Comprehensive Biology O-Level & IGCSE Review

100 fill-in-the-blank flashcards spanning cells, physiology, plant & human biology, genetics, ecology and biotechnology to comprehensively review the Mojza O-Level & IGCSE Biology notes.

The partially permeable layer that encloses the cell is called the __.

cell surface (plasma) membrane

__ is the jelly-like substance where most chemical reactions of the cell take place.

Cytoplasm

The organelle that controls cell activities and division is the __.

nucleus

Energy release by aerobic respiration occurs in the __.

mitochondria

Proteins are synthesised on membraneless particles called __.

ribosomes

The fully permeable, rigid outer layer of a plant cell is the __.

cell wall

Large permanent plant organelle that provides turgidity is the __.

vacuole

Photosynthesis occurs inside green organelles known as __.

chloroplasts

The DNA of most bacteria is arranged as a single coiled __ chromosome.

circular

Bi-concave shape and absence of nucleus are adaptations of __ cells.

red blood

Long narrow extensions that increase surface area for water uptake are found on __ cells.

root hair

A group of similar cells performing a shared function is called a __.

tissue

Magnification is calculated by __ ÷ actual size.

image size

Species that can interbreed to produce fertile offspring are identified using a __ key.

dichotomous

Chitinous exoskeleton, jointed limbs and segmented bodies are characteristics of the phylum __.

Arthropoda

Arachnids possess _ pairs of legs.

four (4)

Fish use __ for gas exchange in water.

gills

Birds are warm-blooded vertebrates with bodies covered in __.

feathers

Ferns reproduce asexually by producing __ on the underside of fronds.

spores

Viruses consist of nucleic acid enclosed in a protein coat called a __.

capsid

The net movement of molecules from high to low concentration is __.

diffusion

Osmosis is the movement of water down its __ gradient through a partially permeable membrane.

water-potential

Active transport moves substances against the concentration gradient using energy from __.

respiration (ATP)

The iodine test turns blue-black in the presence of __.

starch

Biuret solution gives a lilac colour if __ are present.

proteins

Lipids in the ethanol emulsion test produce a __ white layer.

milky

Biological catalysts made of protein are called __.

enzymes

The specific region on an enzyme where substrate binds is the __ site.

active

Above optimum temperature enzymes lose shape in a process called __.

denaturation

Photosynthesis converts light energy to chemical energy following the equation 6CO₂ + 6H₂O → __ + 6O₂.

C₆H₁₂O₆ (glucose)

Swollen, hard plant cells full of water are described as __.

turgid

The transport tissue that conducts water and mineral ions upward is the __.

xylem

Transport of sucrose from source to sink occurs in the __.

phloem

Water loss as vapour from leaf stomata is called __.

transpiration

Wilting occurs when transpiration rate is __ than water uptake.

greater (higher)

Human carbohydrate digestion begins in the mouth by the enzyme __.

salivary amylase

The muscular wave that moves food along the gut is __.

peristalsis

Bile emulsifies fats and is produced by the __.

liver

Finger-like projections that increase intestinal surface area are __.

villi

In alveoli, oxygen percentage falls from 21 % inhaled air to about _ % in exhaled air.

16

The sheet of muscle that separates thorax from abdomen is the __.

diaphragm

Aerobic respiration releases more energy than anaerobic because it uses __.

oxygen

During vigorous exercise, insufficient oxygen leads to buildup of __ acid.

lactic

Red blood cells contain the pigment __ for oxygen transport.

haemoglobin

The type of white blood cell that engulfs pathogens is a __.

phagocyte

Blood clotting involves conversion of fibrinogen to insoluble __.

fibrin

The right side of the heart pumps blood to the lungs via the __ artery.

pulmonary

Arteries generally carry blood away from the heart at __ pressure.

high

Excessive fat deposition narrowing coronary arteries can lead to __.

atherosclerosis (coronary heart disease)

HIV is transmitted through body fluids and destroys immune cells called __.

T-lymphocytes

Cholera bacteria produce an enterotoxin causing severe __.

diarrhoea

The removal of waste products of metabolism is called __.

excretion

Urea is formed in the liver by the process of __ of amino acids.

deamination

Filtration of blood occurs in kidney structures called __.

glomeruli

The basic functional unit of the nervous system is the __.

neuron

Rapid automatic responses to stimuli are known as __ actions.

reflex

At a synapse, nerve impulses are transmitted chemically by __.

neurotransmitters

In bright light, circular muscles of the iris __ causing pupil constriction.

contract

Adrenaline prepares the body for ‘fight or flight’ and is secreted by __ glands.

adrenal

Maintaining a constant internal environment is called __.

homeostasis

High blood glucose triggers pancreatic secretion of __.

insulin

Growth responses of plants to directional stimuli are termed __.

tropisms

Auxin accumulates on the shaded side of a shoot causing it to bend __ light.

towards

Cell division that produces genetically identical diploid cells is __.

mitosis

Reduction division producing haploid gametes is __.

meiosis

Asexual reproduction in bacteria by splitting in two is called binary __.

fission

Transfer of pollen from anther to stigma is __.

pollination

Fusion of male and female gametes forms a diploid __.

zygote

The protective fluid-filled membrane around a developing foetus is the __ sac.

amniotic

Inheritance of an allele that is only expressed when homozygous refers to a __ allele.

recessive

Different versions of a gene are called __.

alleles

Most energy pyramids show only about _ % energy transfer between trophic levels.

10

Conversion of atmospheric nitrogen to ammonia by bacteria is called nitrogen __.

fixation

Bacteria converting nitrates back to nitrogen gas carry out __.

denitrification

Excessive greenhouse gases trap heat and cause global __.

warming

Clearing forests for agriculture or building is termed __.

deforestation

Accumulation of toxins along a food chain is known as bio__.

bioaccumulation

Sustainable use of resources means they are produced __ as quickly as removed.

just / equally (at the same rate)

Industrial production of penicillin uses large steel vessels called __.

fermenters

Adding lactase to milk produces __-free milk for intolerant individuals.

lactose

DNA containing genes from two species is called __ DNA.

recombinant

Golden Rice is genetically modified to produce extra __.

vitamin A (beta-carotene)

Arthropods with two pairs of antennae and mostly aquatic lifestyle are __.

crustaceans

Haemoglobin binds oxygen reversibly to form __.

oxyhaemoglobin

The opening and closing of stomata are controlled by __ cells.

guard

Capillary action in xylem relies on adhesion and __ between water molecules.

cohesion

During inspiration, external intercostal muscles __.

contract

The enzyme pepsin in the stomach works best at about pH __.

2 (acidic)

Protein digestion in the small intestine produces building blocks called __.

amino acids

Energy value per gram is highest for the nutrient group __.

lipids (fats)

Severe vitamin C deficiency leads to __.

scurvy

In diabetes type 1 the pancreas fails to produce sufficient __.

insulin

The graph of photosynthesis rate plateauing at high light shows a new __ factor.

limiting

Large surface area, moist lining and thin walls make __ efficient gas exchange surfaces.

alveoli

The mesh of fibrin and trapped cells that stops bleeding is a blood __.

clot

The collar of unspecialised cells that can differentiate are known as __ cells.

stem

The tubule region where most selective reabsorption of glucose occurs is the __ convoluted tubule.

proximal

A thickened lignified xylem wall prevents the vessel from __.

collapsing

Female hormone that repairs and thickens the uterine lining is __.

oestrogen

The surge of __ hormone triggers ovulation on day 14.

luteinising (LH)