MDCAT Biology MCQs Chapter Wise.
Biological molecules are complex molecules that are essential for life processes in living organisms. These molecules are made up of atoms of different elements such as carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur and phosphorus. Biological molecules are involved in a wide range of functions in living organisms, such as energy storage, cell signaling, structural support, and enzymatic reactions.
Enzymes are the most important group of proteins which are biologically active. They tremendously increase the efficiency of a biochemical reaction and are specific for each type of reaction. Without these enzymes the reaction would proceed at a very slow speed making life impossible.
Enzymes are composed of hundreds of amino acids joined together and coiled upon themselves to form a globular structure. The catalytic activity is restricted to a small portion of the structure known as the active site. The reactant called substrate is attached to the active site consisting of only a few amino acids, while rest of the bulk of the amino acids maintains the globular structure of the enzyme.
The Cells | MDCAT Biology MCQs
Cell biology is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. Cell biology is the study of structural and functional units of cells.
Variety of Life
The variety of life refers to the diverse range of living organisms found on Earth. Living organisms can be classified into different groups based on their similarities and differences in physical and biological characteristics. These characteristics can be observed and studied in order to create a classification system.
The most widely used classification system is the Linnaean classification system, which categorizes living organisms into a hierarchical system based on shared characteristics. This system consists of seven major taxonomic levels, from largest to smallest: Kingdom, Phylum, Class, Order, Family, Genus, and Species.
The classification system is based on the principle of evolution, which suggests that organisms that are more closely related have more similar characteristics and a more recent common ancestor. Therefore, organisms that share a common ancestor are grouped together in the same taxonomic level, while those that have different ancestors are classified into different levels.
Kingdom of Prokaryotes
Prokaryotes are single-celled organisms that lack a nucleus and other membrane-bound organelles. They are classified into two domains, Archaea and Bacteria. Both domains consist of organisms with similar cell structures and are collectively known as prokaryotes.
In the Linnaean classification system, prokaryotes are typically classified into the Kingdom Monera, which is no longer considered valid. Monera was once used to describe all single-celled organisms, including bacteria and archaea, that lack a membrane-bound nucleus. However, this classification was found to be inaccurate as it grouped together organisms that were not closely related.
Today, prokaryotes are generally classified based on their genetic and biochemical characteristics, rather than using the traditional Linnaean classification system. The two domains of prokaryotes, Archaea and Bacteria, are classified into multiple phyla based on their unique characteristics, such as their cell walls, metabolic processes, and DNA sequences.
Archaea is further classified into phyla such as Euryarchaeota, Crenarchaeota, and Thaumarchaeota, while Bacteria is classified into phyla such as Actinobacteria, Proteobacteria, and Cyanobacteria. Each phylum contains multiple classes, orders, families, genera, and species.
Kingdom Protista | MDCAT Biology MCQs
Kingdom Protista is a diverse group of eukaryotic organisms that are primarily unicellular or colonial in nature, and have diverse characteristics and modes of nutrition. This kingdom was created to group together all eukaryotic organisms that did not fit into the other established kingdoms, such as plants, animals, or fungi.
Protists are found in a variety of habitats, including freshwater, marine environments, and soil. They can be classified into several different groups based on their morphology, mode of nutrition, and other characteristics.
Some protists are photosynthetic, such as algae, and are important producers in aquatic ecosystems. Others are heterotrophic, and obtain nutrients by absorbing organic compounds from their environment or consuming other organisms.
Protists can also reproduce in different ways. Some reproduce asexually by mitosis or binary fission, while others undergo sexual reproduction through the fusion of gametes.
Examples of protists include diatoms, which are unicellular photosynthetic algae that are a major component of marine phytoplankton, and amoebas, which are unicellular heterotrophic organisms that move and capture their prey by extending and retracting pseudopodia.
Kingdom of Fungi
The Kingdom Fungi is a diverse group of eukaryotic organisms that are found in almost every ecosystem on Earth. Fungi are characterized by their cell walls, which are made of chitin, and their mode of nutrition, which is typically heterotrophic and involves the absorption of nutrients from their environment.
Fungi can be found in a wide variety of shapes and sizes, from single-celled yeasts to large, multicellular mushrooms. They are classified into several different phyla based on their morphology and reproductive strategies.
