Biology questions and answers: school and DİM level

Question 1

How can I learn biology from zero?

Accepted Answer

Start with the cell, because almost every later topic (genetics, metabolism, body systems) is built on it, then move on to heredity, the organism and its systems, and finally evolution and ecology. Work through your school textbooks in order, learn each new term together with a picture or diagram, and after every chapter close the book and explain the topic out loud in your own words. Twenty to thirty minutes a day works better than one long session a week.

Question 2

How do I prepare for DİM biology?

Accepted Answer

Biology is a block-exam subject in admission group IV, together with chemistry and physics, and it carries a coefficient of 1.5, so it weighs heavily in your total. Build your preparation around DİM's subject programme: after each topic do closed (multiple-choice) tests, and practise the open tasks with coded and written answers separately, because there you have to produce the answer yourself rather than pick it. Check on dim.gov.az each year whether the exam model has changed.

Question 3

How can I memorize biology terms?

Accepted Answer

Learn terms through their roots: many come from Greek and Latin, so knowing that “cyto” means cell, “photo” light and “troph” nourishment unlocks dozens of words at once (photosynthesis, autotroph, heterotroph). Make flashcards with the term on one side and a definition plus a small drawing on the other, and review them the next day, after three days and after a week. In OrujovAI Chat you can ask for flashcards on any chapter and flip through them right in the conversation.

Question 4

Can AI teach me biology?

Accepted Answer

Yes: AI explains a topic as many times and in as many ways as you need, answers follow-up questions, draws simple diagrams and quizzes you at the end. It can get a detail wrong now and then, so double-check key definitions and facts in your textbook, especially for exams. OrujovAI's Live Tutor teaches a topic as a narrated slideshow with a live board and short checks, and its Abituriyent Path takes you through biology's topics in order, with checkpoint quizzes.

Question 5

What is a cell?

Accepted Answer

A cell is the smallest structural and functional unit of life: it takes in substances, uses energy, grows and reproduces. Cell theory says that all living things are made of cells and that every cell comes from another cell by division. Prokaryotic cells (bacteria) have no true nucleus, while eukaryotic cells (plants, animals, fungi) keep their DNA in a nucleus and have membrane-bound organelles.

Question 6

How is a plant cell different from an animal cell?

Accepted Answer

A plant cell has a rigid cell wall made of cellulose, chloroplasts for photosynthesis and usually one large central vacuole, and it stores starch. An animal cell has no cell wall or chloroplasts, its vacuoles are small, it stores glycogen, and it has centrioles, which the cells of higher plants lack. Both have a nucleus, a cell membrane, cytoplasm, mitochondria, ribosomes, endoplasmic reticulum and a Golgi apparatus.

Question 7

What are organelles and what do they do?

Accepted Answer

Organelles are the permanent working parts of a cell, each with its own job. The nucleus stores DNA and controls the cell, mitochondria produce ATP, ribosomes build proteins, the endoplasmic reticulum makes and transports substances, the Golgi apparatus collects and packages them, and lysosomes break down what the cell no longer needs. Plant cells also have chloroplasts for photosynthesis and a large vacuole filled with cell sap, while animal cells have centrioles that take part in cell division.

Question 8

What are DNA and RNA?

Accepted Answer

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are nucleic acids: long chains of nucleotides that store genetic information and put it to use. DNA keeps the hereditary instructions, mostly in the nucleus, as a double helix whose bases pair by complementarity: A with T and G with C. RNA carries out those instructions: messenger RNA copies a gene, transfer RNA brings amino acids, and ribosomal RNA is part of the ribosome.

Question 9

What is the difference between DNA and RNA?

Accepted Answer

DNA is usually double-stranded, its sugar is deoxyribose and its bases are A, T, G and C; RNA is usually single-stranded, contains ribose and has uracil (U) instead of thymine. DNA is a long, stable molecule found mainly in the nucleus (and also in mitochondria and chloroplasts), while RNA molecules are shorter, work in both the nucleus and the cytoplasm, and are broken down quickly. There is a notable exception too: in some viruses, such as the flu virus, the genetic material is RNA rather than DNA.

Question 10

How are proteins synthesized?

