JAMB UTME - Biology - 2019
Pergunta 1 Relatório
One important characteristics of green plant is that they
Detalhes da Resposta
Green plants are autotropic. This means that they are able to produce their own food through a process called photosynthesis. During photosynthesis, plants use energy from sunlight, carbon dioxide from the air, and water from the soil to produce glucose, which is their source of energy. This characteristic sets plants apart from animals and other organisms that are heterotrophic and rely on other organisms for their food.
Pergunta 2 Relatório
A population is best described as
Detalhes da Resposta
A population is best described as a group of individuals of the same species that live together in the same area and can potentially interact with each other. For example, a population of deer living in a forest would consist of all the individual deer of the same species that live in that forest and are able to mate with each other. This definition excludes which includes plants and animals of different species living together, and which includes different species of wild animals. includes only a specific subset of organisms, and is not a comprehensive definition of a population.
Pergunta 3 Relatório
Rabbits cannot survive in an aquatic habitat because they have
Detalhes da Resposta
Rabbits cannot survive in an aquatic habitat because they have no gills. Gills are specialized organs that allow fish and other aquatic animals to extract oxygen from water. Without gills, rabbits would be unable to breathe underwater and would quickly suffocate. Additionally, rabbits are not built for an aquatic lifestyle. They have short legs and are not adapted for swimming or propelling themselves through water. While they may be able to paddle around for a short period of time, they would eventually tire and be unable to keep themselves afloat. This is why rabbits are best suited to a terrestrial habitat where they can easily breathe and move around.
Pergunta 4 Relatório
Which of the following is considered to be the first product of Photosynthesis?
Detalhes da Resposta
Starch is the main and first product formed during photosynthesis because the simple sugar formed is partly used by the plant and excess of it is converted into starch immediately for storage and the starch is transported to other parts of the plant through the phloem vessels for storage.
Pergunta 5 Relatório
A virus can sometimes be regarded as a living organism because it
Detalhes da Resposta
A virus is often considered a living organism because it can reproduce inside living cells. This means that it uses the machinery of the host cell to make copies of itself. However, viruses do not have the ability to carry out all the processes of life, such as producing energy and growing on their own. They rely on the host cell to perform these functions for them. So, whether a virus is considered living or not is still a matter of debate among scientists.
Pergunta 6 Relatório
Which of the following is not a transmitable character in plants
Detalhes da Resposta
Haemophilia is not a transmittable character in plants. Haemophilia is a genetic disorder that affects blood clotting in humans and other animals, and it has no relevance to plants. On the other hand, the habit of growth, resistance to environmental factors, and lifespan are all heritable traits that can be transmitted from parent plants to their offspring through genetic material such as DNA. The habit of growth refers to the overall shape and size of the plant, including whether it is a tree, shrub, or herb. Resistance to environmental factors refers to a plant's ability to survive in adverse conditions such as drought, high salinity, or extreme temperatures. Lifespan refers to the length of time that a plant can live and reproduce. All of these traits are important for plant survival and are determined by genetic factors that can be passed down from one generation to the next.
Pergunta 7 Relatório
The part labeled III in the above diagram is
Detalhes da Resposta
The part labeled III in the diagram is Hyphae. Hyphae are thread-like structures that form the main body of a fungus. They grow in a network called mycelium, which is made up of many hyphae. Hyphae are responsible for absorbing nutrients and water from the environment and transporting them to the rest of the fungus. They also play a role in the reproduction of the fungus by producing spores. Hyphae can vary in size and shape, but they are typically very thin and can grow very long, allowing the fungus to spread over a large area.
Pergunta 8 Relatório
In natural selection, Darwin proposed that evolution occurred because of the following conditions except
Detalhes da Resposta
The exception to Darwin's proposed conditions for natural selection is "food and other needs are abundant." In Darwin's theory of evolution by natural selection, he proposed that nature selects those organisms that are best adapted to their environment, and those that are not well-adapted will not survive and reproduce. This selection process occurs because resources such as food and other necessities are limited, and only those that are able to obtain these resources will survive and reproduce. If resources were abundant, there would be no need for competition, and selection would not occur.
Pergunta 9 Relatório
Which of the following statement is correct about Southern Guinea Savanna in Nigeria
Detalhes da Resposta
Southern Guinea Savanna is the largest of all biotic community in Nigeria found in Oyo, Osun, Ekiti Status etc.
