Unit 2 Flashcards
Chromosome compliment
Each species of plant and animal has a specific number of chromosomes in nucleus of its cells.
Having the correct number of chromosomes in each cell ensure that the organism will have the characteristics of its species.
This is called the chromosome complement.
What is a haploid cell?
A Haploid cell has a single set of chromosomes.
e.g. sperm and egg cells
what is a diploid cell?
A cell containing two sets of chromosomes is a diploid Cell.
1 set from mother; 1 set from father
How many chromosomes are there in a normal body cell?
2 sets.
Where do the sets of chromosome come from?
Once it comes from the female parent, one set comes from the male parent.
Why do we need cells?
New cells are needed to allow multi-cellular organisms to grow.
New cells are needed to repair damaged tissue. New cells replace damaged cells to repair the tissue.
What is mitosis?
Mitosis is the process where diploid body cells divide into new cells.
The new cells are identical.
Mitosis importance
Mitosis maintains the diploid chromosome complement of new cells, providing the body with new cells that can be used in GROWTH and REPAIR.
Stages of mitosis
1) in the parent cell, the chromosomes replicate forming 2 identical CHROMATIDS joined in the centre by a centromere.
2) the nuclear membrane breaks down and the chromosomes shorten and thicken, becoming visible under a microscope.
3) the chromatids line up along the EQUATOR of the cell.
4) SPINDLE FIBRES attach to the pairs of chromatids.
5) spindle fibres pull the chromatids apart to the poles of the cell.
6) the cytoplasm divides and nuclear membranes form.
7) 2 diploid daughter cells are produced, containing the same genetic information as the parent cell.
How does cancer happen?
When cell division is no longer controlled, cancer cells form.
Why is mitosis required?
To provide new cells for growth and repair of damaged cells.
Mitosis is necessary for growth and repair.???
What does ‘maintaining the chromosome complement’ mean and why is it important?
Daughter cells are made with the same number of chromosomes as the original cell, ensuring the exactly the same genetic information is passed on from parent cell to daughter cells.
Function of stem cells in animals?
Where are they found?
Stem cells are unspecialised cells.
Stem cells in animals can divide (self-renew) and have the potential to become different types of cell. Stem cells are involved in GROWTH and REPAIR.
Found in embryos and tissues?
How is a red blood cell specialised to their function?
The function of a red blood cell is to transport oxygen around the body.
It is specially adapted to its function because it has a:
- biconcave shape to increase surface area and carry more oxygen.
- no nucleus to allow more space inside the cell to carry oxygen.
- contains heamoglobin which has high affinity to oxygen. The oxygen binds with the haemoglobin to form oxyheamoglobin.
How is a nerve cell specialised to carry out its function?
The function of a nerve cell is the transmission of nerve impulses.
The nerve cell has
- long fibres enable cells to reach all areas of the body.
- protective, insulating sheath allows electrical impulses to travel quickly along the cell.
How is a sperm cell adapted to carry out its function?
The function of the sperm cell is to fertilise the female egg cell.
A sperms cell has:
- a tail to swim towards the egg cell.
- the head of the cell contains many mitochondria which provide the cell with the energy it needs to swim.
How is a root hair cell structure adapted to their function?
The function of a root hair cell is to absorb water from the soil for uptake into the plant.
The root hair cell has:
- long extension into the soil which gives a large surface area.
How is a palisade mesophyll cells structure adapted to carry out its function?
The function of the palisade mesophyll cell is to carry out the process of photosynthesis.
The palisade mesophyll cell has:
- many chloroplasts to increase photosynthesis.
- it has a regular, columnar shape.
How is a guard cells structure adapted to carry out its function?
The function of the guard cell is it controls the opening and closing of stomata.
The guard cell has:
- sausage shaped cells.
- thick inner walls.
What are the levels of organisation in animals?
Cell - tissue - organ - system - organism
A cell is the basic unit of life.
A tissue is a group of cells specialised to perform a particular function. The structure of the cells in these tissues is related to their function.
An organ is a structure composed of many different tissues coordinated to perform one or more functions.
A group of related tissues and organs make up a system.
All cells, tissues, organs and organ systems coordinate together as an organism.
