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Question 1 Report
The common examples of trees found in the desert are
Answer Details
Deserts are characterized by their arid conditions, meaning they receive very little rainfall throughout the year. To survive in such environments, plants need special adaptations. Among the plant varieties, the trees commonly found in deserts include **cacti** and the **baobab tree**. Here's a brief explanation of why these trees are well-suited to desert environments:
Plants like **raffia palm**, **coconut**, **white and red mangrove**, and **shea-butter** trees are not typically found in desert environments because they require more moisture and different soil conditions compared to the harsh, dry lands of the desert.
Question 2 Report
In vascular plants, xylem tissue is responsible for
Answer Details
In vascular plants, the xylem tissue is primarily responsible for the transportation of water. The xylem functions like a network of tubes spreading throughout the plant, from the roots up to the leaves. Its main role is to carry water and dissolved minerals absorbed from the soil by the roots to other parts of the plant. This movement of water is crucial for maintaining plant health as it supports essential processes like photosynthesis and nutrient distribution. Unlike other tissues, xylem is specifically adapted for this task, with its elongated, tube-like structures which provide an effective passage for water movement.
Question 3 Report
Answer Details
The central nervous system (CNS) is a crucial part of the overall nervous system in the body, responsible for processing information and controlling most functions of the body and mind. It comprises the brain and the spinal cord.
1. Brain: The brain is the control center of the CNS. It is responsible for interpreting sensory information, coordinating movement, and managing functions such as thoughts, emotions, and memories. The brain oversees all voluntary and involuntary actions.
2. Spinal Cord: The spinal cord acts like a communication highway, transmitting signals between the brain and the rest of the body. It is essential for reflex actions and relays messages to and from the brain.
Together, the brain and spinal cord make up the central nervous system. Without this system, the body would not be able to respond appropriately to stimuli or maintain homeostasis. Thus, the correct components of the central nervous system are the brain and spinal cord.
Question 4 Report
The changes of living organisms over generation is referred to as
Answer Details
The process by which living organisms change over generations is referred to as organic evolution. This concept explains how species undergo gradual change over long periods of time, which can ultimately result in the emergence of new species. These changes are brought about by mechanisms such as mutation, natural selection, gene flow, and genetic drift. As a result, populations of organisms adapt to their environments and can become better suited to survive and reproduce. The concept of organic evolution is a fundamental principle in biology, as it helps us understand the history of life on Earth and the shared ancestry of all living organisms.
Question 5 Report
Body temperature, thirst and hunger are regulated by
Answer Details
The regulation of body temperature, thirst, and hunger is primarily managed by the hypothalamus. This is a small but crucial part of the brain located just below the thalamus. It plays a key role in maintaining the body's internal balance, known as homeostasis.
Here is a simple breakdown of its functions:
The hypothalamus achieves these regulations by interacting with the endocrine system, releasing hormones that affect various bodily functions. So, if you are thinking of which area of the brain is in charge of these vital processes, the answer is indeed the hypothalamus.
Question 6 Report
Which of the Nigeria states is Northern guinea savanna located?
Answer Details
The **Northern Guinea Savanna** is an ecological zone in Nigeria characterized by a mixture of grasslands and scattered trees. This vegetation belt lies between the Sudan Savanna in the north and the Southern Guinea Savanna in the south. The vegetation in this region is adapted to longer wet seasons compared to the Sudan Savanna and shorter ones compared to the Southern Guinea Savanna.
Among the states listed, **Kwara State** is where the **Northern Guinea Savanna** is located. Kwara is positioned in the north-central part of Nigeria, which aligns with the geographical location of the Northern Guinea Savanna. It features the characteristic landscape of mixed grasslands and trees, supporting both agriculture and livestock rearing.
In contrast, **Borno and Kano** are located further north, closer to or within the Sudan Savanna zone, which is more arid. **Oyo state**, on the other hand, is located in the southwestern part of Nigeria and is part of the forested regions or the Southern Guinea Savanna, which receives more rainfall and supports more dense vegetation compared to the Northern Guinea Savanna.