Pergunta 10 Relatório
The study which involves the inter-relationship between groups of organisms or species of organisms living together in an area is
Detalhes da Resposta
The study which involves the inter-relationship between groups of organisms or species of organisms living together in an area is called synecology. Synecology is a branch of ecology that examines the interactions and relationships between different species in a given ecosystem or community. It considers the biotic and abiotic factors that affect the survival and growth of populations and how they interact with one another. This study helps us to understand the complex network of relationships between different species and how they are dependent on one another for their survival. It is important for understanding the dynamics of ecosystems and how they may change over time due to human or natural factors.
Pergunta 11 Relatório
Albinism is an expression of trait controlled by
Detalhes da Resposta
Albinism is an expression of a trait controlled by recessive genes. Albinism is a genetic condition that results in a lack of melanin, a pigment that provides color to the skin, hair, and eyes. The condition is caused by mutations in genes that produce or distribute melanin. In order for an individual to have albinism, they must inherit two copies of the mutated gene, one from each parent. If an individual inherits one normal gene and one mutated gene, they will not have albinism, but they will be a carrier of the condition and can pass it on to their offspring. This is why albinism is considered a recessive trait, meaning it is only expressed when two copies of the mutated gene are present. So, in summary, albinism is an expression of a trait controlled by recessive genes, meaning that it is caused by mutations in genes that produce or distribute melanin, and it is only expressed when two copies of the mutated gene are present.
Pergunta 12 Relatório
Which of the following describes an example of fertilization in higher organisms?
Detalhes da Resposta
The correct answer is: "Fusion of sperm and egg nuclei" Fertilization is the process in which a male gamete (sperm) combines with a female gamete (egg or ovum) to form a zygote, which is the first cell of the new organism. In higher organisms, including humans, fertilization occurs when a sperm cell penetrates the outer membrane of the egg cell and fuses with the egg's nucleus, resulting in the fusion of genetic material from both the sperm and the egg. The other options listed are not examples of fertilization. - Pollen grain landing on a sticky stigma is a process called pollination, which occurs in plants. Pollen grains contain male gametes, but pollination is not the same as fertilization, as the male and female gametes do not actually combine until after the pollen tube grows down into the ovule and the sperm cells are released to fuse with the egg. - Ejaculation of the egg and pollen grain is not a biological process that occurs in any known organism. - Ejaculation of sperm into the female body is the first step in the process of fertilization, but it is not fertilization itself. The sperm must still reach and penetrate the egg to complete the process of fertilization.
Pergunta 13 Relatório
Possession of thin membrane enables a tapeworm to
Detalhes da Resposta
The tapeworm possesses a thin membrane mostly because of it absorption of digested food from the intestine of the host.
Pergunta 14 Relatório
The possession of chloroplast in Euglena virids enables it to
Detalhes da Resposta
The possession of chloroplast in Euglena viridis enables it to carry out photosynthesis. Photosynthesis is the process by which green plants and algae use sunlight to synthesize food (glucose) from carbon dioxide and water. Chloroplasts are organelles found in the cells of green plants and algae that contain the pigment chlorophyll, which absorbs sunlight and is essential for photosynthesis. Euglena viridis is a unicellular organism that possesses chloroplasts, which enables it to harness sunlight to produce its own food through photosynthesis. Therefore, the answer is that the possession of chloroplast in Euglena viridis enables it to carry out photosynthesis.
Pergunta 15 Relatório
Which of the blood corpusles are irregular and amoeloid in shape
Detalhes da Resposta
The irregular and amoeboid-shaped blood corpuscles are called "Leucocytes," which are also known as white blood cells. Leucocytes are an essential part of our immune system, and their main function is to protect the body against infections, diseases, and foreign invaders. Unlike erythrocytes (red blood cells) and thrombocytes (platelets), which have a uniform, round shape, leucocytes are irregular and amoeboid in shape, allowing them to move freely throughout the body and easily pass through the walls of blood vessels to reach the site of infection or injury. Leucocytes are classified into two main types: granulocytes and agranulocytes, based on the presence or absence of granules in their cytoplasm. Granulocytes have granules in their cytoplasm and include neutrophils, eosinophils, and basophils, while agranulocytes lack granules and include lymphocytes and monocytes. Overall, leucocytes play a critical role in our immune system and help keep us healthy by identifying and fighting off pathogens and foreign invaders.