Some fungi are decomposers and play an important role in breaking down dead organic matter and recycling nutrients in ecosystems. Others form mutualistic relationships with other organisms, such as mycorrhizal fungi, which form symbiotic relationships with plant roots and help them absorb nutrients from the soil.
Fungi are also economically important, as they are used in the production of food, such as bread and cheese, and in the production of antibiotics and other medicines.
photosynthetic and typically have cell walls made of cellulose. Plants are incredibly diverse and range in size from tiny mosses to towering trees.
Plants are divided into several different groups based on their characteristics, such as their seed structure, vascular system, and flower morphology. Some common groups of plants include ferns, conifers, and flowering plants.
Plants play a critical role in ecosystems, as they are primary producers that convert energy from the sun into organic matter through the process of photosynthesis. They also play a role in regulating the Earth’s climate, as they absorb carbon dioxide from the atmosphere during photosynthesis.
Kingdom Animalia is a diverse group of eukaryotic, multicellular organisms that are characterized by their ability to move, their lack of cell walls, and their heterotrophic mode of nutrition. Animals range in size from tiny insects to large whales, and exhibit an incredible range of morphological, physiological, and behavioral adaptations.
Animals are classified into several different groups based on their characteristics, such as their body plan, the presence or absence of a backbone, and their evolutionary relationships. Some common groups of animals include insects, fish, birds, and mammals.
Animals play a critical role in ecosystems, serving as both predators and prey and influencing the distribution and abundance of other organisms. They are also important to human societies, providing food, fiber, and other resources, as well as serving as companions and sources of inspiration and wonder.
Animal behavior, physiology, and anatomy have been the subjects of intense scientific investigation for centuries, and have led to many important discoveries and advances in medicine, agriculture, and other fields.
Bioenergetics refers to the study of how living organisms acquire, transform, store, and use energy. The primary source of energy for most living organisms is the sun, which is captured through photosynthesis by plants and other photosynthetic organisms.
Energy is then transferred through the food chain as organisms consume other organisms or their byproducts. The process of breaking down food molecules to release energy is known as cellular respiration, which takes place in the mitochondria of cells.
Bioenergetics involves studying the various pathways and mechanisms by which energy is acquired, transformed, stored, and used by living organisms. This includes the study of metabolic pathways, such as glycolysis, the Krebs cycle, and oxidative phosphorylation, which are involved in the breakdown of food molecules to release energy.
Nutrition refers to the process by which living organisms obtain and use food for growth, development, and maintenance of their bodily functions. Nutrients are the substances that are required by the body for various physiological processes, such as energy production, growth, and repair.
There are six major classes of nutrients that are required by the body, including carbohydrates, proteins, fats, vitamins, minerals, and water. Carbohydrates, proteins, and fats are macronutrients that are required in relatively large amounts, while vitamins, minerals, and water are micronutrients that are required in smaller amounts.
Carbohydrates are the primary source of energy for the body, while proteins are important for growth and repair of tissues, and fats are important for energy storage and insulation. Vitamins and minerals are important for various physiological processes, such as immune function, bone health, and regulation of fluid balance. Water is also essential for many bodily functions, including digestion, absorption, and transport of nutrients, as well as regulation of body temperature.
Gaseous exchange is the process by which oxygen is taken in and carbon dioxide is released by living organisms. This process is essential for respiration, which is the process by which energy is produced within cells.
In animals, gaseous exchange takes place in the respiratory system, which is a complex network of organs and tissues that work together to facilitate the exchange of gases between the body and the environment. In humans, the respiratory system includes the nose, mouth, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli.
During gaseous exchange, oxygen is taken in through the respiratory system and transported to the cells where it is used to produce energy through cellular respiration. Carbon dioxide, which is a waste product of cellular respiration, is transported back to the lungs through the bloodstream and is then expelled from the body through exhalation.
In plants, gaseous exchange takes place primarily through tiny pores on the leaves and stems called stomata. Carbon dioxide is taken in through the stomata and is used in photosynthesis to produce glucose and oxygen. Oxygen is then released into the environment through the stomata.
Overall, gaseous exchange is a fundamental process for all living organisms, as it is essential for the production of energy and the removal of waste products from the body.
Transport refers to the movement of substances such as nutrients, gases, and waste products within and between cells, tissues, and organs of living organisms. Transport is essential for the proper functioning and survival of living organisms.