Thus, the correct answer is **Kwara State** as it lies within the **Northern Guinea Savanna** ecological zone.
Question 7 Report
Use the diagram above to answer the questions that follow
The part labelled I is
Answer Details
The part labelled I in the diagram is the oviduct.
To understand why it is the oviduct, let's first understand what an oviduct is. The oviduct, also known as the fallopian tube, is a tube-like structure that connects the ovary to the uterus in female mammals. Its main function is to transport eggs from the ovaries towards the uterus. Fertilization of the egg by sperm typically occurs within the oviduct.
Now, let's look at the structure of the other options:
Placenta: The placenta is an organ that develops in the uterus during pregnancy. It provides oxygen and nutrients to the growing baby and removes waste products from the baby's blood.
Amnion: The amnion is a thin membrane that forms a protective sac filled with amniotic fluid around the developing embryo or fetus.
Uterus: The uterus is a muscular organ where a fertilized egg implants and grows into a fetus during pregnancy.
Based on the description and location given by the diagram, part I is most consistent with the oviduct, as it is likely representing the tube-like structure leading from the ovary to the uterus.
Question 8 Report
The schlerenchyma tissues consist of
Answer Details
Schlerenchyma tissues are a type of plant tissue known for providing structural support. These tissues are composed of cells that are typically dead at maturity. The cell walls of schlerenchyma tissues are thickened with lignin, which makes them rigid and strong. These characteristics help in supporting the plant body and protecting the plant against external mechanical forces.
To clarify, let's consider the types of cells mentioned:
In summary, schlerenchyma tissues consist mainly of dead cells. Their primary role is structural support, making them distinct from tissues composed of living cells, tracheid cells, or meristematic cells.
Question 9 Report
One main feature of trees in the savanna habitat is the possession of
Answer Details
Trees in the savanna habitat have a typical characteristic that helps them survive in the unique conditions of this environment. One of the main features is the possession of thick, corky bark. Savannas often experience seasonal fires during the dry season. A thick, corky bark acts as a protective shield, insulating the tree from the intense heat and preventing damage to the vital inner tissues. This adaptation also helps minimize water loss by reducing evaporation, which is crucial in the savanna's typically dry conditions. Thus, the feature of thick, corky bark is essential for the survival and resilience of trees in the savanna.
Question 10 Report
Which of the following conditions causes aestivation in animals?
Answer Details
Aestivation is a state of dormancy or reduced activity that animals enter to survive in hot, dry conditions or when food or water is scarce.
Drought is a primary trigger for aestivation in animals, as it leads to water scarcity and increased temperatures.
While strong winds can be uncomfortable for animals, they don't typically trigger aestivation.
Rain is often associated with cooler temperatures and increased water availability.
Cold temperatures are more likely to trigger hibernation not aestivation.
Question 11 Report
Loamy soil is characterized by
Answer Details
Loamy soil is characterized by a distinct combination of features that make it particularly favorable for plant growth. It contains a balanced mixture of three types of soil particles: sand, silt, and clay. This combination gives loamy soil its unique properties.
High Humus: Loamy soil is known for having a high content of organic matter, often referred to as humus. Humus is important because it improves soil fertility, provides vital nutrients for plants, and helps retain moisture.
Moderate Porosity: Loamy soil has a structure that provides moderate porosity. This means it can hold water effectively while also allowing excess water to drain away, ensuring that plants have both the water and air they need. It balances water retention and aeration very well.
Because of these characteristics, loamy soil is considered one of the best soils for agriculture and gardening. Therefore, the description that best characterizes loamy soil is high humus and moderate porosity.
Question 12 Report
Which of these pair of substances must be present for a seed to germinate in a laboratory set-up?
Answer Details
For a seed to germinate in a laboratory set-up, the key pair of substances required are heat and water.
Water is essential because it activates the enzymes that begin the germination process. When a seed absorbs water, it swells and breaks the seed coat. This process is known as imbibition, and it is the first step in germination. The absorbed water allows the enzymes to start breaking down stored food resources within the seed, providing the energy necessary for the growth of the embryonic plant.