Pergunta 16 Relatório
Which of the following is the effect of using artificial pollination in plant breeding?
Detalhes da Resposta
The effect of using artificial pollination in plant breeding is "Improvement of the variety of crops". Artificial pollination is the process of manually transferring pollen from one flower to another to fertilize it, with the goal of producing hybrid plants with desirable traits. This allows plant breeders to combine traits from two different plants to create a new variety with improved qualities such as increased yield, disease resistance, and improved flavor. By using artificial pollination, plant breeders can control the genetics of the resulting offspring, leading to the creation of new crop varieties with improved traits. This can help to increase food production and improve the quality of crops, making them more resilient and better suited for different growing conditions.
Pergunta 17 Relatório
Which of the following juices contains the enzyme ptyalin?
Detalhes da Resposta
The juice that contains the enzyme ptyalin is saliva. Ptyalin, also known as salivary amylase, is an enzyme that breaks down complex carbohydrates into simple sugars. It is produced by the salivary glands and released into the mouth when we eat. Ptyalin begins the process of digestion in the mouth, breaking down starchy foods such as bread and potatoes into smaller, more easily digestible molecules. Gastric juice is produced by the stomach and contains hydrochloric acid and enzymes that help break down proteins. Succus is not a specific type of juice. It can refer to any juice that is extracted from a plant or fruit. Pancreatic juice is produced by the pancreas and contains enzymes that help break down proteins, carbohydrates, and fats in the small intestine. So, the correct answer is saliva.
Pergunta 18 Relatório
Thunderstorm can be beneficial to plants because it
Detalhes da Resposta
Thunderstorms can be beneficial to plants because they add nitrogen to the soil. Lightning is an electrical discharge that can break apart nitrogen molecules in the air, and the resulting nitrogen compounds can fall to the ground in rainwater. Plants need nitrogen to grow, and thunderstorms can provide a natural source of this essential nutrient. However, it's important to note that while thunderstorms can bring benefits, they can also bring harm in the form of lightning strikes and flooding, so it's important to take necessary precautions to protect yourself and your property during severe weather.
Pergunta 19 Relatório
Which of the following will have the least effect on the rate of change of the numbers in a population
Detalhes da Resposta
The food supply will have the least effect on the rate of change of the numbers in a population. While food supply can impact the growth and survival of a population, it is less likely to cause rapid changes in population size compared to other factors such as disease, predation, and mutation. Disease, predation, and mutation can all have significant impacts on a population by affecting the survival and reproductive success of individuals, leading to changes in the overall population size. For example, a disease outbreak can reduce the number of individuals in a population, while predation can limit the growth of a population by preying on individuals. Mutations can also impact the population by changing the genetic makeup of the population and altering its ability to survive and reproduce. In conclusion, while food supply is important for maintaining a stable population, it is less likely to cause rapid changes in population size compared to other factors such as disease, predation, and mutation.
Pergunta 20 Relatório
The change in the genetic make up of an organism resulting in an inheritable characteristics which is new is
Detalhes da Resposta
Mutation is the change in the genetic make up of an organism, which results in a new inheritable characteristic. Simply put, a mutation is a change in an organism's DNA that can be passed down to future generations. Mutations can happen naturally or can be caused by environmental factors such as exposure to radiation or chemicals. These changes can result in a variety of effects, from a simple alteration in an organism's appearance to a serious medical condition.
Pergunta 21 Relatório
Which of the following organs can be considered vestigial in humans but functional in other mammals
Detalhes da Resposta
The appendix is considered to be vestigial in humans but functional in other mammals. In humans, the appendix serves no known purpose and can become inflamed and cause pain (appendicitis), which often requires surgical removal. However, in other mammals such as cows and horses, the appendix serves as a fermentation chamber where beneficial bacteria can break down tough plant fibers into simpler sugars that can be easily absorbed. This process is important for their digestion and survival.
Pergunta 22 Relatório
Which of the following substances pass through the root cell membrane by osmosis?
