AQA A-level Biology Section 2

AQA A-level Biology Section 2 flashcards - Fill in the blank style

A __ has a membrane-bound nucleus and chromosomes and has other membrane-bound organelles, such as mitochondria and endoplasmic reticulum.

eukaryotic cell

Animal cells, plant cells, fungi and __ are examples of eukaryotic cells.

algae

__ is an example of a prokaryotic cell.

Bacteria

The cell-surface membrane is made mainly of __ and proteins.

phospholipids

One function of the cell-surface membrane is to regulate the __ of substances into and out of the cell.

movement

The __ contains genetic material of the cell in the form of DNA and therefore controls the cell’s activities.

nucleus

__ allow movement of substances e.g. mRNA between the nucleus and the cytoplasm.

Pores

The __ manufactures ribosomes.

nucleolus

The inner membrane of the mitochondria is folded to form _.

cristae

The __ contains enzymes involved in respiration in the mitochondria.

matrix

Mitochondrial __ allows the synthesis of proteins & enzymes required for respiration.

DNA

The site of aerobic respiration and therefore, where __ is produced is the mitochondria.

ATP

__ membranes are the site of photosynthesis reaction in chloroplasts.

Thylakoid

The photosynthesis reaction takes place in the __ of the chloroplasts.

stroma

The Golgi apparatus __ proteins (e.g. by adding a carbohydrate chain to produce a glycoprotein).

modifies

The Golgi apparatus __ proteins into vesicles.

packages

__ hydrolyse pathogens & break down old organelles.

Lysozymes

The __ is the site of protein synthesis.

ribosome

The rough endoplasmic reticulum (RER) __ proteins into transport vesicles.

packages

The __ endoplasmic reticulum (SER) is involved in lipid & carbohydrate synthesis, storage and transport.

smooth

The cell wall is a rigid structure that surrounds plants, prokaryotic cells and __.

fungi

The main component of plant cell wall is __.

cellulose

The main component of prokaryotic cell wall is __.

murein

The main component of fungal cell wall is __.

chitin

The cell __ helps to maintain pressure inside plant cells → keeps the cell rigid → stops plants wilting.

vacuole

__ produce ATP for protein synthesis.

Mitochondria

The __ contains DNA and is the site of transcription (produces mRNA).

nucleus

Fungal cells walls are made of __, not cellulose.

chitin

A __ is a group of cells working together to perform a particular function.

tissue

The walls of the small intestine are covered in __ - increase the surface area for absorption.

villi

__ have large amounts of lysosomes, which contain enzymes to destroy ingested microbes.

Neutrophils

A cell that does not have a nucleus OR membrane-bound organelles is __.

prokaryotic

A __ is a small, circular piece of DNA found in bacterial cells, that is separate from the main circular DNA molecule.

plasmid

The __ in prokaryotic cells protects bacteria from attack by cells of the immune system.

capsule

The method by which prokaryotic cells replicate is called __.

Binary fission

Viruses cannot replicate __ and have no metabolism/don’t respire.

independently

With virus replication, __ proteins attach to receptors on host cell.

attachment

__ is how many times bigger the image is compared to the real object.

Magnification

__ is the minimum distance apart that two objects can be in order for them to be distinguished as two separate objects.

Resolution

__ microscopes use electrons & focuses using magnets.

TEMs

__ microscopes produce 2D images and can only be used on thin specimens.

TEMs

__ microscopes use electrons and Electrons are scattered by the surface based on the contours of the surface of the specimen.

SEMs

__ microscopes show a surface view and can be used on thick specimens.

SEMs

__ have a higher resolution because they use electrons which have a shorter wavelength.

Electron microscopes

__ are absorbed by molecules in the air, so if air was present, this would prevent the electrons reaching the specimen.

Electrons

A structural detail that results from processing of the specimens and is not a part of the natural specimen is called __.

artefact

Cells are broken up and their organelles are separated out in __.

cell fractionation

Cells are broken up by a __ and organelles are released from the cell.

homogeniser

Organelles in the filtered homogenate are separated using a __.

centrifuge

The solution used for cell fractionation should be ice-cold, __ and isotonic.

buffered

The phase that precedes mitosis in the cell cycle is called __.

Interphase

Mitosis produces two genetically __ cells.

identical

Name the stages of mitosis in order: prophase, metaphase, __, telophase

anaphase

Each chromosome is made up of 2 __ which are joined by the centromere.

chromatids

During __, chromosomes condense and shorten.

prophase

During __, chromosomes line up at the equator of the cell and attach to the spindle fibres via their centromere.

metaphase

During __, centromeres divide, separating each pair of sister chromatids.

anaphase

During __, chromatids uncoil.

telophase

__ is when the cytoplasm divides, separating the cell into two daughter cells which are both genetically identical to the original cell.

Cytokinesis

The __ tells you how quickly a tissue is growing.

mitotic index

A mass of cells that forms due to uncontrolled cell division is called __.

tumour

__ molecules form a bilayer, with the hydrophilic heads facing towards water on both sides of the membrane.

Phospholipid

Solvents, such as __, dissolve the lipids in the cell membrane, so the membrane becomes more permeable.

alcohol

__ transport moves substances against a concentration gradient, involves protein carriers and requires ATP.

Active

The diffusion of molecules directly through a cell membrane is know as __ diffusion.

simple

__ are moved against a concentration gradient in active transport, whereas facilitated diffusion moves substances down a concentration gradient.

Substances

In __, protein channels form pores/channels across the membrane, allowing water-soluble ions to diffuse down their concentration gradient.

facilitated diffusion

The rate of osmosis is affected by water potential gradient, thickness of exchange surface and __.

surface area of exchange surface

The water potential of pure water under standard conditions of pressure and temperature is __.

zero

If two solutions are isotonic, this means they have the same __.

water potential

For a drug to enter a cell rapidly, it should be small and __.

lipid-soluble

A __ is a type of carrier protein that can bind two molecules at a time

co-transporter

A __ is a disease causing microorganism e.g. bacteria, virus, fungi

pathogen

__ is the process when pathogen releases chemicals which attract the phagocyte.

phagocytosis

Following the humoral response to a pathogen, activated B cells divide by mitosis to produce __ cells and memory B cells

plasma

__ region forms antigen-binding sites on a antibody.

Variable

A __ immune response is stronger and faster than a primary immune response.

secondary

A __ is when you become immune after catching a disease.

natural active immunity

A __ is when you become immune after being given a vaccination that contains dead/inactive pathogen.

artificial active immunity

A __ is when a baby becomes immune due to the antibodies it receives from its mother via the placenta/breast milk.

natural passive immunity

A __ is when you become immune after being injected with antibodies made by another individual (often an animal) e.g. antibodies to tetanus toxin / snake venom.

artificial passive immunity

__ is when pathogens change their surface antigens due to changes in the genes of the pathogen.

Antigen variability

Vaccines lead to a person developing immunity to a pathogen when the macrophage presents __ on its surface.

antigen

The __ immune response has a slower response due to time taken for clonal selection, clonal expansion & production of antibodies

primary

The __ immune response memory cells divide quickly to form plasma cells which secrete antibodies.

secondary

With vaccines, unvaccinated individuals less likely to catch the disease as there are fewer people to catch it from . This is due to __.

herd immunity

__ transcriptase synthesises a DNA copy of the HIV RNA.

Reverse

AIDS develops because HIV destroys __ cells.

helper T

Monoclonal antibodies are antibodies with the same __ structure produced from cloned B cells.

tertiary

The ELISA test can be used to test for __.

HIV