Heat, on the other hand, is important because most seeds need to be within a certain temperature range to germinate effectively. Appropriate warmth can facilitate enzymatic activities and biochemical processes needed for growth. The required temperature varies between species, but generally, seeds need warmth to sprout successfully.
While microbes can contribute to soil fertility and the decomposition of organic material, they are not directly necessary for the germination process of seeds, nor is soil required in a controlled laboratory environment.
Similarly, while manure can provide nutrients in an outdoor setting, it is not a vital component in the controlled germination process in a lab. The focus in such controlled experiments is typically on the primary resources that directly aid in the seed's initial growth, namely water and suitable temperature from heat.
Question 13 Report
Blood group AB is considered as universal recipient because they can receive blood from groups
Answer Details
Blood group AB is considered a universal recipient because individuals with this blood type can receive blood from all other blood groups, including A, B, AB, and O. This is possible due to the presence of both A and B antigens on the surface of their red blood cells and the absence of anti-A and anti-B antibodies in their plasma.
Here’s a simple breakdown:
This makes AB blood group the universal recipient as they can accept A, B, AB, and O blood, without experiencing adverse reactions caused by antibody-antigen incompatibility.
Question 14 Report
Use the diagram above to answer the question that follows
The diagram demonstrates
Answer Details
Thigmotropism is a directional growth movement which occurs as a mechanosensory response to a touch stimulus. Mechanosensory responses in plants are the ways that plants move or change shape in response to touch, wind, or other mechanical stimuli.
Phototropism is the ability of plants to grow towards or away from light, which is a vital adaptive process for plants.
Geotropism is the growth of the parts of plants in response to the force of gravity.
Hydrotropism is a plant's growth response in which the direction of growth is determined by a stimulus or gradient in water concentration. It is the growth or turning of plant roots towards or away from moisture.
Question 15 Report
A common component of blood and lymph is
Answer Details
Blood and lymph are both crucial components of the circulatory and immune systems in the body. One of the key components that is common to both blood and lymph is the white blood cell. Here's how:
White blood cells, also known as leukocytes, play a significant role in defending the body against infections, diseases, and foreign invaders. They are an essential part of the immune system.
In blood, white blood cells circulate through the cardiovascular system and help in identifying and attacking pathogens like bacteria, viruses, and other harmful microorganisms.
In lymph, white blood cells are found in the lymphatic fluid and lymph nodes, where they help filter and trap pathogens, preventing them from spreading further into the body.
Therefore, white blood cells are the common component of both blood and lymph, playing a crucial role in the body's defense mechanisms.
Question 16 Report
One of the following is an example of discontinuous variation
Answer Details
Discontinuous variation refers to variations where the traits are distinct and categorical, meaning individuals can be grouped into distinct categories with no intermediate states. A good example of **discontinuous variation** from the options provided is **blood group**. This is because blood groups are distinct categories (e.g., A, B, AB, O) and individuals belong to one category without any intermediate states.
In contrast, other traits like **shape of the head**, **body complexion**, and **pointed nose** often show a range of variations that are continuous, meaning these traits can have many intermediate forms and cannot be easily categorized into discrete categories. Therefore, **blood group** is an **example of discontinuous variation** because it consists of clearly defined and non-overlapping categories.
Question 17 Report
The rhizoid of liverwort is
Answer Details
The rhizoid of liverwort is unicellular and unbranched.
Here's a simple explanation: Liverworts are a type of non-vascular plant that have structures called rhizoids. These rhizoids look like tiny hairs and they help the plant attach to surfaces like rocks or soil. Even though they help with attachment, they do not have the complexity of true roots.
In liverworts, these rhizoids are formed as single cells, which means they are unicellular. Think of them as being like a single long cell that looks like a hair. This single-celled structure is unbranched, meaning it doesn't split or divide into more parts or sections.
In summary, liverwort rhizoids are unicellular and unbranched, helping them secure the plant to various surfaces without forming complex root structures.
Question 18 Report
DNA carries the genetic information and are generally found in the
Answer Details
DNA, which stands for Deoxyribonucleic Acid, is the molecule that contains the genetic instructions for the development, functioning, growth, and reproduction of all known living organisms and many viruses. It is often referred to as the blueprint of life because it holds the instructions needed to build and maintain an organism.
