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Question 1 Rapport
The rhizoid of liverwort is
Détails de la réponse
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 2 Rapport
Détails de la réponse
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 3 Rapport
The endocrine gland that is called the master gland is the
Détails de la réponse
The **pituitary gland** is known as the **"master gland"** of the endocrine system. Let us explore why this is important in a simple way.
The pituitary gland is a tiny, pea-sized organ located at the base of the brain, right behind the bridge of the nose. Despite its small size, it plays a crucial role in regulating vital body functions and general wellbeing.
Why is it called the master gland?
In summary, the pituitary gland is termed the "master gland" because it has the ability to control many other glands within the endocrine system, playing a pivotal role in maintaining the body's environment or homeostasis.
Question 4 Rapport
The common examples of trees found in the desert are
Détails de la réponse
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 5 Rapport
The pigment carrying oxygen in the blood is
Détails de la réponse
The pigment responsible for carrying oxygen in the blood is haemoglobin. Haemoglobin is a complex protein found in red blood cells. Its primary function is to transport oxygen from the lungs to the rest of the body and return carbon dioxide from the body to the lungs for exhalation. Each haemoglobin molecule can bind to four oxygen molecules, allowing it to carry and efficiently distribute a large amount of oxygen throughout the body.
Here's a simple explanation of how it works:
It is essential to note that while oxyhaemoglobin is simply haemoglobin that has combined with oxygen, the fundamental oxygen-carrying pigment itself is still haemoglobin.
Question 6 Rapport
The type of variation where there are no remarkable differences between the two extreme individuals is called
Détails de la réponse
The type of variation where there are no remarkable differences between the two extreme individuals is called continuous variation.
In biology, variation refers to the differences among individuals within a population. When we refer to continuous variation, we're talking about traits that are measured on a scale and show a range of small differences between individuals. An example is human height or weight. In these cases, individuals do not fall into a finite or distinct number of categories, but rather display a smooth and gradual transition across a range.
This type of variation typically results from the combined effects of many genes (polygenic inheritance) and the influence of environmental factors. It presents as a continuous range of expression, forming a bell-shaped curve when graphed, rather than discrete categories. Because of this smooth transition without sharp differences, it's termed as continuous variation.
Question 7 Rapport
In glycolysis, glucose is broken down through series of reactions in the presence of enzyme and absence of oxygen to produce
Détails de la réponse
Glycolysis is a biochemical process through which glucose, a six-carbon sugar, is broken down into two molecules of a three-carbon compound called **pyruvic acid** or **pyruvate**. This process occurs in the **absence of oxygen** and is also referred to as anaerobic respiration. During glycolysis, energy stored in glucose is released, and a net gain of **two molecules of ATP (adenosine triphosphate)** is produced, which serves as a direct energy source for cellular activities.
Here is a brief explanation of the main steps involved in glycolysis:
In summary, during glycolysis in the absence of oxygen, glucose is transformed into **pyruvic acid and a net gain of ATP molecules**, making the answer **pyruvic acid + ATP**.
Question 8 Rapport
Bilateral symmetry,cylindrical bodies and double openings are characteristic features of
Détails de la réponse
The features you mentioned, namely bilateral symmetry, cylindrical bodies, and double openings, are characteristic of nematodes.
Let's break it down further:
In contrast:
Therefore, based on these descriptions, nematodes clearly align with the features of bilateral symmetry, cylindrical bodies, and double openings.
Question 9 Rapport
In which zone of the marine habitat does the organisms require adaptation for attachment?
Détails de la réponse
The marine habitat is divided into various zones, each with its own environmental conditions and challenges for the organisms living there. Among these zones, the intertidal zone is the one where organisms require significant adaptation for attachment. The intertidal zone is the area that is exposed to the air at low tide and submerged under water at high tide.
The main reasons organisms need adaptations for attachment in this zone are:
Therefore, the intertidal zone specifically requires organisms to have adaptations that ensure they remain securely attached despite the dynamic and challenging conditions encountered daily.