In which form is glucose stored in the liver?
Glycogen
Liver cells can store glucose molecules by connecting them together to make glycogen.
What are gametes?
Gametes are haploid sex cells.
Found in plants and animals and can be male or female.
In humans, gametes (egg and sperm cells) contain 23 chromosomes. (1 set)
Fertilisation
Fertilisation is when the nuclei of 2 haploid gametes fuse together to form a diploid zygote which divides to form an embryo.
(During fertilisation the nucleus of the male gamete fuses with the nucleus of the female gamete to produce a diploid zygote (fertilised egg)
Fertilisation is a RANDOM process.
What is a zygote?
A zygote is a fertilised egg cell.
2 parts of the Central Nervous System (CNS)
The CNS consists of the BRAIN and SPINAL CORD.
Structure of the brain - cerebrum
The cerebrum is the large folded area of the brain.
Function - responsible for conscious thoughts - memory, reasoning etc.
Structure of the brain - cerebellum
The cerebellum is found at the rear of the brain below the cerebellum.
Function - helps us balance and coordinate our movements.
Structure of the brain - medulla
The medulla is found at the top of the spinal cord and contains groups of neurons that transmit electrical impulses to the heart and lungs to:
Function - Controls our heart beating, breathing, gut movements etc.
The pathway of an electrical impulse along a reflex arc
- Receptors detect sensory stimulus
- Sensory neurons pass the information to the central nervous system (spinal cord and then brain)
- The CNS processes the information from our senses (along a relay nerve) which needs a response.
- Motor neurons enable a response to occur, which can be a rapid action from a muscle (which contracts) or a slower response from a gland (which releases a hormone)
Order of neurons: sensory –> inter –> motor
Reflex actions
Reflex actions are fast, automatic response to a specific stimulus. They usually have a protective role.
Reflex actions can happen without any input form the brain so they can’t be controlled.
Examples - blinking, pupils widen in the dark, response to pain (putting up hands when you fall) etc.
What is a synapse?
A synapse is a gap between neurons. The electrical impulse from one neuron is passed to the next using chemicals.
(The chemicals diffuse across the gap to carry the impulse from one neuron to another).
What is an endocrine glands?
Example?
Endocrine glands release hormones into the blood.
E.g. pancreas releases insulin and glucagon
The 3 main enforcing glands are:
- pancreas
- ovaries (female)
- testes (male)
Blood glucose regulation
- high blood sugar (blood glucose level high)
Normal blood glucose level then eat a meal:
- Blood glucose level high
- Pancreas detects change
- Pancreas releases the hormone insulin into blood
- insulin travels to liver in blood. Receptors in the insulin detect the insulin.
- liver changes glucose into glycogen (liver reacts to insulin by storing excess glucose as glycogen).
- blood glucose levels turn back to normal.
Blood glucose regulation
- low blood sugar (blood glucose level low)
Normal blood glucose level then no food eaten:
- blood glucose level low
- pancreas detects change
- pancreas releases the hormone glucagon into the blood
- glucagon travels to liver in blood. Receotors in the liver detect the glucagon.
- liver responds to glucagon by converting glycogen back into glucose
- blood glucose level returns to normal
Discrete variation
Discrete variations is caused by inheritance and is controlled by a single gene.
In discrete variation the characteristic falls into distinct groups.
- blood group, tongue rolling
Continuous variation
Continuous variation is often controlled by more than one gene (polygenic). It can have any value in a range between two extremes.
Most characteristics show continuous variation.
- height
Continuous variation is caused by polygenic inheritance (characteristics affected by more than one gene).
Definition of polygenic inheritance
A characteristic which is controlled by more than one gene, usually shows continous variation.
- e.g. skin colour
Definition of a gene
A gene is a section of DNA that codes for one protein which controls a particular characteristic.
Definition of allele
A form of a gene (different form/version of the same gene)
- tongue rolling gene has 2 forms: roller and non-roller.
Definition of phenotype
The physical expression of the genotype, normally visible and a description (e.g. tongue rolling, white fur)
A phenotype t is a physical description of a characteristic (genotype).