Accepted Answer

Protein synthesis happens in two stages. In transcription, a section of DNA (a gene) is copied into messenger RNA in the nucleus; in translation, a ribosome reads the mRNA three nucleotides (one codon) at a time while transfer RNAs bring the matching amino acids and link them into a chain. Translation starts at the start codon AUG and ends at a stop codon (UAA, UAG or UGA), and the finished chain then folds into a working protein.

Question 11

What are enzymes?

Accepted Answer

Enzymes are biological catalysts, almost all of them proteins, that speed up chemical reactions in the cell without being used up. Each enzyme fits its substrate at its active site like a key in a lock, so it speeds up only a specific reaction. Temperature and pH affect them strongly: salivary amylase works best in a neutral environment and pepsin in the acidic stomach, while high heat destroys an enzyme's structure.

Question 12

What is photosynthesis?

Accepted Answer

Photosynthesis is the process in which green plants, algae and some bacteria use light energy to make organic matter (glucose) from carbon dioxide and water, releasing oxygen. In plants it takes place in chloroplasts, where the green pigment chlorophyll absorbs light. The overall equation is 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂, and photosynthesis is the main source of food and atmospheric oxygen on Earth.

Question 13

What are the light and dark stages of photosynthesis?

Accepted Answer

The light stage takes place on the thylakoid membranes of the chloroplast: light splits water (photolysis), oxygen is released as a by-product, and the energy is stored in ATP and NADPH. The dark stage (the light-independent reactions, or Calvin cycle) takes place in the stroma: CO₂ is fixed and glucose is built using that ATP and NADPH. “Dark” only means it doesn't need light directly; in a living plant it runs during the day too.

Question 14

How does cellular respiration work?

Accepted Answer

Cellular respiration releases the energy stored in glucose and saves it as ATP. First, glycolysis in the cytoplasm splits glucose into two molecules of pyruvic acid without oxygen and yields 2 ATP; then, in the mitochondria, the Krebs cycle and the electron transport chain use oxygen to break it down completely to CO₂ and water. School textbooks usually count 38 ATP per glucose in total, while newer estimates are a little lower, around 30–32.

Question 15

What is mitosis?

Accepted Answer

Mitosis is the division of a body (somatic) cell into two daughter cells with the same number of chromosomes and the same genetic information as the parent cell. Before it, during interphase, the DNA is copied; the division itself has four phases: prophase, metaphase, anaphase and telophase. Mitosis is how organisms grow, replace worn-out cells, heal wounds and reproduce asexually.

Question 16

What is meiosis?

Accepted Answer

Meiosis is a cell division that halves the chromosome number: one diploid (2n) cell divides twice in a row and produces four haploid (n) cells. In animals these are gametes (eggs and sperm), in plants spores. During prophase I, homologous chromosomes pair up and swap segments (crossing over), which together with their random distribution makes every gamete genetically unique.

Question 17

What is the difference between mitosis and meiosis?

Accepted Answer

Mitosis has one division and gives two diploid cells identical to the parent; meiosis has two divisions and gives four haploid cells that differ genetically. Mitosis happens in body cells for growth and repair, meiosis in the reproductive organs to form gametes or spores. Only meiosis has pairing of homologous chromosomes and crossing over, which is why it creates variation while mitosis keeps the genotype unchanged.

Question 18

What is genetics?

Accepted Answer

Genetics is the branch of biology that studies heredity and variation: how traits pass from parents to offspring and why offspring differ. Its basic units are genes, sections of DNA that code for a trait, and alleles, the different versions of the same gene. Its foundations were laid by Gregor Mendel's experiments with pea plants in the 1860s.

Question 19

What are Mendel's laws?

Accepted Answer

The first law (uniformity) says that when two pure lines differing in one trait are crossed, all first-generation hybrids (F1) look alike and show the dominant trait. The second law (segregation) says that in F2 the traits split 3:1 by phenotype and 1:2:1 by genotype, because each gamete carries only one allele of a gene. The third law (independent assortment) says that genes for different traits are inherited independently, giving 9:3:3:1 in a dihybrid F2, but only when those genes sit on different chromosomes.

Question 20

How do I solve monohybrid cross problems?