Question 10 Rapport
Production of healthier offspring, viable seeds and formation of new varieties are good characteristics
Détails de la réponse
Cross-pollination is a type of pollination that produces healthier offspring, viable seeds, and new varieties.
Cross-pollination involves the transfer of pollen from the anther of one flower to the stigma of a different flower. In contrast, self-pollination is when pollen is transferred within a flower or between flowers on the same plant. Self-pollination is effective in a stable environment, but it can lead to weak offspring that are less adapted to the environment.
Question 11 Rapport
A trait that is always expressed during crossing of hereditary characteristics is
Détails de la réponse
When discussing the crossing of hereditary characteristics, a trait that is always expressed is known as a dominant trait. In genetics, traits are determined by genes, and each trait has two alleles, one from each parent. Alleles can either be dominant or recessive.
Dominant traits are those that are expressed in the organism's phenotype when at least one allele for the trait is dominant. This means that even if the organism has one dominant and one recessive allele for a trait, the dominant trait will take precedence and be observed in the individual.
Conversely, a recessive trait is only manifested in the phenotype if both alleles for that trait are recessive. Therefore, when a dominant allele is present, it will mask the expression of a recessive allele, resulting in the dominance of the trait in question.
For example, if a plant has one allele for tall height (dominant) and one for short height (recessive), the plant will appear tall because the tall allele is dominant.
Question 12 Rapport
Blood group AB is considered as universal recipient because they can receive blood from groups
Détails de la réponse
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 13 Rapport
The bacteria in the large intestine of man synthesizes
Détails de la réponse
The large intestine of humans is home to a diverse community of beneficial bacteria. These bacteria primarily synthesize vitamins, particularly vitamin K and some of the B vitamins, such as B12. They do not typically produce minerals or glucose.
Here's a simple breakdown:
Thus, the correct and simplest answer is that the bacteria in the large intestine primarily synthesize vitamins.
Question 14 Rapport
An instrument used for measuring the intensity of light
Détails de la réponse
The instrument used for measuring the **intensity of light** is a **photometer**.
Let me explain this in a simple way:
A **photometer** is a device that is specifically designed to measure the **strength or intensity** of light. It helps in determining how bright or dim a light source is. These devices are widely used in various fields such as photography, biology, and astronomy where measuring light intensity is crucial. Photometers can measure different wavelengths of light, including visible light, and sometimes UV or infrared light, depending on the type.
For comparison, let’s briefly learn about the other instruments mentioned:
As you can see, none of these instruments are designed to measure light intensity. Therefore, the correct instrument for measuring the **intensity of light** is the **photometer**.
Question 15 Rapport
Use the diagram above to answer the questions that follow
The part labelled I is
Détails de la réponse
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 16 Rapport
Loamy soil is characterized by
Détails de la réponse
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 17 Rapport
Which of the following plant is found in the ground layer of a tropical rainforest in Nigeria?
Détails de la réponse
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 18 Rapport
Which of the following processes takes place in the carbon cycle?
Détails de la réponse
The carbon cycle is a natural process through which carbon is exchanged between different components of the Earth, including the atmosphere, oceans, soil, and living organisms. The process in the carbon cycle related to your question is combustion.
Combustion is the process of burning organic material such as fossil fuels (coal, oil, and natural gas) or biomass (like wood). When these materials are burned, they react with oxygen to produce energy, releasing carbon dioxide (CO2) and water vapor as by-products. This carbon dioxide is then released into the atmosphere, where it can be absorbed by plants through photosynthesis, thereby continuing the carbon cycle.
To clarify why the other processes are not part of the carbon cycle:
In summary, combustion is the process in the list above that plays a direct role in the carbon cycle by releasing carbon dioxide into the atmosphere.
Question 19 Rapport
The schlerenchyma tissues consist of
Détails de la réponse
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 20 Rapport
Which of the following evidences of evolution employs the use of radio-isotope dating?