Definition of genotype
The alleles that an organism has for a particular characteristic, written as two letters (e.g. Tt or TT or tt)
Genotype is a description of the genes using letters to represent the alleles.
Definition of dominant allele
Always shows in the phenotype even if it is paired with another recessive allele (homozygous genotype).
Some alleles are dominant over other alleles meaning you only need to inheeir one copy of a dominant allele to express the characteristic. Dominant alleles are always represented by a capital letters.
Definition of recessive allele
Only shows in the phenotype if it is paired with another recessive allele (homozygous genotype). When in a heterozygous genotype, it is masked by the presence of a dominant allele.
Recessive alleles are often masked by dominant alleles. Therefore you have to inherit 2 copies to express this characteristic.
These alleles are represented by lower case letters of the dominant characteristic.
Definition of homozygous
A genotype where the two alleles are the same (TT, tt or YY, yy etc.)
If you inherit 2 of the same alleles, you are HOMOZYGOUS for a characteristic.
Definition of heterozygous
A genotype where the two alleles are different ( e.g. Tt or Yy)
If you inherit 2 different alleles (i.e. 1 recessive and 1 dominat) then you are HETEROZYGOUS for the particular characteristic.
Definition of P, F1 and F2
Parent
First generation
Second generation
Why are predicted ratios not always achieved in the F2 generation?
Fertilisation is a random process.
Main plant organs (3) and travel of water
Roots, stems, leaves
Water travels:
1) from soil into roots
2) up the stem and
3) into the leaves where it is used for photosynthesis
3 facts about the xylem vessels
- Carry water and minerals
- Made of dead cells
- Contain lignin to withstand the pressure changes as water moves through the plant
Why do roots have hairs?
To increase surface area for water absorption
How can the rate of transpiration be affected?
Higher wind speeds
Temperature
Leaf structure
Can speed up transpiration
3 facts about stomata
- Water is lost by evaporation through the stomata
- Opening and closing of stomata is controlled by guard cells. (Guard cells open stomata when they fill with water
- Stomata are mainly found in the lower leaf epidermis.
3 facts about phloem vessels
- Carry sugar from leaves to rest of plant.
- Cells are alive
- Contain sieve plate and companion cells
Components of blood in animals
Blood contains:
Plasma
Red blood cells
White blood cells
Blood transports nutrients, oxygen and carbon dioxide
Pathway of blood around the body
Lungs Pulmonary vein Left atrium Left ventricle Aorta Around body Vena cave Right atrium Right ventricle Pulmonary artery Lungs
What are the function of valves?
To prevent the backflow if blood.
Function of coronary arteries
To supply the heart muscle with oxygenated blood.
Facts about arteries
- Have thick muscular walls and a narrow central channel
2. Carries oxygenated blood at high pressure away from the heart and around the body.
Facts about veins
- Have thinner walls and a wide channel
- Carry deoxygenated blood under low pressure towards the heart
- Contains valves to prevent the backflow of blood
Facts about capillaries
- Form networks at organs and tissues.
2. Are thin walled and have a large surface area, allowing exchange of materials.
Which substances need to be delivered to and removed from cells?
Oxygen and nutrients from food must be delivered from the blood to the cells for respiration.
Waste materials (e.g. CO2 and urea) must be removed from the cells into the bloodstream.
3 adaptions of alveoli to make them efficient at exchanging gases with the blood
- Large surgace area provides by millions of alveoli
- Thin walls
- Good blood supply (surrounded by a dense capillary network)
4 adaptions of villi to make them efficient at absorbing digested food from the blood.
- Large surgace area provided by millions of villi
- Thin walls (makes diffusion easier)?
- Good blood supply to aid absorption of glucose and amino acids(network of capillaries)
- Lacteals absorb fatty acids and glycerol (the products of fat digestion)
Why must all cells have the correct chromosome complement?
To ensure the characteristics of the species are passed on.
Why is mitosis necessary?
Mitosis is necessary to provide new cells for GROWTH and REPAIR.
Why do cells have to have the same number of chromosomes?
Check this is right???
The cells have the same number of chromosomes to ensure they have identical genetic information.
????
What is a specialised cell?
A specialised cell is a cell that performs a particular function.
Specialised cells - cell structure
A cells structure is the arrangement or organisation of its parts.