Accepted Answer

First write a key (for example A = yellow seeds, a = green), then the parents' genotypes (P), the gametes each parent can form, and the offspring (F1) in a Punnett square. For Aa × Aa, each parent gives A and a gametes, so you get 1 AA : 2 Aa : 1 aa, which is 3 yellow : 1 green. Finally answer exactly what is asked, a ratio, a percentage or a probability; here, for example, the chance of a green-seeded plant is 1/4, or 25%.

Question 21

How do I solve dihybrid cross problems?

Accepted Answer

Each parent with genotype AaBb forms four kinds of gametes (AB, Ab, aB, ab), so the Punnett square has 4 × 4 = 16 boxes and the classic F2 phenotype ratio is 9:3:3:1. A faster way is to work out each gene separately and multiply: the chance of offspring showing both dominant traits is 3/4 × 3/4 = 9/16, and of being aabb it is 1/4 × 1/4 = 1/16. This shortcut works only when the genes are on different chromosomes; for linked genes you need crossing-over data.

Question 22

How do I solve genetics problems?

Accepted Answer

Most genetics problems follow the same five steps: write the allele key, work out the parents' genotypes (often from the offspring ratio: 3:1 means both parents are heterozygous, 1:1 means a heterozygote was crossed with a homozygous recessive), list the gametes, build the Punnett square and count the ratio the question asks for. Watch for special cases: incomplete dominance gives 1:2:1, sex-linked traits are written on the X chromosome, and blood groups have three alleles. You can photograph a problem in OrujovAI's Solve, get the solution step by step, then test yourself on a similar problem.

Question 23

What are dominant and recessive traits?

Accepted Answer

A dominant trait shows up even with just one copy of its allele (Aa), while a recessive trait appears only when both alleles are recessive (aa). That's why two parents with a dominant trait can have a child with the recessive one if both are heterozygous. Dominant alleles are written with a capital letter and recessive ones with a small letter; in incomplete dominance the heterozygote is in between, as when crossing red and white snapdragons gives pink flowers.

Question 24

What is sex-linked inheritance?

Accepted Answer

Sex-linked inheritance is the inheritance of genes located on the sex chromosomes, usually the X chromosome. Because males (XY) have only one X, a single recessive allele on it shows up in them, which is why hemophilia and color blindness are far more common in men than in women. A carrier woman (XᴴXʰ) passes the allele to half of her sons on average, and a father passes his X only to his daughters, never to his sons.

Question 25

What is a mutation?

Accepted Answer

A mutation is a sudden, heritable change in the genetic material. Gene (point) mutations change a single gene, chromosomal mutations change a chromosome's structure, and genomic mutations change the number of chromosomes, for example an extra chromosome 21 in Down syndrome or polyploidy in plants. Mutations can arise spontaneously, while radiation, certain chemicals and some viruses (mutagens) make them more likely; most are harmful or neutral, but a few are useful and give evolution its raw material.

Question 26

What are heredity and variation?

Accepted Answer

Heredity is the ability of organisms to pass their traits and patterns of development to their offspring; variation is the ability to acquire new traits, which is why individuals of the same species differ. Non-hereditary (modification) variation is caused by the environment within the limits set by the genotype, the reaction norm, such as a suntan or a plant staying small in poor soil. Hereditary variation comes from new combinations of genes in sexual reproduction (combinative) and from mutations (mutational).

Question 27

What is evolution?

Accepted Answer

Evolution is the gradual, historical change of living things over many generations, and today's variety of species is its result. It works on populations rather than individuals: over time, the frequency of different genetic variants in a population changes. Its evidence includes fossils, homologous organs (such as the forelimbs of mammals), similarities between embryos and, most convincingly, comparisons of DNA.

Question 28

What is Darwin's theory of evolution?

Accepted Answer

Charles Darwin set out his theory in “On the Origin of Species” (1859): organisms vary, many of those variations are inherited, and far more offspring are born than can survive. In the resulting struggle for existence, individuals with useful variations survive and reproduce more often (natural selection), so useful traits build up and species slowly change and give rise to new species. The modern synthetic theory joined Darwin's ideas with genetics and treats the population as the unit of evolution.

Question 29

What is natural selection?