Detalhes da Resposta
Water passes through the root cell membrane by osmosis. Osmosis is the movement of water molecules from an area of higher concentration to an area of lower concentration across a semi-permeable membrane. In plants, water is absorbed through the root hairs of the plant and moves into the root cells. The root cell membrane is selectively permeable, meaning that it allows certain molecules to pass through while blocking others. Water molecules are small enough to pass through the membrane, but larger molecules like cell sap, carbon dioxide, and oxygen cannot pass through by osmosis. Therefore, the correct answer is water.
Pergunta 23 Relatório
Which of the following is an example of discontinous variatio?
Detalhes da Resposta
Discontinuous variation is the differences of variations in behaviour by which organisms can be grouped into 2 or more classes within a population without any intermediates among them e.g Behaviour, ability to roll tongue.
Pergunta 24 Relatório
The glomerular filtrate contains the following except
Detalhes da Resposta
The glomerular filtrate contains all of the substances listed except blood corpuscles. The glomerular filtrate is a fluid that is filtered from the blood in the kidneys through a specialized structure called the glomerulus. This fluid contains water, small molecules like glucose, amino acids, and urea, and ions like sodium, potassium, and chloride. Blood corpuscles, also known as blood cells, are not normally present in the glomerular filtrate because they are too large to pass through the small pores in the glomerular capillaries. Blood cells are important components of blood that help to transport oxygen, fight infection, and support the body's immune system. The glomerular filtrate is a crucial step in the process of urine formation, as it allows for the selective reabsorption of important substances like water and glucose while removing waste products like urea. The remaining fluid is then processed by the kidney tubules to form urine, which is eventually excreted from the body. It is important to note that the composition of the glomerular filtrate can vary depending on a person's diet, hydration status, and overall health, and that disorders of the kidneys can affect the ability of the kidneys to filter and process this fluid correctly.
Pergunta 25 Relatório
Inheritable character/features possessed by an organism can be referred to as
Detalhes da Resposta
Genes are the inheritable character/features possessed by an organism. They are the basic unit of heredity and carry information from one generation to the next. A gene is a segment of DNA that contains the instructions for making a specific protein. The proteins made by genes control the growth, development, and function of our bodies. Each of us has many thousands of genes, which together determine our traits and characteristics. So, genes are the underlying cause of the traits and characteristics that are passed down from parent to offspring.
Pergunta 26 Relatório
Which of the following organs can be considered vestigial in humans but functional in other mammals
Detalhes da Resposta
The appendix can be considered vestigial in humans but functional in other mammals. The appendix is a small pouch-like organ attached to the large intestine. In many other mammals, the appendix serves as a functional part of the digestive system, helping to break down cellulose and other tough plant materials that are difficult to digest. However, in humans, the appendix is considered vestigial, which means it is a structure that has lost its original function over the course of evolution. While the appendix may have had a digestive function in our distant ancestors, today it appears to have no essential role in our digestive system. However, the appendix does contain lymphoid tissue, which plays a role in the immune system, particularly during early childhood. This suggests that the appendix may still have some function in the immune system, though its exact role is not yet fully understood. In rare cases, the appendix can become inflamed and infected, leading to a condition called appendicitis. If left untreated, appendicitis can be life-threatening. In such cases, the appendix is removed through surgery, and the individual can still live a healthy life without any ill effects. In summary, the appendix is considered vestigial in humans, meaning it has lost its original function in the course of evolution. While it may still have some minor immune-related functions, it is not considered essential for human health, and in some cases, it can even be harmful if it becomes infected.
Pergunta 27 Relatório
The following processes are involved during expiration in man except
Detalhes da Resposta
The process involved during expiration in humans that is not accurate is "The thoracic cavity first increases in volume." During expiration, the diaphragm, which is a muscle located at the bottom of the thoracic cavity, relaxes and moves upwards, decreasing the volume of the thoracic cavity. At the same time, the intercostal muscles, located between the ribs, also relax, and the ribs move downward and inward, causing the chest to decrease in size. Additionally, the sternum moves outward, not inward, during expiration. These combined actions increase the pressure within the thoracic cavity, forcing air out of the lungs. Overall, expiration is a passive process that does not require the use of energy, and it is the opposite of inspiration, which is the process of taking air into the lungs.
