AQA biology paper 1 Exam
Questions and Answers 100%
PASS
Cell-Surface Membrane (Plasma Membrane)—ANSWER-Composed of a
phospholipid bilayer with embedded proteins, cholesterol, and glycoproteins,
which contribute to its fluidity and functionality.
Functions include controlling the movement of substances in and out of the
cell, facilitating cell signaling, and enabling cell recognition.
The fluid mosaic model describes the structure, emphasizing the dynamic
nature of the membrane components.
Membrane proteins can act as receptors, channels, or enzymes, playing
critical roles in cellular communication and transport.
Cholesterol molecules help to stabilize the membrane's structure,
particularly in varying temperatures.
Nucleus—ANSWER-Contains the cell's genetic material (DNA) organized into
chromosomes, which are structures that condense during cell division.
,DNA is associated with proteins called histones, which help package the
DNA into a compact form.
The nucleolus, found within the nucleus, is the site of ribosome assembly,
crucial for protein synthesis.
The nuclear envelope, a double membrane, contains nuclear pores that
regulate the passage of molecules in and out of the nucleus.
The nucleus controls cell activities through gene expression, DNA
replication, and RNA synthesis.
Mitochondria and Chloroplasts—ANSWER-Mitochondria are double-
membraned organelles with a highly folded inner membrane (cristae) that
increases surface area for ATP production.
They are the site of aerobic respiration, generating ATP through oxidative
phosphorylation, which is essential for energy metabolism.
Chloroplasts, found in plants and algae, are also double-membraned and
contain thylakoids stacked in grana, where photosynthesis occurs.
Chlorophyll within the thylakoids captures light energy, converting it into
chemical energy stored in glucose.
Both organelles have their own DNA and ribosomes, supporting the
endosymbiotic theory of their origin.
Golgi Apparatus and Lysosomes—ANSWER-The Golgi apparatus consists of
a stack of flattened membrane-bound sacs (cisternae) that modify, sort, and
package proteins and lipids for transport.
© 2026 Copyright. All Rights Reserved. This document is
protected by copyright law, Copyrighted By Katelyn Whitman
,Golgi vesicles transport these modified molecules to their final destinations,
either inside or outside the cell.
Lysosomes are specialized Golgi vesicles containing hydrolytic enzymes that
break down worn-out organelles and cellular debris.
They play a crucial role in cellular digestion and recycling of materials,
maintaining cellular health.
The pH within lysosomes is acidic, which is optimal for the activity of
hydrolytic enzymes.
Atomic Structure—ANSWER-Atoms consist of a nucleus containing
positively charged protons and neutral neutrons, with negatively charged
electrons orbiting around them.
The number of protons defines the element (e.g., hydrogen has one proton,
carbon has six).
Ions are formed when atoms gain or lose electrons, resulting in a positive or
negative charge, respectively.
Isotopes are variants of the same element with different numbers of
neutrons, affecting atomic mass but not chemical behavior.
Electrons are arranged in shells, with the first shell holding 2 electrons and
subsequent shells holding up to 8, driving chemical bonding.
Chemical Bonding—ANSWER-Atoms seek full outer electron shells, which
drives the formation of chemical bonds.
, Ionic bonds occur when one atom transfers an electron to another, creating
oppositely charged ions that attract each other (e.g., NaCl).
Ionic bonds are strong but can be broken in water, leading to dissociation of
ions.
Covalent bonds form when atoms share electrons to fill their outer shells, as
seen in molecules like water (H2O) and methane (CH4).
Double bonds occur when two pairs of electrons are shared, as in the
oxygen molecule (O2).
Cell Specialization—ANSWER-Cells become specialized through differential
gene expression, leading to the production of specific proteins and
functions.
The presence and proportion of organelles can indicate a cell's function; for
example, muscle cells have many mitochondria for energy.
The shape of a cell often reflects its function; for instance, neurons have
long extensions for signal transmission.
Specialization allows for division of labor among cells, enhancing efficiency
and complexity in multicellular organisms.
Examples of specialized cells include red blood cells (for oxygen transport)
and epithelial cells (for protection and absorption).
Tissue and Organ Organization—ANSWER-Similar cells aggregate into
tissues, which perform a common function, such as muscle or nervous
tissue.