DNA is primarily found in the chromosomes within the cell nucleus. Chromosomes are long, thread-like structures made of protein and a single molecule of DNA. Every human cell, for example, typically contains 23 pairs of chromosomes, amounting to a total of 46. These chromosomes are distributed evenly when cells divide, ensuring that each new cell contains a complete set of genetic information.
Other components like ribosomes, blood, and enzymes do not contain DNA in the way chromosomes do. Ribosomes are cellular structures responsible for protein synthesis, blood is a body fluid important for transporting nutrients and oxygen, and enzymes are proteins that catalyze biochemical reactions. While they all perform essential roles within the organism, they do not serve as carriers of genetic information.
Question 19 Report
Use the diagram above to answer the question that follows
The organ is responsible for
Answer Details
Since I do not have access to the diagram mentioned, I will explain all the functions listed and how they relate to specific organs. You can then match the explanation with the organ shown in the diagram.
Identify the organ in the diagram and match it with the corresponding function explained above.
Question 20 Report
Which of the following factors can lead to overcrowding?
Answer Details
To understand overcrowding, we need to consider factors that increase or decrease a population within a certain area.
High natality refers to a high birth rate. When more individuals are born in an area than those leaving it, the population will naturally increase, potentially leading to overcrowding as the area becomes inhabited by more individuals than it can comfortably support. This is because more births without corresponding departures or deaths means more people vying for the same resources.
Emigration is the process of individuals moving out of a given area to live elsewhere. This movement decreases the population of an area, which would typically help prevent overcrowding rather than cause it. Hence, emigration does not lead to overcrowding.
Competition involves individuals or species competing for limited resources such as food, water, or territory. While it does not directly cause overcrowding, high population density due to overcrowding can intensify competition since more individuals fight for the same scarce resources. Thus, competition is more of a consequence rather than a direct cause of overcrowding.
High mortality means a high death rate. This reduces the number of individuals in a population, which works against overcrowding. With more individuals dying, the population decreases or stabilizes, alleviating pressures that lead to overcrowding.
In summary, among the listed factors, high natality is the most significant contributor to overcrowding as it directly increases population size when not matched by increased emigration or mortality.
Question 21 Report
The organisms that adopt swarming as an adaptation to overcome overcrowding are
Answer Details
Among the organisms listed, termites are well-known for adopting swarming as an adaptation to overcome overcrowding.
Here's why:
Swarming in termites is a crucial natural strategy that allows them to efficiently manage their population and ensure the survival and expansion of their colonies.
Question 22 Report
The cell organelle responsible for the synthesis of protein is the
Answer Details
The cell organelle responsible for the synthesis of protein is the ribosome.
To put it simply, ribosomes are like tiny factories within the cell. They read the genetic instructions carried by messenger RNA (mRNA) and use these instructions to assemble amino acids into proteins, which are essential molecules for various cell functions.
Here's how it works in a straightforward manner:
In summary, the ribosome is an essential organelle for protein synthesis, which is crucial for the cell's structure, function, and regulation of the body's tissues and organs.
Question 23 Report
One of the ways of controlling Schistosomiasis is by
Answer Details
One effective way of controlling Schistosomiasis is by destroying water snails and water weeds.
Schistosomiasis, also known as bilharzia, is a parasitic disease caused by trematode worms of the genus Schistosoma. The life cycle of these parasites heavily involves freshwater snails, which act as intermediate hosts. Here's how the life cycle works:
By destroying water snails and eliminating water weeds, which can provide habitat for these snails, you interrupt the lifecycle of the parasite. This can significantly reduce the risk of transmission to humans. It is crucial to control snail populations in freshwater bodies where human contact is common.
This method, along with other control measures such as providing access to safe water, improving sanitation, and educating communities about safe water practices, plays a crucial role in reducing schistosomiasis transmission. Importantly, to combat the disease effectively, a combination of approaches is usually necessary.