Pergunta 28 Relatório
The type of nutrition shown by spirogyra is
Detalhes da Resposta
The type of nutrition shown by Spirogyra is holophytic. Holophytic nutrition, also known as autotrophic nutrition, is a type of nutrition where an organism synthesizes its own food from inorganic substances, such as carbon dioxide and water, using energy from the sun through the process of photosynthesis. Spirogyra is a type of filamentous green algae that belongs to the group of plants that can carry out photosynthesis to produce their own food. These plants contain chloroplasts, which are specialized organelles that contain chlorophyll, the pigment that absorbs light energy from the sun. During photosynthesis, Spirogyra takes in carbon dioxide and water and uses energy from sunlight to produce glucose and oxygen. This process is essential for the growth and survival of Spirogyra and other autotrophic organisms.
Pergunta 29 Relatório
The specific portion of a habitat which is occupied by a particular species is referred to as
Detalhes da Resposta
The specific portion of a habitat that is occupied by a particular species is referred to as its "Ecological Niche". An ecological niche refers to the role and position a species has in its environment, including its relationships with other species, the way it obtains food and resources, and the physical conditions it requires to survive. Essentially, it's the species' unique way of life and how it fits into its habitat. For example, a bird species might have a specific ecological niche as a seed-eater, and it might occupy a certain area of a forest where seeds are abundant. Another species might occupy a different niche as a predator, hunting for insects in a different part of the forest. These two species have their own unique ecological niches and do not overlap in the way they interact with their environment.
Pergunta 30 Relatório
Which of the following is a nitrifying bacterium?
Detalhes da Resposta
A nitrifying bacterium is a type of bacterium that is capable of converting nitrogen compounds from one form to another. Out of the options you provided, the correct nitrifying bacterium is Nitrobacter. Nitrobacter is a genus of bacteria that oxidizes nitrite (NO2-) to nitrate (NO3-). This process is called nitrification and is an important part of the nitrogen cycle in the environment.
Pergunta 31 Relatório
The period of inactivity seen in some animals during long period of heat or drought is
Detalhes da Resposta
The period of inactivity seen in some animals during long periods of heat or drought is called aestivation. Aestivation is a type of dormancy, similar to hibernation, but it occurs in response to hot or dry conditions, while hibernation occurs in response to cold or food scarcity. During aestivation, animals reduce their metabolic activity and enter a state of deep sleep to conserve energy and water until more favorable conditions return. This strategy helps them survive harsh environmental conditions and avoid dehydration, which can be deadly in hot and dry environments. Some animals that undergo aestivation include certain snails, frogs, and turtles, as well as some mammals like the marsupial mouse and the fat-tailed dwarf lemur.
Pergunta 32 Relatório
Which of the following substances has the highest amount of energy in joules per unit weight?
Detalhes da Resposta
Fats have the highest amount of energy in joules per unit weight compared to carbohydrates, proteins, and vitamins. This is because fats contain more carbon and hydrogen atoms than carbohydrates and proteins, and these atoms have a higher potential to release energy when they are broken down and burned during cellular respiration. One gram of fat provides about 9 calories (37.7 kJ) of energy, while one gram of carbohydrates or proteins provides only about 4 calories (16.7 kJ) of energy. Vitamins, on the other hand, are not significant sources of energy and play important roles in supporting various metabolic processes in the body. To put it simply, fats contain more energy per unit weight than other substances because they are made up of more energy-rich carbon and hydrogen atoms.
Pergunta 33 Relatório
The organism above can be found in
Detalhes da Resposta
It is found in moist environment because of its adaptive features.
Pergunta 34 Relatório
One of the following is a process of transmission of hereditary characteristics by chromosomes
Detalhes da Resposta
Dictating the formation of a protein by a gene in a chromosome is a process of transmitting hereditary characteristics
Pergunta 35 Relatório
Ecology is best defined as the study of
Detalhes da Resposta
Ecology is best defined as the study of the inter-relationship between living organisms and the environment. It is the study of how organisms interact with each other and their surroundings, including both living and non-living components of the environment. Ecology is a broad field that encompasses many different areas of study, including the study of populations, communities, ecosystems, and biomes. Ecologists examine the ways in which living organisms interact with each other and with their physical and chemical environment, as well as the ways in which human activities can impact these interactions. By understanding the relationships between organisms and their environment, ecologists can develop strategies for conservation, management, and restoration of ecosystems. For example, ecologists can study the impacts of climate change on ecosystems, and develop plans to mitigate these impacts and help protect the biodiversity of our planet. So, the correct answer is "the inter-relationship between living organisms and the environment."
