Biology Revision List 2

Gametes

Gametes- haploid cells capable of fusion 

Fertilisation

Fertilisation- joining of 2 gametes to produce a diploid zygote 

Alleles

Alleles- different forms of the same gene, e.g. tall, small 

Genotype

Genotype- genetic make-up  of the individual, e.g. TT, tt 

Phenotype

Phenotype- physical appearance of the individual, e.g. tall, small 

Phenotype = genotype + environment 

Recessive

Dominant- prevents the recessive gene from working 

Recessive- prevented from working by the dominant gene 

Homozygous

Homozygous- 2 alleles are the same, e.g. TT, tt 

Heterozygous

Heterozygous- 2 alleles are different, e.g. Tt 

Incomplete dominance

Incomplete dominance- neither allele is dominant or recessive 

Haploid

Haploid- contains one set of chromosomes 

Diploid

Diploid- contains 2 sets of chromosomes 

Linkage

Linkage- genes located on the same chromosome 

Sex linkage

Sex linkage- a characteristic controlled by the X chromosome 

Transformation

the DNA is inserted into the host cell, and it divides with this gene

Two blood groups are

ABO, rhesus

Mendels Principle of Segregation

Characteristics are controlled by pairs of factors; but only one factor can be carried in a gamete

Inherited Variations

Inherited variations occur in populations due to genetic or inherited characteristics

Mutation

A sudden change in the amount or structure of DNA

Second Infection

Memory cells produce more antibodies to fight the infection. We don’t get the same virus twice as we have the antibodies in our system to fight it. Takes 5 days to produce antibodies.

Passive immunity

Passive immunity is where an organism receives antivbodies formed by another organism.

Speciation

Speciation is the formation of a new species due to the accumulation of slight changes in the genetic make up of organisms in a population

General defence system

Non- specific- defense tjat acts on all pathogens

Specific defense system

Specific defence system, that has specific immune responses towards specific pathogens.

Antibody

An antibody is a protein produced by a white blood cell in response to an antigen. Help neutralize pathogens by binding to them, marking them for destruction by other immune cells.

Antigen specifitiy

ONE ANTIGEN STIMULATES THE PRODUCTION OF ONE ANTIBODY ONLY.

ONE ANTIBODY RECOGNISES AND BINDS TO A SPECIFIC ANTIGEN

First infection

First infection: Antibodies are made to fight the infection. Memory cells remain in the body for a long time. Takes 14 days to produce antibodies

General Defense system

ATTACKS ALL PATHOGENS

Non specific defense system against pathogens. First defence consists of physical and chemical barrier, stopping pathogens from entering the body.

Second line of defence, consists of immune response attacking all pathogens.

3 ways the specific defense system FIGHTS PATHOGENS

Antibodies

Memory cells: Memory cells fight pathogens by responding faster and more effectively if the same pathogen enters the body again.

Macrophages

Example of diffusion

CO2 diffusing into a leaf, O2 diffusing out of a leaf

How does a plant control transpiration?

Presence or absence of a cuticle

Closing and opening of stomata

Guard cells

CO2 Sources

CO2 - Produced in the leaf during respiration, diffuses form the air in through the stomata. Plants need CO2 for photosynthesis.

Roots cause

Roots: absorbs water + minerals, transports water + minerals from the soil to the shoots

Monocot flower parts

Flower parts in multiple of 3

Light intensity impact on transpiration

Light cells cause: Guard cells, surrounding stomata, open stomata during the day, close at night.

Transpiration

Transpiration: the process by which the plant loses water vapour through small opening in their leaves called stomata.

High wind

High wind causes high water vapor gradient, and for more transpiration, leading to the stomata to close. Low wind causes low water gradient, lowering transpiration, leading to stomata to open.

Where does CO2 come from

Produced in the leaf during respiration.

Diffuses from the air, in through the stomata.

Plants need carbon dioxide for photosynthesis - rate of photosynthesis = rate of co2 absorbed + rate of co2 produced

How does presence or absence of a cuticle control transpiration?

Presence or absence of a cuticle – water cannot pass through the cuticle. The presence of a cuticle helps reduce excessive loss of water

Flower purpose

Sexual reproduction, the function of a flower is to facilitate plant reproduction by producing seeds through the process of pollination and fertilization.