In animals, the circulatory system is responsible for the transport of substances such as oxygen, carbon dioxide, nutrients, and waste products throughout the body. The circulatory system consists of the heart, blood vessels (arteries, veins, and capillaries), and blood.
The heart pumps blood throughout the body, delivering oxygen and nutrients to cells and tissues and picking up waste products such as carbon dioxide. Arteries carry oxygen-rich blood away from the heart, while veins carry oxygen-poor blood back to the heart. Capillaries are tiny blood vessels that connect arteries and veins and allow for the exchange of nutrients, gases, and waste products between the blood and surrounding tissues.
In plants, transport occurs through the vascular system, which consists of two types of specialized tissues: xylem and phloem. Xylem transports water and minerals from the roots to the leaves, while phloem transports sugars and other organic compounds from the leaves to other parts of the plant.
Overall, transport is a fundamental process for all living organisms, as it is essential for the proper functioning and survival of cells, tissues, and organs.
In biology, homeostasis is the state of steady internal, physical, chemical, and social conditions maintained by living systems. This is the condition of optimal functioning for the organism and includes many variables, such as body temperature and fluid balance, being kept within certain pre-set limits
Support and Movement
In chapter Support and Movement, we study human skeletal system (skeleton) which is primarily responsible for support and movement.
The organisms with greater sizes need support to keep their body mass as one unit. This is particularly true for the organisms that live on land. We know that movement and locomotion are characteristics of animals. “Movement” is a general term meaning the act of changing place or position by entire body or by its parts. There are two types of movements i.e. movements of body parts and locomotion. Locomotion is the movement of an animal as a whole from one place to another.
Coordination and Control
The tissues and organs in the bodies of multicellular organisms do not work independently of each other. They work together performing their many tasks as the needs of the whole body. This means that these activities are coordinated. Coordination also enables the organism to respond to happenings in the world around it. One familiar example of coordination is the way in which muscles work together during movement. When a boy runs to catch a ball, he uses hundreds of muscles to move his arms, legs and back. His nervous system uses information from his sense organs and coordinates these muscles. Due to this coordination, the muscles contract in the correct sequence, power and length of time. But that is not all. Such activities involve many other kinds of coordination. For example breathing and heartbeat rates are increased blood pressure is adjusted, and extra heat is removed fast from the body.
Reproduction refers to the process by which living organisms produce offspring that inherit their genetic information. Reproduction is essential for the survival of species, as it ensures the continuation of their genetic information and the ability to adapt to changing environmental conditions.
There are two main types of reproduction: sexual reproduction and asexual reproduction.
Sexual reproduction involves the fusion of gametes (sex cells) from two different individuals to produce offspring with a unique combination of genetic information. In most animals, the male produces sperm and the female produces eggs, which are fertilized to form a zygote. The zygote develops into an embryo and eventually into a mature individual.
Asexual reproduction, on the other hand, does not involve the fusion of gametes and produces offspring that are genetically identical to the parent. Asexual reproduction is common in simpler organisms such as bacteria, fungi, and plants, and may involve processes such as binary fission, budding, or fragmentation.
Reproduction is also regulated by various hormones and environmental factors, which can influence the timing and frequency of reproduction. In addition, reproductive strategies may vary between different species and populations depending on factors such as mating behaviors, parental care, and environmental conditions.
Overall, reproduction is a fundamental process for all living organisms, as it ensures the continuation of genetic information and the survival of species.
Growth and Development
Growth and development are two interconnected processes that living organisms undergo throughout their lifespan.
Growth refers to an increase in the size or mass of an organism, which occurs through cell division and cell enlargement. Cell division allows for the production of new cells, while cell enlargement allows for existing cells to increase in size. Growth is an essential process for living organisms as it enables them to reach their full size and potential.
Development, on the other hand, refers to the process by which an organism changes and matures over time. This includes changes in physical appearance, behavior, and function. Development is a complex process that is influenced by genetic and environmental factors, and is usually characterized by a series of distinct stages or milestones.
In animals, development may include processes such as embryonic development, metamorphosis, and puberty. In plants, development may include processes such as seed germination, vegetative growth, and flowering.
Both growth and development are regulated by a complex interplay of genetic, hormonal, and environmental factors.
Chromosomes and DNA
Chromosomes and DNA are two closely related concepts that play a crucial role in the genetic information and inheritance of living organisms.