Détails de la réponse
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 21 Rapport
Détails de la réponse
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 22 Rapport
Ecological succession can result from
Détails de la réponse
Ecological succession is a natural process by which ecosystems change and develop over time. This process can be initiated by several factors, resulting in the gradual replacement of one community by another until a stable ecosystem, known as a climax community, is achieved.
One such factor that can lead to ecological succession is a newly formed habitat. When an area is newly formed, such as from a volcanic eruption creating new land, or when a glacier retreats exposing bare rock, there is no pre-existing community. Over time, pioneer species such as lichens and mosses begin to colonize the area. As they die and decompose, they contribute organic matter to the soil, making it more hospitable for future plant species. This leads to the gradual development of a more complex community.
A habitat with abundant food might not directly cause ecological succession, but it can support the growth and reproduction of organisms, contributing to the stability and complexity of existing ecosystems. However, changes in food availability can lead to shifts in populations and species interactions, indirectly influencing successional changes.
Another important factor is a habitat with space and light. When a disturbance such as a fire clears an area, removing trees and other vegetation, it creates open space and increases light availability. This situation allows new species to colonize the area, starting a process known as secondary succession. Initially, fast-growing species that require a lot of light dominate the area, but eventually, as the ecosystem matures, it becomes more diverse and balanced.
Lastly, a population of plants on fertile land provides a suitable environment for ecological succession. Fertile soils support a wide variety of plant species, which contribute to the formation of a complex and stable ecosystem over time. As plants grow and die, they enrich the soil, promoting the growth of secondary species until a mature community is established.
In summary, ecological succession can result from newly formed habitats, disturbances that create space and light, and fertile lands. These changes create conditions that allow different species to colonize and thrive, leading to the evolution of ecosystems over time.
Question 23 Rapport
A medium texture soil with high organic matter is
Détails de la réponse
A medium texture soil with high organic matter is best described as loamy soil. Here is why:
Loamy soil is a mix of three main soil types: sand, silt, and clay. This combination creates a soil that is rich in organic matter and nutrients, providing an excellent environment for plant growth.
Key Characteristics of Loamy Soil:
Understanding the benefits and characteristics of loamy soil can help in recognizing its importance in agriculture and gardening. Unlike clay or sandy soils, which might have issues with drainage or nutrient retention respectively, loamy soil offers a balance that is conducive for a wide variety of plants.
Question 24 Rapport
Détails de la réponse
The first organisms on Earth are widely believed to have evolved from aquatic habitats. This conclusion is based on several scientific observations and theories.
1. **Early Earth Conditions:** When Earth was still a young planet, conditions were harsh, with a very hot climate and volcanic activity. During this time, the planet's surface was largely covered by oceans which provided a stable environment where simple life forms could potentially thrive. The presence of water is essential because it acts as a medium for chemical reactions and life-supporting processes.
2. **Chemistry of Life:** Water is a solvent that facilitates the necessary chemical reactions required for life. In aquatic environments, organic molecules could dissolve in water, leading to complex chemical reactions, leading to the formation of proteins, lipids, and nucleic acids, which are building blocks of life.
3. **Abiogenesis and the "Primordial Soup" Theory:** One theory of how life began is called the "primordial soup" theory, which suggests that life originated through chemical reactions in the ocean. This soup-like mixture of organic compounds provided the ideal conditions for the first living organisms to form.
4. **Evidence from Fossils:** The oldest known fossils are those of simple microorganisms such as bacteria. These fossils have been found in ancient sedimentary rocks, which were formed in water.
In summary, while there are different types of habitats available on Earth now, the initial conditions billions of years ago favored the formation of life in an aquatic environment. Therefore, it is widely accepted that the earliest life forms evolved in the aquatic habitat.