A specialised cells structure enables the cell to carry out its functions.
Stem cells in animals
A stem cell in an animal is an unspecialised cell that can divide to self-renew or become specialised. They have the potential to become any cell type in the body.
Stem cells are used in GROWTH and REPAIR.
Where are stem cells found?
There are 2 types of stem cells:
- embryonic stem cells are taken from an EMBRYO at a very early stage.
- tissue stem cells are found in the body throughout life.
Role of an organ
A tissue is a group of cells.
An organ is a group of tissues.
An organ system is a group of organs.
An organ contains cells specialised for a particular function and groups or organs work together to form systems.
What is the central nervous system (CNS) composed of?
The central nervous system (CNS) is composed of all the neurons (nerve cells) that make up the brain and spinal cord.
The CNS consists of the brain and spinal cord.
Neurons (nerve cells)
There are 3 types of neurons in our CNS
- sensory
- inter
- motor neuron
They carry electrical impulses around the body.
All of our organs are connected by nerves to the brain and spinal cord.
Reflex arc
Rapid and protects the body.
The neurons (nerve cells) carry information in the form of an electrical impulse.
The order of neurons in a reflex arc is:
Sensory > inter > motor
What are hormones?
Hormones are chemical messengers (made of protein) that carry information in the blood to a target organ to bring out a response.
The target tissues contains special receptor proteins that will recognise the hormone.
The receptor proteins ensure only the target tissues are affected by the hormone.
What are hormones produced by?
Hormones are produces by endorcine glands and travel in the blood to the target tissue or organ.
Hormones and specific target organs
A target tissue has cells with complementary receptor proteins for specific hormones so only that tissue will be affected by these hormones.
Type 1 Diabetes
Sufferers don’t produce enough insulin (or sometimes none at all). Treated by injecting insulin daily.
Type 2 diabetes
Person can produce insulin but body cells are no longer responding to it. Treated by lifestyle changes.
Why must cells have the correct chromosome complement?
To ensure the characteristics of the species are passed on.
Explain the importance of the specialisation of cells
Cells become specialised to give arise to a variety of cells, each with a particular function.
Role of an organ
A tissue is a group of cells.
An organ is a group of tissues.
An organ system is a group of organs.
An organ contains cells specialised for a particular function and groups of organs work together to form systems.
Hierarchy of organ systems
Cells – tissues – organs – organ systems
Response to a stimuli
A response can be a rapid action from a muscle or a slower response from a gland by the release of a chemical (hormone).
Functions of neurons
The neurons are:
- sensory neuron - pass information from the receptors (senses) to the CNS.
- inter neuron - located in the CNS and processes information from the receptor (senses) that require a response.
- motor neuron - enable a response to occur at an effector (a muscle or gland).
Information is passed along a neuron using electrical impulses.
Sensory neurons contain RECEPTORS which detect stimuli and send an electrical impulse to the inter neuron and then a motor neuron to bring out a response.
What are all of our organs connected by?
Nerve cells
Functions of neurons - summary
Sensory neurons contain RECEPTORS which detect stimuli and send an electrical impulse to the inter neuron and then a motor neuron to bring out a response.
Reproduction
Reproduction is the biological process by which new organisms are produced.
Animal gametes features
(Label diagram)
The food store provides food for the growing embryo.
The tail enables the sperm to swim to the egg.
Gametes location in plants
The female gamete is the ovule and is produced in the ovary.
The male gamete is the pollen and is produced in the anther.
Ovaries
Site of egg (female gamete) and production.
Oviduct
Carries the egg from the ovary to the uterus. (Site of fertilisation).
Uterus
The embryo implants here and will develop into a foetus.
Vagina
Revieves penis and sperm during sexual intercourse.
Testes
The site of sperm (male gamete), production
Sperm duct
Carries sperm from the testes to the penis.
Urethra
Carries sperm (and urine) out of the body.
Penis
Inserted into vagina during sexual intercourse to deposit sperm.
Stages of fertilisation in a flowering plant
1) the nucleus of the pollen travels down the tube and joins with the nucleus of the ovule.
2) the nucleus of the pollen fuses with the nucleus of the ovule. This is fertilisation.