Accepted Answer

Natural selection is the survival and reproduction of the individuals best suited to their environment, which leave more offspring and pass their traits on. Textbooks describe three forms: directional (driving) selection shifts a trait one way, stabilizing selection keeps the average form in a steady environment, and disruptive selection favors both extremes. A well-known example is the peppered moth, whose dark form spread in industrial England when soot blackened tree trunks; bacteria becoming resistant to antibiotics is selection too.

Question 30

What is ecology?

Accepted Answer

Ecology is the science of how living organisms relate to each other and to their environment; the term was introduced by Ernst Haeckel in 1866. It studies environmental factors: abiotic (light, temperature, water), biotic (other organisms such as predators, competitors and parasites) and anthropogenic (human activity). Its levels run from a single organism to populations, communities, ecosystems and the whole biosphere.

Question 31

What is a food chain?

Accepted Answer

A food chain shows who eats whom and how energy and matter move through an ecosystem: producers (green plants) → primary consumers (herbivores) → secondary consumers (predators), with decomposers breaking down dead remains at every level. Example: grass → grasshopper → frog → snake → eagle. Only about 10% of the energy passes from one level to the next (the 10% rule), which is why chains rarely have more than four or five links.

Question 32

What is an ecosystem?

Accepted Answer

An ecosystem is a community of living organisms together with its nonliving environment, linked by the flow of energy and the cycling of matter. It can be as small as a pond or as large as a forest or an ocean, and every ecosystem includes producers, consumers and decomposers. Ecosystems stay fairly stable thanks to self-regulation, but deforestation and pollution can upset that balance.

Question 33

What is the biosphere?

Accepted Answer

The biosphere is the layer of the Earth inhabited by living organisms: the lower atmosphere, the whole hydrosphere and the upper part of the lithosphere. The theory of the biosphere was developed by Vladimir Vernadsky, who showed that living matter transforms the planet: the oxygen in the air, the soil and many rocks formed with the help of organisms. The biosphere takes in all of Earth's ecosystems, tied together by global cycles of substances such as carbon, nitrogen and water.

Question 34

What does human anatomy study?

Accepted Answer

Human anatomy studies the structure of the human body: its organs, its tissues and how they are grouped into systems. It goes together with physiology, which studies how those organs work, and hygiene, which is about keeping them healthy. The main systems in a school course are the skeletal and muscular, digestive, respiratory, circulatory, excretory, nervous, endocrine and reproductive systems, plus the skin.

Question 35

How does the digestive system work?

Accepted Answer

Digestion breaks food down into small molecules the body can absorb: proteins into amino acids, carbohydrates into glucose, and fats into glycerol and fatty acids. It starts in the mouth with chewing and saliva, whose amylase begins breaking down starch; in the stomach, hydrochloric acid and pepsin start digesting proteins; in the small intestine, bile from the liver emulsifies fats and pancreatic juice completes digestion. Nutrients are absorbed through the villi of the small intestine, and the large intestine absorbs water and forms stool.

Question 36

How does the respiratory system work?

Accepted Answer

Air passes through the nasal cavity (where it is warmed, moistened and cleaned), the larynx, the trachea and the bronchi into the lungs, ending in tiny air sacs called alveoli. In the alveoli, oxygen diffuses into the blood in the capillaries and carbon dioxide moves out of the blood to be breathed out. Breathing in happens when the diaphragm and the external intercostal muscles contract and enlarge the chest, and breathing is controlled by the respiratory center in the medulla oblongata.

Question 37

How does blood circulation work?

Accepted Answer

Blood moves through two circuits. In the systemic (large) circuit, oxygen-rich blood leaves the left ventricle through the aorta, reaches every organ and returns oxygen-poor through the superior and inferior venae cavae to the right atrium; in the pulmonary (small) circuit, the right ventricle pumps blood through the pulmonary artery to the lungs, and oxygen-rich blood returns through the pulmonary veins to the left atrium. Watch for a classic exam trap: arteries carry blood away from the heart, so the pulmonary artery carries oxygen-poor (venous) blood.

Question 38

What is the structure of the heart?

