Which organ allows humans to breathe?
Answer : The lungs
The lungs are the organs responsible for breathing in humans.
Questions and answers: Biology
Revise Biology: here is a selection of questions of every level, with the answer and an explanation. To test yourself without seeing the answers, play the quizzes.
Play the Biology quizzesVery easy
How many legs does a spider have?
Answer : Eight
Spiders, like all arachnids, have eight legs.
Which animal is considered the largest mammal in the world?
Answer : The blue whale
The blue whale is the largest mammal and the largest known animal.
Which organ in the human body is responsible for thinking?
Answer : The brain
The brain is the organ that controls thought and body functions.
Which group of animals includes frogs and toads?
Answer : Amphibians
Frogs and toads belong to the amphibian group.
Which part of a plant absorbs water and nutrients from the soil?
Answer : The roots
Roots absorb water and mineral nutrients from the soil.
Which insect produces honey?
Answer : The bee
The bee is the insect that produces honey from flower nectar.
How many chromosomes does a normal human cell have?
Answer : 46
A normal human cell has 46 chromosomes, arranged in 23 pairs.
Easy
Which molecule carries genetic information in cells?
Answer : DNA
DNA (deoxyribonucleic acid) carries genetic information in cells.
Which type of cell lacks a nucleus, unlike animal cells?
Answer : The bacterial cell
Bacterial (prokaryotic) cells lack a nucleus, unlike eukaryotic cells.
Which cell organelle is often called the 'powerhouse' of the cell?
Answer : The mitochondrion
The mitochondrion produces the cell's energy in the form of ATP, earning it this nickname.
Which blood type is considered the universal donor?
Answer : O negative
Blood type O negative is considered the universal donor because it's compatible with all other blood types.
Which process allows a cell to divide into two identical daughter cells?
Answer : Mitosis
Mitosis is the cell division process that produces two identical daughter cells.
Which gas do animals release when they breathe?
Answer : Carbon dioxide
Animals release carbon dioxide (CO2) when they breathe.
Which organ filters the blood to produce urine?
Answer : The kidneys
The kidneys filter the blood and produce urine to remove waste.
What do we call animals that eat only plants?
Answer : Herbivores
Herbivores are animals whose diet consists exclusively of plants.
Medium
What is the name of the process by which cells produce energy from glucose and oxygen?
Answer : Cellular respiration
Cellular respiration allows cells to produce energy (ATP) from glucose and oxygen.
Which structure protects and supports the body of most vertebrates?
Answer : The skeleton
The skeleton, made of bones, protects and supports the body of vertebrates.
Which type of reproduction involves the fusion of two gametes of different sexes?
Answer : Sexual reproduction
Sexual reproduction involves the fusion of a male gamete and a female gamete.
Which endocrine gland regulates metabolism by producing thyroid hormones?
Answer : The thyroid
The thyroid produces hormones that regulate the body's metabolism.
Which type of immune cell produces antibodies?
Answer : B lymphocytes
B lymphocytes, once activated, differentiate into plasma cells that produce antibodies.
Which British scientist invented the first vaccine, against smallpox, in the late 18th century?
Answer : Edward Jenner
Edward Jenner developed the first vaccine against smallpox in 1796.
Which biological process allows an embryo to develop from a fertilized egg?
Answer : Embryogenesis
Embryogenesis is the process of embryo development from a fertilized egg.
Which type of microscopic fungus, like baker's yeast, is used in bread-making?
Answer : Yeast
Yeast (Saccharomyces cerevisiae) is a single-celled fungus used to make bread rise.
Hard
Which cell division process produces reproductive cells (gametes) containing half the number of chromosomes?
Answer : Meiosis
Meiosis produces haploid gametes containing half the number of chromosomes of the original cell.
Which enzyme unwinds the DNA double helix during replication?
Answer : DNA helicase
DNA helicase unwinds the DNA double helix to allow replication.
Which British scientist co-discovered the double helix structure of DNA with James Watson in 1953?
Answer : Francis Crick
Francis Crick, with James Watson, co-discovered the double helix structure of DNA in 1953.
Which type of natural selection favors individuals with extreme traits rather than the average?
Answer : Disruptive selection
Disruptive selection favors extreme phenotypes in a population rather than intermediate values.
Which plant cell structure, absent in animal cells, contains chlorophyll?
Answer : The chloroplast
The chloroplast is the plant organelle containing chlorophyll, where photosynthesis occurs.
Which type of immunity is acquired after a first exposure to a pathogen, thanks to immune memory?
Answer : Adaptive immunity
Adaptive (or acquired) immunity relies on immune memory developed after a first exposure.
Which evolutionary process describes the emergence of new species from an ancestral population?
Answer : Speciation
Speciation is the process by which new species emerge from a common ancestral population.
Which pancreatic hormone lowers blood glucose levels?
Answer : Insulin
Insulin, produced by the pancreas, lowers blood glucose by promoting its uptake by cells.
Expert
Which molecular mechanism regulates gene expression without altering the DNA sequence?
Answer : Epigenetics
Epigenetics encompasses mechanisms of gene expression regulation that don't involve changes to the DNA sequence itself.
Which enzyme, discovered in bacteria, underlies the CRISPR-Cas9 genome editing system?
Answer : Cas9
The Cas9 protein, associated with the CRISPR system, allows targeting and cutting DNA at precise locations.
Which scientist proposed the endosymbiotic theory in 1967 explaining the origin of mitochondria and chloroplasts?
Answer : Lynn Margulis
Lynn Margulis formulated and popularized the endosymbiotic theory in 1967, explaining the origin of mitochondria and chloroplasts.
Which structure protects the ends of chromosomes and shortens with each cell division?
Answer : Telomeres
Telomeres protect the ends of chromosomes and shorten with each cell division, a factor linked to aging.
Which programmed cellular process leads to controlled cell death without causing inflammation?
Answer : Apoptosis
Apoptosis is a programmed, controlled cell death process without inflammation, unlike necrosis.
Which theory explains the coevolution of two species in constant competition to maintain their relative advantage?
Answer : The Red Queen hypothesis
The Red Queen hypothesis describes the continuous coevolution needed between competing species, such as predators and prey.
Which type of RNA serves as an intermediary to carry genetic information from the nucleus to the ribosomes?
Answer : Messenger RNA
Messenger RNA (mRNA) carries genetic information from the DNA in the nucleus to the ribosomes for protein synthesis.
Which British biologist formulated the concept of inclusive fitness to explain altruism among close relatives?
Answer : William D. Hamilton
William D. Hamilton formulated the theory of inclusive fitness (kin selection) to explain biological altruism.