3) the pollen grows a pollen tube down to the ovary.
4) the pollen lands of the stigma.
What happens once the zygote is formed through fertilisation?
It divides and grows to become an embryo. The number of chromosomes is each does not change after fertilisation.
What is variation among species
Individuals of the same species that are different from each other.
Why are predicted phenotype ratios not always achieves?
Phenotype ratios are not always achieved because:
- fertilisation is a random process
- and the ratio size is also dependent on the sample size.
If the sample size is too small then the expected Phenotype ratio may not be shown.
Structure of the leaf
The leaf is a highly specialised organ whose function is to carry out photosynthesis.
To photosynthesis the cells in the leaf need WATER from the soil, CO2 from the air and LIGHT (energy) from the sun.
Structure of the leaf - upper epidermis
The upper epidermis is waxy for protection and to keep water in. It also allows light to pass through.
Structure of the leaf - waxy cuticle
Prevents water loss
Structure of the leaf - palisade mesophyll
Main cells involved in photosynthesis
Structure of the leaf - spongy mesophyll
Contains air spaces to allow gas exchange
Structure of the leaf - guard cells
Controls the opening and closing of stomata.
Structure of the leaf - stomata
Air spaces in the lower epidermis that allow oxygen and water to leave the cell and carbon dioxide to enter the leaf.
Transport of water through the plant - from the soil into the roots
Through its roots which contain specialised cells called root hair cells which increase the surface area in which the plant can absorb water and nutrients from the soil.
Water enters the root hair cells down a concentration gradient by osmosis.
Transport of water through the plant - through the stem to the leaves
Water is transported from the roots to the other parts of the plant through the dead xylem vessels. (made of dead cells).
These dead xylem vessels (lignified) contains RINGS OF LINGIN.
These rings of lingin allow the xylem vessel to withstand the pressure changes as water moves throughout the plant.
Transport of water through the plant - into the leaves
When water reaches the leaves it is used by the cells in the leaves for photosynthesis.
The cells which photosynthesise are in the palisade mesophyll layer.
The rest of the water evaporates through the tiny holes in the lower epidermis called the stomata.
What is the process of transpiration?
Transpiration is the movement /loss of water throughout the plant.
Water evaporates from the stomata in the leaf. This causes water pressure changes within the plant meaning more water is drawn into the roots and up through the xylem into the leaves to replace it.
The faster water evaporates from the leaves, the faster water is absorbed through the roots to replace it (due to the pressure changes).
Factors that affect transpiration
Speed up transpiration:
Wind speed
Temperature
Leaf surface area
Slow down:
Humidity
The transport of sugar through a plant
PHLOEM carries dissolved sugar from the leaves to the rest of the plant.
Phloem cells have SIEVE plates (cells) and COMPANION cells to allow sugar to be transported to all parts of the plant.
The cells is the phloem are alive and the end walls form sieve plates.
Companion cells provide the energy for the sieve plates. The end walls of the sieve cells have pores through which sugar is transported from cell to cell.
Xylem cells
Cells are dead and form a hollow tube. It is strengthened by rings of lignin.
Xylem cells carry WATER from the roots to the leaves.
Phloem cells
Phloem cells are alive and the end walls form sieve plates.
Phloem cells are made of 2 types of cell
- sieve
- companion
The phloem carries SUGAR from the leaves to the rest of the plant.
Pathogens
Pathogens are disease-causing microorganisms.
Example - bacteria, viruses, fungi
Types of white blood cells
Lymphocytes
Phagocytes
Phagocytosis
Phagocytosis is the process by which phagocytes will ENGULF and digest the pathogen.
Phagocytes carry out the process of phagocytosis by ENGULFING the pathogens.
Phagocytosis stages/process
1) the phagocyte moves towards the pathogen
2) its flexible membrane surrounds the pathogen and engulfs it.
3) it releases enzymes onto the pathogen to digest it.
Lymphocytes and pathogens
When a lymphocyte detects a pathogen it produces proteins called antibodies.
The antibodies attach onto the ANTIGEN on the surface of the pathogen.
Each pathogen has its own unique antigens so the antibodies are specific to the antigen.