Accepted Answer

The human heart is a four-chambered muscular organ: two atria on top and two ventricles below, and the left ventricle has the thickest wall because it pumps blood around the whole body. Valves keep blood flowing one way: the bicuspid (mitral) valve on the left and the tricuspid valve on the right between atria and ventricles, and semilunar valves at the exits of the aorta and the pulmonary artery. The heart sits in a sac (the pericardium) and contracts automatically; school textbooks give one cardiac cycle as 0.8 seconds at about 75 beats a minute.

Question 39

How does the nervous system work?

Accepted Answer

The nervous system has a central part, the brain and spinal cord, and a peripheral part, the nerves and ganglia that connect it with the rest of the body. Its cells, neurons, carry electrical impulses along their axons and pass signals to the next cell at synapses using chemical messengers (neurotransmitters). Its basic way of working is the reflex: a receptor detects a stimulus, a sensory neuron carries the signal to the center, and a motor neuron sends a response to a muscle or gland, a pathway called the reflex arc.

Question 40

What is the endocrine system?

Accepted Answer

The endocrine system is made up of ductless glands that release hormones directly into the blood. Its main glands are the pituitary, the thyroid, the adrenal glands, the pancreas (a mixed gland whose islets make insulin and glucagon), the sex glands and the pineal gland, while the hypothalamus links the nervous and endocrine systems. Together with the nervous system it regulates growth, metabolism, development and reproduction.

Question 41

What do hormones do?

Accepted Answer

Hormones are chemical messengers that travel in the blood and change how specific target cells work, even in tiny amounts. For example, insulin lowers blood sugar and glucagon raises it, adrenaline prepares the body for stress, thyroxine (which contains iodine) speeds up metabolism, and growth hormone controls growth. Too much or too little of a hormone causes disease: a lack of insulin leads to diabetes, excess growth hormone in childhood to gigantism, and iodine deficiency can cause goiter.

Question 42

What is immunity?

Accepted Answer

Immunity is the body's ability to protect itself from pathogens and foreign substances (antigens). Non-specific defense includes the skin, mucous membranes and phagocytes that engulf microbes (phagocytosis was discovered by Ilya Mechnikov); specific immunity comes from lymphocytes: B cells make antibodies, while T cells destroy infected cells and direct the immune response. A vaccine creates active artificial immunity by training memory cells, while a therapeutic serum gives ready-made antibodies, which is passive immunity.

Question 43

How are viruses different from bacteria?

Accepted Answer

Bacteria are living prokaryotic cells: they have a cell wall, cytoplasm, ribosomes and DNA without a nucleus, and they reproduce on their own by dividing. Viruses are not cells at all; they consist of a nucleic acid (DNA or RNA) inside a protein coat and can reproduce only inside a host cell. Viruses are also much smaller, most of them visible only under an electron microscope, and antibiotics work against bacteria but not against viruses.

Question 44

Which kingdom do fungi belong to?

Accepted Answer

Fungi form a kingdom of their own, separate from both plants and animals. Like plants they don't move, keep growing throughout life and have a cell wall, but like animals they are heterotrophs, have chitin in their cell walls and store glycogen instead of starch. Their body is a mycelium made of thin threads (hyphae), and they reproduce mostly by spores; yeasts, molds and mushrooms all belong to this kingdom.

Question 45

How are plants classified?

Accepted Answer

Plants are grouped into ranks: kingdom, division, class, order, family, genus and species, and every species has a two-part Latin name. The main groups in a school course are algae (treated as lower plants in many textbooks), mosses, the spore-bearing ferns, horsetails and club mosses, gymnosperms such as pine and spruce, and flowering plants (angiosperms). Flowering plants are divided into monocots, such as wheat and lilies, and dicots, such as roses and beans, by the number of seed leaves, leaf veins and root system.

Question 46

How are animals classified?

Accepted Answer

Animals are classified by kingdom, phylum, class, order, family, genus and species, based on body structure, development and, today, DNA similarity. In a school course they are first split into invertebrates (sponges, cnidarians, flatworms, roundworms, segmented worms, mollusks, arthropods, echinoderms) and chordates. Most chordates are vertebrates, divided into fish (cartilaginous and bony), amphibians, reptiles, birds and mammals.

Question 47

What are the kingdoms of living things?