Pergunta 36 Relatório
The male sex cells also called gametes are produced in the testes by a process called
Detalhes da Resposta
The male sex cells, also called gametes, are produced in the testes by a process called Spermatogenesis. Spermatogenesis is the process by which sperm cells are produced and mature. It begins in puberty and continues throughout a man's life. During spermatogenesis, the cells in the testes divide and differentiate into sperm cells, which are then stored in the epididymis until they are ready to be ejaculated. Sperm cells are important for fertilization and are necessary for sexual reproduction.
Pergunta 37 Relatório
Reading the verdict of a case by a magistrate is an example of
Detalhes da Resposta
Reading the verdict of a case by a magistrate is an example of a voluntary action. Voluntary actions are those actions that require conscious effort and decision-making. In this case, the magistrate has to actively choose to read the verdict and make a conscious effort to understand and communicate the decision to those involved in the case. It is not a reflex action, as it does not occur automatically in response to a stimulus. It is also not an instinct or a conditioned reflex, as it is not a natural behavior or a learned response to a particular situation.
Pergunta 38 Relatório
The movement of blood between the heart and all other parts of the body beside the lungs is
Detalhes da Resposta
The movement of blood between the heart and all other parts of the body beside the lungs is called systemic circulation. In the systemic circulation, oxygenated blood flows from the heart to the body's organs and tissues, providing them with the oxygen and nutrients they need to function properly. After the oxygen has been used up by the cells, the blood carrying carbon dioxide and other waste products is then transported back to the heart to be pumped to the lungs, where it will be oxygenated again in the pulmonary circulation. The systemic circulation is a critical part of the body's overall circulatory system, which also includes the pulmonary circulation. Together, these two systems help to ensure that every part of the body has a constant supply of oxygen and nutrients and that waste products are efficiently removed from the body.
Pergunta 39 Relatório
What type of vertebrate assists in breathing alongside with the ribs?
Detalhes da Resposta
The type of vertebrate that assists in breathing alongside the ribs are thoracic vertebrates. The thoracic region of the spine is located in the upper and middle back, and it is the region that supports the ribcage. In thoracic vertebrates, the ribs are attached to the vertebrae and to the sternum, or breastbone, forming a protective cage around the heart and lungs. During breathing, the diaphragm muscle contracts and flattens, which increases the volume of the chest cavity and draws air into the lungs. At the same time, the ribcage expands, which further increases the volume of the chest cavity and helps to pull air into the lungs. The ribs play a crucial role in this process by expanding and contracting with each breath. In addition to the diaphragm muscle, the muscles between the ribs, called intercostal muscles, also contract and relax to help move air in and out of the lungs. Sacral, caudal, and lumbar vertebrates do not have the same type of ribcage as thoracic vertebrates and therefore do not rely on the expansion and contraction of ribs for breathing. Instead, these vertebrates have other adaptations that allow them to breathe efficiently in their respective environments. For example, fish extract oxygen from water through their gills, while reptiles and some mammals, such as whales and dolphins, can hold their breath for long periods of time underwater.
Pergunta 40 Relatório
Which of the following pairs of scientists discovered the Rhesis factor in human blood?
Detalhes da Resposta
The pair of scientists who discovered the Rhesis factor in human blood is Landsteiner and Levine. Karl Landsteiner was an Austrian biologist and physician who is best known for his discovery of the ABO blood group system. In 1940, he and his colleague Alexander S. Wiener discovered the Rh factor, which is a protein that is found on the surface of red blood cells in some individuals and can cause an immune response in others. This discovery was a significant breakthrough in the field of blood transfusion and helped to reduce the risk of transfusion reactions in patients. Levine is likely a reference to Philip Levine, an American immunologist who worked with Landsteiner and Wiener at the Rockefeller Institute for Medical Research in New York. Levine played a key role in the discovery of the Rh factor, conducting many of the experiments that helped to confirm the existence of the protein. Neither Hooke nor Darwin were involved in the discovery of the Rh factor in human blood. Robert Hooke was a 17th-century English scientist who made important contributions to the fields of microscopy, physics, and biology, while Charles Darwin was a 19th-century British naturalist who is best known for his theory of evolution by natural selection. In summary, the correct answer is Landsteiner and Levine, as they were the scientists who discovered the Rh factor in human blood.