Label heart structures and coronary arteries
In jotter
Draw
Functions of the heart - atria
(Atria - L/R atrium)
Pump (deoxygenated) blood into the ventricles
Functions of the heart - ventricles
L/R ventricle
Pump (oxygenated) blood out of the heart
Functions of the heart - vena cava
Carries deoxygenated blood from the body into the right atrium.
Functions of the heart - pulmonary vien
Carries oxygenated blood to the left atrium from the lungs.
Functions of the heart - pulmonary artery
Carries deoxygenated blood from the right ventricle to the lungs.
Functions of the heart - aorta
Carries oxygenated blood from the left ventricle to the rest of the body (except the lungs).
Functions of the heart - heart valves
The chambers of the heart are separated by valves to prevent the backflow of blood into the heart.
Functions of the heart - coronary arteries
Supply the heart muscle with oxygenated blood
And also glucose and amino acids.
What happens if the coronary arteries became blocked?
The heart is a muscle and requires oxygen to function.
Blockage of the coronary arteries can deprive part of the heart muscle of OXYGEN.
This is called a heart attack.
Pathway of blood around the body
Deoxygenated blood enters the right side of the heart through the vena cava and enters the right atrium. It is pumped into the right ventricle and is pumped out of the heart through the pulmonary artery to the lungs.
Oxygenated blood returns from the lungs to the left side of the heart, it enters through the pulmonary vein in to the left atrium. It is pumped out of the left atrium into the left ventricle and out of the left side of the heart to the rest of the body through the aorta.
Arteries function and structure
Arteries take oxygenated blood away from the heart to the rest of the body.
Arteries have a narrow internal diameter (small lumen) and thick muscular walls to be able to carry the high pressure blood. The walls are elastic.
Note: the pulmonary artery carries deoxygenated blood to the lungs.
Viens function and structure
Carries deoxygenated blood under low pressure from the capillaries and return the blood to the heart.
The vien had thinner muscular walls than arteries and have a wider internal diameter (larger lumen).
Viens contain valves to prevent the backflow of low pressure blood.
Capillaries function and structure
Capillaries form networks at organs and tissues to allow efficient exchange of materials.
Capillaries have a large surface area and form a dense capillary network.
They are only 1 cell thick to allow a fast exchange of substances between the blood and body tissues.
Blood and tissues functions
Oxygen and nutrients from food must be absorbed into the bloodstream to be delivered to cells for respiration.
Waste materials must be removed from cells into the bloodstream.
Tissues contain capillary networks that allow the exchange of materials to a cellular level.
What increases the absorption of materials?
Surfaces involved in the absorption of materials have certain features in common:
- large surface area
- thin walls
- large blood supply
These increase the efficiency at which materials are absorbed.
Function of lungs
The lungs are gas exchange organs.
They consist of a large number of alveoli.
Oxygen into the blood is exchanged for carbon dioxide out of the blood.
Adaptions of our lungs for gas exchange - alveoli
Alveoli have a large surface area, thin walls and a good blood supply for more efficient diffusion of gases.
Many alveoli creates a large surface area.
Capillaries network creates a huge blood supply.
Adaptions of our lungs for gas exchange - alveolus and capillary
Walls of alveolus and capillary are 1 cell thick.
Adaptions of our lungs for gas exchange - cartilage
Rings of cartilage keep the main airways (trachea and bronchi) open.
Mucus traps dirt and microorganisms and cilia moves it up and away from the lungs.
Where are nutrients absorbed into the blood?
Nutrients from food are absorbed into the blood in the small intestine.
The small intestine contains a large number of thin walled villi to provide a large surface area for this absorption.
Absorption of materials: small intestine
At the small intestine, digested food is taken out of the gut and passes across the wall and into the blood.
To aid absorption of glucose (digested carbohydrate) and amino acids (digested proteins) villi have:
- thin walls
- a large surface area (as there are many villi)
- a good supply of blood
The laterals absorb fatty amino acids and glycerol (the products of fat digestion).
Villi
The network of BLOOD CAPILLARIES within the villi absorbs GLUCOSE and AMINO ACIDS.
The LACTEALS absorbs FATTY ACIDS and GLYCEROL.