Accepted Answer

School courses usually name four or five kingdoms: bacteria, fungi, plants, animals and, in many textbooks, protists (single-celled eukaryotes such as amoebas and euglena). Viruses are not placed in any kingdom because they are not cells and are treated as a non-cellular form of life. Modern science also groups all organisms into three domains, Bacteria, Archaea and Eukaryotes, so for exams follow the system your own textbook uses.

Question 48

Where can I find DİM-format biology tests?

Accepted Answer

The main source is DİM itself: it posts the subject programme and the tasks from past exams on dim.gov.az and also publishes biology test collections. Online test sites are useful for volume, but their quality varies, so settle doubtful answers with your textbook. OrujovAI's exam practice builds short DİM-format biology tests at three levels with an explanation for each question; its questions come with answer options, so practise coded and written tasks with DİM's materials.

Question 49

How do I answer open biology questions?

Accepted Answer

In the DİM entrance exam the written biology tasks are built on a situation, so read it carefully, work out exactly what is being asked and answer only that. Use correct biological terms in short, complete sentences, and for a process or a genetics problem show the steps (genotypes, gametes, ratio), not just the final answer. Practise with DİM's published written tasks and check the marking criteria on dim.gov.az, because points are given for specific elements of the answer.

Question 50

How do I learn biology diagrams and drawings?

Accepted Answer

Don't just look at a diagram: redraw it from memory, label it, then compare it with the textbook and fix what you missed. Learn processes (photosynthesis, protein synthesis, circulation) as flowcharts with arrows showing what goes in and what comes out at each step. Covering the labels on a textbook figure and naming the parts out loud is a quick daily self-test before exams.

Question 51

Can AI explain a biology diagram?

Accepted Answer

Yes: photograph a diagram from your textbook and ask the AI to name each part, explain what it does and show how the parts connect. Follow-up questions such as “what happens if this valve doesn't close?” turn a picture into real understanding. AI can misread a blurry photo or an unusual label, so compare its explanation with the caption in your textbook. In OrujovAI Chat you can upload the photo and also ask it to draw a simplified diagram of the process.

Question 52

How do I prepare for a biology olympiad?

Accepted Answer

Olympiad biology goes well beyond the school textbook, so add a university-level general biology book, study plant and animal anatomy, genetics and biochemistry in depth, and solve past olympiad problems against the clock. Practical skills matter too: microscopy, preparing slides and analyzing data are tested, for example, in the practical rounds of the International Biology Olympiad (IBO). For the stages, dates and rules of the national school olympiad in Azerbaijan, follow the official announcements of the Ministry of Science and Education.

Question 53

How do I learn biology in depth to get into medicine?

Accepted Answer

Medicine is in admission group IV, where biology and chemistry carry the most weight, so study the two together rather than as separate subjects. Aim to understand mechanisms rather than memorize lists: how the heart, kidneys and hormones work, how genes and proteins connect, and where biology overlaps with chemistry (enzymes, metabolism). Passing scores for medical specialties change every year, so check the latest figures on dim.gov.az instead of relying on old numbers.

Question 54

How do I use a microscope in a lab class?

Accepted Answer

Carry the microscope with both hands, set the lowest-power objective, place the slide on the stage and adjust the light. Focus first with the coarse knob, then sharpen with the fine knob, and only then switch to a higher objective, using just the fine knob so the lens doesn't hit the slide. Total magnification is the eyepiece times the objective, for example 10 × 40 = 400 times; when making a wet mount (such as onion skin), lower the cover slip at an angle so no air bubbles are trapped.

Question 55

How do I take notes in biology?

Accepted Answer

Write notes in your own words rather than copying sentences: one heading per topic, key terms in bold or color, and a short definition for each. Biology is visual, so add simple labeled drawings and turn comparisons into tables (mitosis vs meiosis, plant vs animal cell, arteries vs veins). End each page with three or four questions to test yourself on later, which turns your notes into a revision tool.

Question 56

How do I review biology topics I keep forgetting?

Accepted Answer

Use spaced repetition: review a topic the next day, then after three days, a week and a month, each time by recalling first and checking second rather than rereading. Keep a list of the questions you got wrong and redo them until you can solve them without help, and mix several topics in one session so you also practise choosing the right idea. In OrujovAI's Live Tutor, questions you miss in the Abituriyent Path go into a personal mistake bank and come back as spaced re-checks.