Which of the following is true in blood transfusion?
Blood group O lacks A and B antigens, making it a universal donor compatible with A, B, AB, and O recipients, as it does not trigger immune reactions.
A yellow maize is planted and all the fruits obtained are yellow seeds. When they are cross-bred, yellow seeds are obtained in a ratio 3:1. The yellow seed is said to be
The 3:1 phenotypic ratio in F2 generation indicates monohybrid inheritance where yellow (YY or Yy) is dominant over white (yy), with 75% yellow and 25% white offspring.
When a colour-blind man marries a carrier woman. What is the probability of their offspring being colour blind?
Color blindness is X-linked recessive. Man (X^c Y) and carrier woman (X X^c) produce sons: 50% X^c Y (color blind), daughters: 50% X^c X^c (carrier), so 50% overall color blind (all sons).
The correct base pairing for DNA is
In DNA, adenine (A) pairs with thymine (T) via two hydrogen bonds, and guanine (G) pairs with cytosine (C) via three, ensuring stable double helix structure.
Which of the following best describes a relationship where one organism benefits and the other is harmed?
Parasitism involves a parasite benefiting (e.g., nutrients from host) while harming the host (e.g., tapeworm in human intestine causing malnutrition).
In an ecosystem, competition between two species for the same food resource is an example of
Interspecific competition occurs between different species (e.g., lions and hyenas competing for zebra), potentially leading to competitive exclusion or niche differentiation.
The short thick beak in birds is an adaptation for
Short, thick beaks, as in finches, provide mechanical advantage for cracking hard seeds, an adaptation to diet in Darwin's Galapagos observations.
The basking of Agama lizards in the sun is to
Agama lizards, ectotherms, bask to absorb solar heat, raising body temperature for metabolic activity and thermoregulation.
The significance of a very large number of termites involved in nuptial swarming is to
Mass swarming produces many alates, ensuring colony survival despite high predation rates during dispersal and mating.
The use and disuse of body parts and the inheritance of acquired traits were used to explain evolution by
Lamarck proposed that acquired traits (e.g., giraffe's neck from stretching) are inherited, differing from Darwin's natural selection.
Which of the following structures in a plant is primarily responsible for gaseous exchange?
Stomata on leaves open to allow CO2 intake for photosynthesis and O2 release, regulated by guard cells.
What is the primary source of energy for Earth's climate system?
Solar radiation drives atmospheric circulation, evaporation, and global temperature gradients.
Which of the following is a characteristic of a mammal?
Mammary glands produce milk for offspring nourishment, a defining mammalian trait.
What is the term for the process by which plants lose water through their leaves?
Transpiration creates a pull for water and minerals from roots via xylem, cooling the plant.
Which of the following organisms is a decomposer in an ecosystem?
Fungi break down dead matter, releasing nutrients for recycling in the food web.
Which of the following is the primary role of hemoglobin in the human body?
Hemoglobin binds O2 in lungs and releases it in tissues, enabling cellular respiration.
What is the primary function of the root hairs in plants?
Root hairs increase surface area for osmosis and diffusion of water/minerals from soil.
Which of the following is a characteristic of a tropical rainforest?
High rainfall and warmth support diverse species, with layered canopies fostering niches.
What is the term for the process by which a sperm and egg combine to form a zygote?
Fertilization fuses gametes, forming a diploid zygote that develops into an embryo.
Which of the following is a characteristic of amphibians?
Amphibians have moist skin for cutaneous respiration and undergo metamorphosis (aquatic larvae, terrestrial adults).
What is the primary role of the pancreas in the human body?
Pancreas secretes insulin (lowers blood sugar) and glucagon (raises it), maintaining homeostasis.
Which of the following structures in a flower is responsible for producing pollen?
Anther contains pollen sacs where microspores develop into pollen grains for fertilization.
What is the term for the process by which organisms produce offspring?
Reproduction ensures species continuity through sexual (gametes) or asexual (cloning) methods.
Which of the following is a characteristic of fungi?
Fungi are saprophytes, absorbing nutrients from decaying matter via hyphae.
What is the primary function of the lungs in the human body?
Lungs facilitate diffusion of O2 into blood and CO2 out via alveoli and capillaries.
Which hormone is responsible for milk production in mammals after childbirth?
Prolactin stimulates mammary gland development and milk synthesis post-partum.
What is the primary method by which viruses reproduce?
Viruses are obligate intracellular parasites, hijacking host machinery for replication.
Which of the following traits is unique to mammals for temperature regulation?
Hair/fur insulates, trapping air to maintain endothermic body temperature.
What structure in the male reproductive system stores sperm before ejaculation?
Epididymis coils store and mature sperm, aiding motility before transport.
What is the primary role of the green pigment in plant cells?
Chlorophyll absorbs red/blue light, driving photosynthesis in chloroplasts.
What gas do insects primarily take in through their respiratory structures?
Oxygen diffuses through spiracles into tracheae for direct delivery to tissues.
Which of the following adaptations is typical of plants in a wetland ecosystem?
Aerenchyma provides air channels for O2 transport in waterlogged roots.
What is the primary protective function of the largest organ in the human body?
Skin's keratinized epidermis and acidic sweat form a barrier against microbes.
Which of the following traits in humans shows continuous variation?
Height is polygenic, influenced by multiple genes and environment, showing a range.
What is the primary role of antibodies in the immune system?
Antibodies bind antigens on pathogens, neutralizing or opsonizing for phagocytosis.
What type of beak is adapted for birds that feed on nectar?
Long, slender beaks reach deep into flowers, as in hummingbirds for nectar.
What is the term for the process where only the fittest organisms survive and reproduce?
Natural selection favors advantageous traits, increasing their frequency over generations.
What type of reproduction is typical in Rhizopus?
Rhizopus produces sporangiospores for asexual reproduction, dispersing via wind.
What gas is primarily used by plants during photosynthesis?
CO2 is fixed in the Calvin cycle, combining with RuBP to form sugars.
What structure in the human respiratory system protects the airway during swallowing?
The epiglottis folds over the larynx, directing food to the esophagus.
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