menstrual cycle. Each fertilized egg develops into its own embryo, resulting in two genetically distinct individuals.
• Non-identical twins may or may not be of the same sex, and they share approximately 50% of their genetic material, similar to siblings born at different times.
• Non-identical twins each have their own placenta and gestational sac, as they develop from separate fertilized eggs.

Question 65

Operculate fish

Answer 65

are a type of fish that possess a structure called an operculum, which covers and protects the gills. When an operculate fish breathes, several physiological processes occur:Gill Ventilation: Operculate fish use a mechanism called buccal pumping to ventilate their gills. This involves rhythmic movements of the mouth and operculum to create a flow of water over the gills. When the fish opens its mouth, water is drawn into the buccal cavity. As the fish closes its mouth, the operculum swings outward, forcing water across the gills and out through openings called gill slits.Gas Exchange: As water flows over the gills, oxygen dissolved in the water diffuses across the thin epithelial surfaces of the gill filaments and into the bloodstream. At the same time, carbon dioxide produced by cellular respiration in the fish’s tissues diffuses out of the bloodstream and into the water. This process allows for efficient gas exchange, enabling the fish to obtain oxygen for respiration and remove carbon dioxide waste.Blood Circulation: The blood vessels within the gills transport oxygen-poor blood from the body to the gills, where it comes into close contact with the oxygen-rich water. Oxygen diffuses into the blood, while carbon dioxide diffuses out of the blood and into the water. Oxygen-rich blood is then pumped back to the body through the fish’s circulatory system to supply oxygen to tissues and organs.Regulation of Water Flow: The operculum plays a crucial role in regulating water flow over the gills. When the fish opens its mouth to breathe, the operculum swings outward, creating a negative pressure that draws water into the buccal cavity. As the fish closes its mouth and the operculum swings inward, water is forced across the gills and out through the gill slits. This ensures a continuous flow of oxygen-rich water over the gills for efficient gas exchange.In summary, when an operculate fish breathes, it uses buccal pumping to ventilate its gills, allowing for gas exchange between the water and the fish’s bloodstream. The operculum helps regulate water flow over the gills, ensuring efficient oxygen uptake and carbon dioxide removal for respiration.