© 2026 Copyright. All Rights Reserved. This document is
protected by copyright law, Copyrighted By Katelyn Whitman
Questions and Answers 100%
PASS
Cell-Surface Membrane (Plasma Membrane)—ANSWER-Composed of a
phospholipid bilayer with embedded proteins, cholesterol, and glycoproteins,
which contribute to its fluidity and functionality.
Functions include controlling the movement of substances in and out of the
cell, facilitating cell signaling, and enabling cell recognition.
The fluid mosaic model describes the structure, emphasizing the dynamic
nature of the membrane components.
Membrane proteins can act as receptors, channels, or enzymes, playing
critical roles in cellular communication and transport.
Cholesterol molecules help to stabilize the membrane's structure,
particularly in varying temperatures.
Nucleus—ANSWER-Contains the cell's genetic material (DNA) organized into
chromosomes, which are structures that condense during cell division.
,DNA is associated with proteins called histones, which help package the
DNA into a compact form.
The nucleolus, found within the nucleus, is the site of ribosome assembly,
crucial for protein synthesis.
The nuclear envelope, a double membrane, contains nuclear pores that
regulate the passage of molecules in and out of the nucleus.
The nucleus controls cell activities through gene expression, DNA
replication, and RNA synthesis.
Mitochondria and Chloroplasts—ANSWER-Mitochondria are double-
membraned organelles with a highly folded inner membrane (cristae) that
increases surface area for ATP production.
They are the site of aerobic respiration, generating ATP through oxidative
phosphorylation, which is essential for energy metabolism.
Chloroplasts, found in plants and algae, are also double-membraned and
contain thylakoids stacked in grana, where photosynthesis occurs.
Chlorophyll within the thylakoids captures light energy, converting it into
chemical energy stored in glucose.
Both organelles have their own DNA and ribosomes, supporting the
endosymbiotic theory of their origin.
Golgi Apparatus and Lysosomes—ANSWER-The Golgi apparatus consists of
a stack of flattened membrane-bound sacs (cisternae) that modify, sort, and
package proteins and lipids for transport.
© 2026 Copyright. All Rights Reserved. This document is
protected by copyright law, Copyrighted By Katelyn Whitman
,Golgi vesicles transport these modified molecules to their final destinations,
either inside or outside the cell.
Lysosomes are specialized Golgi vesicles containing hydrolytic enzymes that
break down worn-out organelles and cellular debris.
They play a crucial role in cellular digestion and recycling of materials,
maintaining cellular health.
The pH within lysosomes is acidic, which is optimal for the activity of
hydrolytic enzymes.
Atomic Structure—ANSWER-Atoms consist of a nucleus containing
positively charged protons and neutral neutrons, with negatively charged
electrons orbiting around them.
The number of protons defines the element (e.g., hydrogen has one proton,
carbon has six).
Ions are formed when atoms gain or lose electrons, resulting in a positive or
negative charge, respectively.
Isotopes are variants of the same element with different numbers of
neutrons, affecting atomic mass but not chemical behavior.
Electrons are arranged in shells, with the first shell holding 2 electrons and
subsequent shells holding up to 8, driving chemical bonding.
Chemical Bonding—ANSWER-Atoms seek full outer electron shells, which
drives the formation of chemical bonds.
, Ionic bonds occur when one atom transfers an electron to another, creating
oppositely charged ions that attract each other (e.g., NaCl).
Ionic bonds are strong but can be broken in water, leading to dissociation of
ions.
Covalent bonds form when atoms share electrons to fill their outer shells, as
seen in molecules like water (H2O) and methane (CH4).
Double bonds occur when two pairs of electrons are shared, as in the
oxygen molecule (O2).
Cell Specialization—ANSWER-Cells become specialized through differential
gene expression, leading to the production of specific proteins and
functions.
The presence and proportion of organelles can indicate a cell's function; for
example, muscle cells have many mitochondria for energy.
The shape of a cell often reflects its function; for instance, neurons have
long extensions for signal transmission.
Specialization allows for division of labor among cells, enhancing efficiency
and complexity in multicellular organisms.
Examples of specialized cells include red blood cells (for oxygen transport)
and epithelial cells (for protection and absorption).
Tissue and Organ Organization—ANSWER-Similar cells aggregate into
tissues, which perform a common function, such as muscle or nervous
tissue.
© 2026 Copyright. All Rights Reserved. This document is
protected by copyright law, Copyrighted By Katelyn Whitman