Tracheids

Tracheids are Long, tapered cells

Stage 3: Products produced

Some of the trapped light energy is used to split water into oxygen gas (O2) protons (H+) and electrons (e-)

Summarised as 2H2O ---> 4H+ and 4e- and O2

Tissue function

Dermal Tissue: function if for protection

Ground Tissue: function is for photosynthesis and storage

Vascular Tissue: function if for transport

Root pressure

Root pressure: The roots actively take up minerals and nutrients from the soil, which increases the solute concentration inside the root cells

Since water moves towards areas of higher solute concentration, water from the soil enters the roots to balance the concentration of solutes between the soil and the root cells. This influx of water into the roots creates a build-up of water pressure within the root.

This pressure, known as "root pressure," forces the water and dissolved nutrients to travel upward through the plant's vascular system (specifically the xylem), moving against gravity.

Stage 5 of Photosynthesis:

Stage 5 of Photosynthesis: Glucose if formed The high energy electrons along with protons from the proton pool are combined with carbon dioxide to form glucose (C6H12O6 )

Root hair adaptions

Root hair adaptaitons: Thin cell wall

A large surface area due to root hair cells

Fungal hyphae increase sruface acrea

Leaf structure

Upper epidermis made of dermal tissue and wax cuticles, is transparent, to let sun shine on the palisade mesophyll, which is packed with chloroplasts and chlorophyll that need to trap the sun’s energy. Spongy mesophyll, has lots of air space, to allow gas to easily be transported within the cell. Lower epidermis has holes, in the form as stomata, with guard cells that open and close them.    Humidity increases the concentration of water vapour surrounding the stomata, decreasing the water vapour gradient between the inside of the leaf and the outside of the leaf. This decreases the amount of transpiration,  

Water movement in roots

Water moves by diffusion from the root hairs into the 
ground tissue and eventually reaches the xylem.

Genome

Genome is all the genes in a cell

Blood grouping

TWO TYPES OF BLOOD GROUPING IS ABO AND RHESUS

ABO blood grouping

The presence or lack of of A and/or B antigens on red blood cells determines the blood type you are.

A, AB, B, O

If you receive an antigen you are not used to, then the immune system will aim to eliminate it

Rhesus blood group

The presence of rhesus red blood cells determines the blood type you are.

Rh+ Rh-

If you receive an antigen you are not used to, then the immune system will aim to eliminate it

Transgenic organisms

Transgenic organisms are organisms altered by genetic engineering.

DNA

It is hereditary material, meaning it carriers genetic information from older generations, and it passes on genetic material to future generations. It is hereditary material, meaning it carriers genetic information from older generations, and it passes on genetic material to future generations.

DNa is a molecule that contains the genetic instructions for life, in the forms of genes. It codes for the instructions for function, growth, structure and repprduction enceccesaayr for life,

Protein synthesis improvements

RNA binds to the exposed corresponding DNA bases. The DNA code is transcribed from the DNA to RNA, forming mRNA

The mRNA passes throigh the ribosomes translating it;s code to form amino acids. The protein folds and emerges from the ribosome,

Genetic engineering is bad:

Ethical Concerns & Social Inequality – Raises moral questions about altering human genetics and expensive treatments may only be available to the wealthy.

Loss of Biodiversity – can spread to ecosystems, outcompetes other plants, and starve pests.

Potential Health Risks – Long-term effects of genetically modified organisms (GMOs) are uncertain.

A codon

A triplet or codon is 3 consecutive bases to code each particular amino acid, e.g. CAA = valine

A sequence of many triplets forms a gene

Mendels seocnd law / law of association

States when gametes are formed either pair of factors is equally likely to combine with another pair of factors

A species

A species are a group of organisms capable of interbreeding and producing fertile offspring.

Ligation and Insertion

DNA ligase is used to inset the cut fragments of DNA into the target DNA, and the DNA is ligated, where the DNA rejoins the cut fragment of DNA to form recombinant DNA.

DNA profile refinements

A radioactive material is added which combines with the DNA fragments to produce a fluorescent image.

A photographic copy of the DNA bands is obtained.

Stage 4: The pattern of fragment distribution is then analysed

Genetic Screening uses

Used for screening cystic fibrosis, sickle cell anaemia and albinism to see if people are carriers.

Also used for foetal screening.

Isoaltion

Isoaltion- A target gene is isolated from a donor, such as a human. The cells are broken, and genetic probe is added, which reveals the position of the gene of interest.

DNA vs RNA differences

Sugar is deoxyribose in DNA, whereas it is ribose in sugar.

Has thymine is DNA, whereas it has uracil in RNA,

DNA is longer, whereas RNA is shorter

DNA is self-replicating, whereas RNA is not self-replicating

DNA is found only in the nucleus, whereas RNA is found in the nucleus.

Inherited ~Variation

Inherited variaitons = genes inheriteed form parents

Transcription

making mRNA using DNA as a template.