Question 25 Rapport
Détails de la réponse
Iron is a crucial nutrient for plants due to its involvement in several important biological processes. Let's break these down:
In summary, iron is crucial because it is involved in the formation of chlorophyll, proteins, and DNA, all of which are essential for the growth, energy production, and reproduction of the plant. This, in turn, helps the plant grow healthy and resilient.
Question 26 Rapport
The web-feet of frogs and toads is basically for
Détails de la réponse
The **web-feet** of frogs and toads are primarily for **swimming**. Frogs and toads have webbed feet, which means their toes are connected by a thin membrane. This structure acts like a paddle, allowing them to push against water more effectively and move with greater ease and speed when they swim.
**Webbed feet** increase the surface area of their feet, providing more propulsion through the water, much like the way a duck's or other aquatic animal's webbed feet work. While they may also use their feet for other activities like **leaping** and **walking**, the primary adaptation and evolutionary advantage of having webbed feet is to enhance their ability to **swim** efficiently. Swimming is essential for frogs and toads because many of them live near water bodies and often have to escape predators, hunt for food, or move between land and water habitats.
Question 27 Rapport
The total number of ATP produced during glycolysis is
Détails de la réponse
Glycolysis is the process through which one molecule of glucose is broken down into two molecules of pyruvate, and this process occurs in the cytoplasm of the cell. During glycolysis, two different phases are involved: the energy investment phase and the energy payoff phase. Let's break it down:
Energy Investment Phase: At the start of glycolysis, the cell uses 2 ATP molecules. This phase is necessary to modify the glucose molecule and prepare it for the subsequent reactions.
Energy Payoff Phase: As glycolysis continues, 4 ATP molecules are produced. These ATP molecules are formed when certain intermediates donate phosphate groups to ADP (adenosine diphosphate) to form ATP.
Hence, the net gain of ATP during the glycolytic process is calculated by subtracting the ATP used in the Energy Investment phase from those produced in the Energy Payoff phase.
The calculation is as follows:
ATP Produced = 4 molecules
ATP Used = 2 molecules
Net Gain = 4 - 2 = 2 molecules
Therefore, the total number of ATP produced during glycolysis, when considering the net gain, is 2 molecules of ATP.
Question 28 Rapport
If the F1 generation allows for self-pollination, what will be the genotypic ratio of the offspring?
Détails de la réponse
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 29 Rapport
Lamarck's theory of evolution is based on the idea of
Détails de la réponse
Lamarck's theory of evolution is based on the idea of the inheritance of acquired traits. According to Lamarck, organisms can change during their lifetime by using or not using certain parts of their body. For example, he suggested that if a giraffe stretches its neck to reach higher leaves on trees, its neck will become longer. Furthermore, these traits that were acquired during an organism's lifetime could then be passed down to its offspring. Thus, the next generation would inherit the longer neck, leading to a gradual evolution of longer-necked giraffes over generations. This theory was one of the earliest ideas about evolution, although it has since been largely superseded by Darwin's theory of natural selection.
Question 30 Rapport
Which of the following structures enables the exchange of gases in insects?
Détails de la réponse
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.
Question 31 Rapport
The transmission of diseases through contamination of food is an economic importance of
Détails de la réponse
The transmission of diseases through contamination of food is an economic importance primarily related to cockroaches.
Cockroaches are considered pests that thrive in unsanitary environments. They are known to carry various pathogens, such as bacteria, viruses, and parasites, on their bodies and in their droppings. When they come into contact with food, they can contaminate it, leading to foodborne diseases.
This contamination can have several economic impacts:
Therefore, managing and preventing cockroach infestations is crucial to safeguarding public health and protecting economic interests associated with food safety.
Question 32 Rapport
Which of the following factors can lead to overcrowding?
Détails de la réponse
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 33 Rapport
The abiotic factor that affect the population growth of an organism is
Détails de la réponse
The term abiotic factors refers to the non-living components of an environment that can influence the growth and survival of organisms. In the given options, the factor that qualifies as an abiotic factor is rainfall. Abiotic factors are different from biotic factors, which involve living things such as predators, food availability, and diseases.