Question 24 Report
A fruit formed from one flower with many carpels is referred to as
Answer Details
A fruit formed from one flower with many carpels is referred to as an aggregate fruit.
Let me break that down further for clarity: When a single flower contains multiple ovaries (carpels), each of these ovaries can develop into a small fruit. These small fruits collectively form what is known as an aggregate fruit. This means that although the fruit appears to be one single entity, it is actually made up of many small fruits that are clustered together. Each small fruit in the cluster originates from a single ovary of the flower.
An example of an aggregate fruit is a raspberry or a blackberry, where the clustered small fruits can easily be observed.
Question 25 Report
I
6 X + 6 H2 O → C6 H12 O6 + 6O2
III chlorophyll II IV
Use the diagram above to answer question that follows
The part labelled I is
Answer Details
The part labelled I in the given equation refers to sunlight.
Here is why:
The equation you've provided represents the chemical process of photosynthesis, which is how plants convert light energy into chemical energy stored in glucose (C6H12O6). This process occurs in the chloroplasts of plant cells.
Sunlight is essential in this process because it provides the energy needed for photosynthesis to occur. This process begins when chlorophyll (labelled as III) within the chloroplasts absorbs sunlight, enabling the transformation of carbon dioxide (CO2) and water (H2O) into glucose and oxygen (O2).
In summary, the part labelled I is sunlight because it is the energy source that drives the entire reaction of photosynthesis.
Question 26 Report
The oxygen transported to all parts of the body during blood circulation is used for the
Answer Details
The oxygen that is transported to all parts of the body during blood circulation is primarily used for the release of energy from food. This process is also known as cellular respiration.
Here's how it works:
Thus, the presence of oxygen is vital for cells to convert the energy stored in food into a form that can be used for all activities, from metabolic processes to muscle contraction. In summary, the primary purpose of oxygen transportation during blood circulation is for the release of energy from food, which is essential for maintaining life and performing all physiological functions.
Question 27 Report
Reproduction in paramecium is by
Answer Details
Paramecium is a single-celled organism that belongs to the group of protists known as ciliates. The primary method of reproduction in paramecium is through binary fission. Let's break down what that means:
Binary Fission: This is a type of asexual reproduction, which means it does not involve the fusion of gametes (sperm and egg). Instead, it is a simple division process in which the organism creates a copy of itself. Here is how it works in paramecium:
This process of binary fission allows paramecia to reproduce quickly and efficiently, leading to exponential population growth under favorable conditions. Unlike other methods like budding, spore formation, or fragmentation, binary fission is a straightforward division of the cell into two identical parts.
Conclusion: Paramecium reproduces mainly by binary fission, a type of asexual reproduction that results in two genetically identical offspring from a single parent organism.
Question 28 Report
Infectious diseases are caused by
Answer Details
Infectious diseases are illnesses caused by certain harmful microorganisms that invade the body. These microorganisms can be grouped into several categories. Among these categories, two of the most notable are bacteria and protozoa. Both of these groups contain species that can lead to disease.
Bacteria are single-celled microorganisms. While many bacteria are harmless or even beneficial to humans, some can cause diseases such as strep throat, tuberculosis, and urinary tract infections. Bacteria are living organisms that reproduce by themselves, and they can sometimes produce toxins that harm the host.
Protozoa are a diverse group of single-celled organisms that live in a variety of moist or aquatic environments. Many protozoa are harmless, but some can cause serious diseases. For example, the protozoan parasite Plasmodium causes malaria, a serious disease transmitted by mosquitoes.
Protists is a broader term that includes protozoa as well as algae and fungi-like organisms, and while not all protists cause disease, the term could refer to certain disease-causing protozoans.
Amoebas are a type of protozoan characterized by their changing shape and movement. Although many amoebas are harmless, some types, such as Entamoeba histolytica, cause illnesses like amoebic dysentery, which is characterized by diarrhea and stomach pain.
In summary, infectious diseases can be caused by bacteria and a variety of protozoa, including specific types like amoebas. Understanding these different microorganisms helps in diagnosing and treating the diseases they cause.