DNA (deoxyribonucleic acid) is a molecule that carries the genetic information of an organism. It is composed of four nucleotide bases (adenine, guanine, cytosine, and thymine) that are arranged in a specific sequence to form the genetic code. The sequence of nucleotide bases determines the genetic traits and characteristics of an organism.
Chromosomes are structures within cells that contain DNA. In eukaryotic organisms, such as animals and plants, chromosomes are located in the nucleus of the cell. Each chromosome is composed of a long strand of DNA that is tightly coiled and packaged around proteins called histones. The number and size of chromosomes vary between different species, and can be used to identify and classify organisms.
During cell division, chromosomes are replicated and passed on to daughter cells, ensuring that each cell receives a complete set of genetic information. In sexual reproduction, chromosomes from two different individuals combine to form a unique combination of genetic information in the offspring.
Mutations, or changes in the DNA sequence, can occur naturally or as a result of environmental factors such as radiation or chemicals. These mutations can affect the genetic traits and characteristics of an organism, and may have positive, negative, or neutral effects.
Overall, chromosomes and DNA are fundamental components of the genetic information and inheritance of living organisms. They play a critical role in the development, growth, and reproduction of organisms, and are essential for the continuation of species over time.
Variation of Genetics
Genetic variation refers to the differences in the genetic information between individuals within a population or species. These variations arise from differences in the DNA sequence of the genes, which can result in different traits and characteristics.
There are several sources of genetic variation, including:
Mutation: Mutations are changes in the DNA sequence that can occur spontaneously or as a result of exposure to mutagens such as radiation or chemicals. These mutations can lead to changes in the genetic code, resulting in altered traits or new traits.
Genetic recombination: Genetic recombination is the process by which genetic information is exchanged between homologous chromosomes during meiosis. This results in the formation of new combinations of genetic information and can lead to new traits.
Gene flow: Gene flow occurs when individuals migrate between populations and introduce new genetic material to the population. This can increase genetic diversity within a population and may introduce new traits.
Genetic drift: Genetic drift refers to the random fluctuations in allele frequencies within a population. This can occur due to chance events such as genetic bottlenecks or founder effects, and can lead to the loss of genetic variation.
Genetic variation is important for the survival and evolution of species. It allows for adaptation to changing environments and can provide the raw material for natural selection to act upon. Additionally, genetic variation is the basis of genetic diversity, which is essential for the stability and resilience of ecosystems.
Biotechnology is a field of science that uses biological processes, organisms, or systems to develop and produce useful products and technologies. It encompasses a wide range of applications, from the production of pharmaceuticals and biopharmaceuticals to the development of genetically modified crops and the use of gene editing tools.
Some examples of biotechnology applications include:
Medical biotechnology: Medical biotechnology involves the use of biotechnology to develop new treatments for diseases and disorders. This includes the development of new drugs, vaccines, and gene therapies, as well as the use of bioprocessing techniques to produce biologics such as monoclonal antibodies.
Agricultural biotechnology: Agricultural biotechnology involves the use of biotechnology to improve crop yields, reduce crop losses due to pests and diseases, and enhance the nutritional content of crops. This includes the development of genetically modified crops, as well as the use of biostimulants and biocontrol agents to improve plant health.
Industrial biotechnology: Industrial biotechnology involves the use of biotechnology to develop new industrial processes and products, such as biofuels, bioplastics, and enzymes for use in manufacturing.
Environmental biotechnology: Environmental biotechnology involves the use of biotechnology to remediate contaminated sites, monitor environmental pollutants, and develop sustainable solutions for waste management.
Biotechnology relies heavily on genetic engineering techniques such as gene editing, recombinant DNA technology, and synthetic biology. These techniques allow scientists to manipulate the genetic material of organisms to achieve specific outcomes, such as the production of a desired protein or the introduction of a beneficial trait.
Overall, biotechnology is a rapidly growing field with enormous potential to address a wide range of societal challenges and improve human health, agriculture, and the environment. However, it also raises important ethical and safety considerations that must be carefully considered and addressed.
Evolution is the process by which populations of living organisms change over time, typically over many generations. It is driven by natural selection, genetic drift, gene flow, and mutation, and can result in the development of new species.
