N5 Biology Unit 2 Multicellular Organisms

What controls glucose levels?

The hormones Insulin and Glucagon

Mitosis

Provides new cells for growth and repair of damaged cells and maintains the diploid chromosome complement

Steps for Mitosis

1. Chromosomes shorten and thicken. Chromosome double.

2. Nuclear membranes break down. Chromosomes line up at the equator.

3. spindle fibres attach each centromere to a pole. The spindle fibres shorten and separate chromatids.

4. Nuclear membranes reform. Cytoplasm divides. Two identical daughter cells are formed.

What is a chromosome?

Lengths of DNA. Humans have 23 pairs.

What is a gene?

A section of a chromosome which codes for a protein.

What is a specialised cell?

Each have a particular structure for a specific job e.g. red blood cell

What are tissues?

A group of specialised cells that works together for a particular function e.g. the blood

What is an organ?

A structure made of a group of tissues working together to preform a function e.g. heart

What is a system?

A group of organs working together

What do stem cells in animals do?

Unspecialised cells which can divide to make more stem cells or become specialised.

What are embryonic stem cells?

Found in embryos at a very early stage

What are tissue stem cells?

Found in the body throughout life

What is specialization in animals?

Leads to the formation of a variety of cells

What is the nervous system made up of?

brain, spinal cord, nerves

What is the CNS?

Brain and spinal cord

What does the cerebrum do?

Controls memory and conscious thought

What does the cerebellum do?

controls balance and coordination

What does the medulla do?

Controls heart rate and breathing rate

What are sensory neurons?

Pass information to the CNS from a sense organ/receptor

What is an inter neuron?

Pass through information from sensory receptor to the CNS or straight to the Motor Neutron

What are motor neurons?

Enable a response to occur at an effector(muscle or gland)

What is a receptor?

Detect sensory input/stimuli

What carries messages along neurons?

Electrical impulses

What carries messages between neurons?

Chemical messages through synapses

What is a reflex action?

A rapid automatic response to a stimuli which protects the body from harm e.g. blinking, removing hand from hot object

What is the reflex arc?

Sensory Neuron --> Inter Neuron --> Motor Neutron

What are hormones?

Chemical messengers

Where are hormones made?

Endocrine glands

What does a endocrine gland do?

Release hormones into the blood stream e.g. Pancreas, testis, ovaries

What is target tissue?

Has cells with complimentary receptor proteins for specific hormones, so only that tissue will be effected by that hormone

What is glucose needed to make?

ATP

What is glucose stored as?

glycogen

Insulin steps

1. High glucose levels in the blood (after a meal)

2. detected by pancreas and produces more insulin (endocrine gland)

3. Insulin travels in blood to liver. Liver stores glucose to glycogen. (Target tissue)

4. Blood glucose levels go down

Glucagon steps

1. Low glucose levels in blood (after exercise)

2. Pancreas detects and produces more glucagon. (endocrine gland)

3. Glucagon travels in the blood to liver. Liver converts glycogen to glucose. (Target tissue)

4. blood glucose increase.

Sperm

Male gamete in animals

Ova

Female gamete in animals

Diploid

A cell containing two copies of every chromosome

Haploid

A cell containing one copy of every chromosome

Testes

Produces sperm cells

Ovary (animal)

Produces egg cells

Pollen

Male gamete in plants

Ovule

Female gamete in plants

Anther

Produces pollen

Ovary (plant)

Produces ovules

Fertilisation

The fusion of the nuclei of the two haploid gametes

Zygote

Cell produced by fertilisation

Continuous variation

A wide range of values between two extremes e.g height (polygenic inheritance)

Discrete variation

There are distinct groups with no values in between e.g. eye colour (single gene inheritance)

Polygenic inheritance

A trait that is controlled by more than one gene

Variation

Differences between individuals. Can be inherited or due to environmental pressures

Allele

Different types of the same gene

Phenotype

The appearance an organism has

Genotype

The combination of alleles an organism has

Homozygous

Two copies of the same allele in genotype e.g. AA or aa

Heterozygous

Two different alleles in genotype e.g. Aa

Dominant

The allele which always shows in the phenotype

Recessive

The allele which can be hidden in the phenotype

What is the Predicted phenotype ratio?

Often the actual ratio of phenotypes in offspring are different from predicted one because fertilisation is a random process

Roots (plant organ)

Have a large surface area to absorb water and minerals. Water enters root cells by osmosis. Water moves into the cell down a concentration gradient.

Xylem

Carries water and minerals through the plants. Made of dead tissue supported by ring of lignin.

Lignin

Helps the xylem to withstand the pressure changes as water moves through the plant.

Phloem

Transports sugar (glucose) up and down the plant. Made of living cells. Has a companion to provide energy and a sieve plate.

Stomata (leaf)

Holes in the leaf controlled by guard cells which allows CO2 in and oxygen + water out

Guard cells (leaf)

Controls opening/closing of stomata

Veins (leaf)

Made of xylem

Palisade mesophyll

Contains chloroplasts for photosynthesis

Spongy mesophyll

Allows gas exchange

Gas transport (in plants)

Gassed enter and exit pants through stomata.

Transpiration process/steps

1. Water in soil

2. Water enters root hair cells by osmosis

3. Transported in xylem vessels

4. Evaporated through stomata

Direction of blood flow

Lungs -> (pulmonary vein -> LA -> LV -> aorta ->) body -> (vena cava -> RA -> RV -> pulmonary artery) -> lungs

Traits of an arteries

Thick and muscular vessel wall. Narrow central channel. High pressure of blood. Blood flow away from heart.

Traits of capillaries

Thinnest Vessel wall. Narrowest central channel. Blood pressure lower than arteries. Blood flow through tissues(from arteries and veins)

Traits of veins

Vessel wall muscular and thinner than arteries. Central channel wider than arteries. Lowest blood pressure. Blood flow toward heart.

What is blood made of and what does it do?

Blood contains plasma, red blood cells and white blood cells. Transports nutrients, oxygen and carbon dioxide.

Traits of Red blood cells

Red blood cells carry oxygen.

Specialised: biconcave in shape, no nucleus, contains haemoglobin; transports oxygen as oxyhaemonglobin

Traits of White blood cells

White blood cells are part of the immune system and are involved in destroying pathogens. Phagocytes and Lymphocytes

Phagocytes

Carry out phagocytosis by engulfing them digesting pathogens.

Lymphocytes

Produces antibodies which destroy pathogens. Each antibody is specific to a particular pathogen.

What's absorbed into the bloodstream?

Oxygen and nutrients (from foods)

Features of surfaces for absorption

1. Large surface area

2. Thin walls

3. Extensive blood supply (capillary networks)

Villi

Found in small intestine. Absorbed nutrients from food. Has a network of capillaries to absorb glucose and amino acids. Has a lacteal to absorb fatty acids and glycerol.

Waste materials

E.g. CO2. Must be removed form cells into the bloodstream.

What is single gene inheritance.

A trait which is controlled by only one gene.

What is absorbed by the lacteal?

Glyercol and fatty acids