Question 29 Report
The part of the kidney where the selective reabsorption takes place is
Answer Details
The part of the kidney where selective reabsorption takes place is the Henle's loop, also known as the Loop of Henle.
Here's a simple explanation:
The kidneys are responsible for filtering blood, removing waste, and balancing bodily fluids. This is accomplished through structures called nephrons, each of which functions like a tiny processing plant. A nephron comprises various parts, including the glomerulus, Bowman's capsule, and the Loop of Henle.
Initially, blood is filtered in the glomerulus, and the resulting fluid then enters the Bowman's capsule. However, this fluid contains essential nutrients and ions that our body needs. Therefore, it must be reabsorbed back into the bloodstream.
The Loop of Henle plays a critical role in this reabsorption process. It creates a concentration gradient that allows water, sodium, chloride ions, and other substances to be reabsorbed selectively into the blood. This ensures that vital nutrients and electrolytes are not lost in the urine.
The Henle's loop is integral in forming concentrated urine, enabling the body to conserve water and important nutrients while still eliminating waste effectively. Thus, it is the site where selective reabsorption primarily occurs.
Question 30 Report
If the F1 generation allows for self-pollination, what will be the genotypic ratio of the offspring?
Answer Details
To determine the genotypic ratio of the offspring when the F1 generation allows for self-pollination, first understand the process of Mendelian genetics. In a typical monohybrid cross, let's assume two homozygous parents, one dominant (AA) and one recessive (aa). When these two are crossed, the F1 generation will all have the genotype Aa, which is heterozygous.
If we allow the F1 generation (Aa) to self-pollinate, crossing Aa with Aa, the potential genotypes of the offspring can be determined using a Punnett square:
| A | a | |
| A | AA | Aa |
| a | Aa | aa |
From this Punnett square, you can see the possible combinations:
Thus, the genotypic ratio of the offspring is 1 : 2 : 1, which represents one homozygous dominant (AA), two heterozygous (Aa), and one homozygous recessive (aa).
Question 31 Report
Answer Details
The main excretory products of plants during metabolism are carbon dioxide, excess water, and nitrogenous compounds.
Plants produce carbon dioxide as a metabolic waste product during respiration, while oxygen is a metabolic waste product from photosynthesis. Excretion of gaseous waste in plants takes place through stomatal pores on leaves. Oxygen released during photosynthesis is used for respiration while carbon dioxide released during respiration is used for photosynthesis.
Question 32 Report
The part of the brain that receives sensory impulses of smell is the
Answer Details
The part of the brain that receives sensory impulses of smell is the olfactory lobe. When you perceive a scent, information from the nose's sensory cells is sent to the olfactory lobe, and it is here that the brain begins the process of identifying the fragrance. The olfactory bulb is the first region that processes smell sensory data, allowing you to discern various odors. Other parts of the brain, like the cerebrum, help process and associate these smells with memories or emotions, but the olfactory lobe is the initial receiver of these sensory signals related to smell.
Question 33 Report
Which of the following plant is found in the ground layer of a tropical rainforest in Nigeria?
Answer Details
In a tropical rainforest, the forest layers are characterized by distinct types of vegetation. The **ground layer** hosts plants and organisms that typically thrive in low-light conditions due to the dense canopy above. Such layers often consist of mosses, ferns, and small plants that can grow with limited sunlight.
When considering the plants listed:
Thus, the answer is **liverwort**, as it appropriately matches the ecological niche of the **ground layer** in a tropical rainforest.
Question 34 Report
Cell division that involves the growth, development, repairs and replacement of worn out tissues is
Answer Details
The type of cell division that involves the growth, development, repair, and replacement of worn-out tissues is mitosis.
Mitosis is a process by which a single cell divides to produce two identical daughter cells. This process is crucial for several reasons:
The process involves several phases, including prophase, metaphase, anaphase, and telophase, each contributing to the accurate duplication and distribution of chromosomes to the daughter cells.
Question 35 Report
Which of the following evidences of evolution employs the use of radio-isotope dating?
Answer Details
The evidence of evolution that employs the use of radio-isotope dating is fossil records.