Explanation:
1. **Rainfall**: This is the only abiotic factor mentioned in the list. Rainfall provides water, which is essential for the survival of most organisms. It affects the availability of water resources, which are crucial for hydration of plants and animals, as well as for maintaining aquatic habitats. The amount, timing, and distribution of rainfall can influence the growth of plant populations, which in turn affects the availability of food and shelter for other organisms.
2. **Predator**: This is not an abiotic factor. Predators are living organisms that can directly influence the population of prey species by hunting and consuming them. This is a biotic interaction.
3. **Food Shortage**: Food availability is related to living organisms and is considered a biotic factor. Food shortage directly affects the survival and reproduction of organisms that depend on that food source.
4. **Disease**: This is again a biotic factor. Diseases are caused by pathogens, which are living organisms such as bacteria, viruses, or fungi, and they can spread among populations, reducing their size and growth.
In summary, rainfall is the abiotic factor from the choices given, and it plays a critical role in the environment by influencing water availability and ecosystem balance.
Question 34 Rapport
How many chromosomes will be present in a gamete if the somatic cell has 8 chromosomes?
Détails de la réponse
In humans and many other organisms, there are two types of cells: **somatic cells** and **gametes**. **Somatic cells** are typical body cells and are **diploid**, meaning they contain two sets of chromosomes—one set from each parent. **Gametes** are reproductive cells (sperm and egg) and are **haploid**, meaning they contain only one set of chromosomes.
In this context, if a **somatic cell** has **8 chromosomes**, it means it is carrying two complete sets of 4 chromosomes each. In order to form a **gamete**, this diploid number must be reduced to a **haploid number** through the process of **meiosis**.
Therefore, the **number of chromosomes** in a **gamete** would be **half** the number of chromosomes in a **somatic cell**. This is because gametes need to have just one set of chromosomes to ensure that when two gametes meet during fertilization, they create a diploid organism.
Thus, if the **somatic cell** has **8 chromosomes**, each **gamete** will have **4 chromosomes**.
Question 35 Rapport
Which of the following plants shows hypogeal germination?
Détails de la réponse
To understand which plants exhibit hypogeal germination, we first need to comprehend what hypogeal germination is. In hypogeal germination, the cotyledons remain below the soil surface after the seed germinates. This occurs because the seedling's epicotyl (the part of the seedling above the cotyledons) elongates, pushing the shoot tip above the ground while the cotyledons stay buried, often serving their purpose as energy reserves.
Let's examine the given options:
From the options provided, both Groundnut and Maize exhibit hypogeal germination. While Groundnut's germination involves the cotyledons staying underground, Maize's germination follows a similar principle with its own adaptations.
Question 36 Rapport
A common component of blood and lymph is
Détails de la réponse
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 37 Rapport
Which of the following is a viral disease?
Détails de la réponse
Out of the diseases listed, Measles is a viral disease. Let me explain this simply:
In summary, Measles is the only viral disease among the options provided, as it is specifically caused by a virus, unlike the others, which are caused by bacteria.
Question 38 Rapport
The oxygen transported to all parts of the body during blood circulation is used for the
Détails de la réponse
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 39 Rapport
Infectious diseases are caused by
Détails de la réponse
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 40 Rapport
The number of vertebrae in the human vertebral column is
Détails de la réponse
The human vertebral column, also known as the spine or backbone, consists of a series of bones called vertebrae. These vertebrae are stacked on top of each other and are categorized into different regions. There are a total of 33 vertebrae in the human vertebral column.
Here's a simple breakdown:
Therefore, when you add up these vertebrae (7 cervical + 12 thoracic + 5 lumbar + 5 sacral + 4 coccygeal), you get a total of 33 vertebrae in the human vertebral column. It's important to note that while the sacral and coccygeal vertebrae are often fused together, they are still counted separately when totaling the number of vertebrae.
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