The basic mechanism of evolution is natural selection, which refers to the process by which certain traits become more or less common in a population based on their effect on an individual’s survival and reproductive success. Individuals with traits that increase their chances of survival and reproduction are more likely to pass those traits on to their offspring, resulting in an increase in the frequency of those traits in the population over time.
Over many generations, natural selection can lead to the development of new species through a process known as speciation. This occurs when populations of the same species become genetically isolated from each other, either geographically or through other means, and evolve separately from each other. Over time, the accumulation of genetic differences can result in populations that are no longer able to interbreed and produce viable offspring.
Evolution is supported by a wide range of evidence, including fossil records, comparative anatomy, embryology, and molecular biology. These lines of evidence demonstrate that living organisms share a common ancestry and have changed over time in response to changing environmental conditions and other factors.
An ecosystem is a community of living organisms (biotic factors) interacting with their physical environment (abiotic factors). It can be as small as a pond or as large as a rainforest. Ecosystems can be divided into two main types: terrestrial (land-based) and aquatic (water-based).
Ecosystems are characterized by complex relationships between living and non-living components, which interact in a complex web of biotic and abiotic factors. These relationships can be categorized into two main types of interactions:
Biotic interactions: This refers to interactions between living organisms within an ecosystem. These interactions can be beneficial (such as mutualism), harmful (such as predation or parasitism), or neutral (such as commensalism).
Abiotic interactions: This refers to interactions between living organisms and their physical environment. These interactions can include factors such as temperature, water availability, and nutrient availability.
All ecosystems have several common components, including:
Producers: These are organisms that produce their own food through photosynthesis or chemosynthesis, such as plants and some bacteria.
Consumers: These are organisms that eat other organisms for food, such as herbivores, carnivores, and omnivores.
Decomposers: These are organisms that break down dead organisms and organic matter, such as fungi and bacteria.
Abiotic factors: These are the non-living components of an ecosystem, including temperature, sunlight, water, air, and soil.
Ecosystems are important for the survival of all living organisms, as they provide essential resources such as food, water, and shelter. They also play a critical role in regulating the Earth’s climate, nutrient cycling, and atmospheric oxygen levels. However, ecosystems are also vulnerable to human activities such as habitat destruction, pollution, and climate change, which can have negative impacts on the health and resilience of ecosystems and the organisms that depend on them.
Some Major Ecosystems
There are many different types of ecosystems around the world, each with unique characteristics and species. Here are some examples of major ecosystems:
Tropical rainforests: These are found near the equator and are characterized by high rainfall and temperatures, and a high diversity of plant and animal species.
Coral reefs: These are found in warm, shallow waters and are characterized by diverse and colorful communities of marine life.
Grasslands: These are found in regions with moderate rainfall and are characterized by tall grasses and grazing animals such as bison and antelope.
Tundra: These are found in cold, Arctic regions and are characterized by low-growing plants and permafrost.
Deserts: These are found in arid regions and are characterized by low rainfall and sparse vegetation, with adaptations such as water storage and nocturnal activity in animals.
Temperate forests: These are found in regions with moderate rainfall and temperatures, and are characterized by deciduous trees and a range of wildlife.
Oceans: These are the largest ecosystem on Earth and are characterized by diverse communities of marine life, from plankton to whales.
Wetlands: These are found in areas with waterlogged soils, such as marshes and swamps, and are characterized by a variety of aquatic and semi-aquatic plants and animals.
Each ecosystem is unique and plays a vital role in the health of the planet, providing important resources and services such as clean water, air, and food. However, many ecosystems are facing threats from human activities such as pollution, climate change, and habitat destruction, highlighting the importance of conservation and sustainable management practices.
Man and his Environment
Man and his environment are closely linked and interdependent. The environment provides the necessary resources for human survival, such as food, water, and shelter, and humans, in turn, have an impact on the environment through their activities.
Human activities such as agriculture, industrialization, and urbanization have led to environmental problems such as pollution, deforestation, and climate change. These problems can have negative impacts on human health, as well as on the health of other species and ecosystems.
Conversely, environmental problems can also have negative impacts on human activities, such as reduced crop yields due to soil degradation or increased health risks due to air pollution.
Sustainable development seeks to balance human needs with environmental protection and conservation, recognizing that the two are interdependent. This approach seeks to promote economic growth and social well-being while protecting the environment and natural resources for future generations.
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