Let me explain this further. Fossils are the preserved remains or traces of organisms that lived in the past. Scientists use fossils to understand the history of life on Earth and how species have changed over time. But to make meaningful conclusions, they need to know the age of these fossils.
This is where radio-isotope dating comes into play. Radio-isotope dating, also known as radiometric dating, is a technique used to determine the age of rocks and fossils. It measures the decay of radioactive isotopes in materials.
Here's a simple way to understand it: you can think of radioactive isotopes as tiny clocks contained within rocks and fossils. These isotopes decay at a constant rate over time. By measuring the amount of remaining isotopes and knowing their half-life (the time it takes for half of the isotopes to decay), scientists can calculate how long the isotopes have been decaying. This gives them the age of the fossil or rock, helping to place it in the context of Earth's history.
In conclusion, fossil records are the evidence of evolution that utilize radio-isotope dating to provide a time frame and chronological context for evolutionary events.
Question 36 Report
In blood transfusion, a patient with group AB receives
Answer Details
In blood transfusion, a patient with blood type **AB** is known as a **universal recipient**. This means they can receive red blood cells from any blood group. This is because:
Therefore, a person with blood type AB can safely receive red blood cells from **donors with A, B, AB, and O blood types**. This is because:
Therefore, a patient with blood type AB can receive blood from donors with **group O, A, B, or AB**.
Question 37 Report
The formation of cilia and flagella in living cells is carried out with the help of
Answer Details
The formation of cilia and flagella in living cells is primarily carried out with the help of centrioles.
In eukaryotic cells, cilia and flagella are long, hair-like structures that extend from the surface of the cell and are responsible for movement. They are made up of microtubules, which are protein structures. The base of a cilium or a flagellum is anchored to a cell by a structure called the basal body.
The basal body is very similar in structure to a centriole. Centrioles are cylinder-shaped organelles found in animal cells and are composed of microtubule triplets. When a cell is ready to produce cilia or flagella, the centrioles migrate to the surface of the cell and become basal bodies by aiding in the assembly and organization of these microtubules.
Therefore, the role of centrioles is crucial because they act as the organizing centers for the microtubule structures that comprise cilia and flagella. Without centrioles, a cell would not be able to form these important structures.
Question 38 Report
An example of organism that exhibits counter-shading to escape from its predator is
Answer Details
An example of an organism that exhibits counter-shading to escape from predators is a fish. Counter-shading is a type of camouflage where an animal has a darker coloration on its upper side and a lighter coloration on its underside.
This adaptation helps fish in two main ways:
This dual blending effect helps fish to reduce the risk of being detected by predators, enhancing its chances of survival. This strategy is particularly beneficial in open water habitats where there are few places to hide.
Question 39 Report
Answer Details
In a genetic cross, when we have a heterozygous red flower plant (Rr) and a white flowered plant (rr), we can use a Punnett square to determine the probability of each possible genotype of the offspring.
The parent genotypes are:
We can set up a Punnett square with the following alleles:
| r | r | |
|---|---|---|
| R | Rr | Rr |
| r | rr | rr |
From the table, we can see the following possible outcomes for the offspring:
Therefore, the probability that the offspring will be Rr is 2 out of 4 (or 1/2).
Question 40 Report
Which of the following structures enables the exchange of gases in insects?
Answer Details
Insects have a specialized system for gas exchange, which does not rely on their skin like some other small organisms. Instead, they use a system known as the tracheal system. This system consists of a network of tiny tubes called tracheae.
The tracheae are the main structures that enable the exchange of gases in insects. These tubes extend throughout an insect's body and open to the outside through small openings on the insect's exoskeleton called spiracles.
When an insect breathes, air enters through the spiracles and travels through the tracheae, delivering oxygen directly to the body’s cells. At the same time, carbon dioxide, which is a waste product of respiration, exits the cells via the same tracheal system, leaving the body through the spiracles.
The tracheal system is highly efficient in distributing air directly to the tissues, bypassing the need for a circulatory system to transport gases throughout the body. As such, it provides a direct and effective way for insects to exchange gases necessary for respiration.
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