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intro biology 2024 s1 > Organisms Development > Flashcards

Organisms Development Flashcards

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AP® Biology flashcards
1
Q

overview of embryogenesis in plants

A
  • zygote
  • undergoes asymmetrical division to produce the 2-cell stage
  • 2 cell stage has an apical and basal daughter cell (basal produces suspensor, apical produces embryo)
  • 2 cell stage undergoes a series of oriented divisions to produce the octant stage
  • the octant undergoes cell expansion to produce the heart stage
  • the heart stage has the shoot apical meristem at the top of the cotelydon primordia (between the two outgrowths) and the root apical meristem at the base of the cotelydon primordia
  • the heart stage further differentiates, elongates and grows into the torpedo stage
  • the torpedo stage then further develops into a mature embryo (which has a seed coating)
  • then organogenesis occurs (creation of the organ systems of the plant along with further development of the tissues)
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2
Q

what is determination?

A
  • Establishment of cell fate (determination) arises during the early stages of embryogenesis
  • Cells become increasingly more restricted in their fate- change in cell potency
  • Cells may look superficially the same but the DNA that is expressed changes and therefore the cells will further differentiate
  • Pattern of cell fate is highly ordered and reflects the position of cells in the developing embryo
  • Progressive acquisition of cell fate is associated with the pattern of gene expression which is dictated by instructive cues from internal or external factors
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3
Q

what is morphogenesis? and examples

A
  • Morphogenesis
    ○ Process by which cells and tissues organise and arrange themselves to create the final form of the body
  • Including
    ○ Division
    ○ Changing shape (expansion)
    ○ Moving (not seen in plant embryogenesis)
    ○ Adhering to one another (not seen in plant embryogenesis)
    ○ Detachment
    ○ Death (apoptosis)
  • The establishment of cell fate, leads to an organised distribution of cells
  • This is done through morphogenesis
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4
Q

what is differentiation?

A
  • The final body is comprised of many types of specialised cells, which come together into coherent tissues, and organs that make up the functioning organism
  • They all contain the entire genome, however, they do not express the entire genome
  • They therefore have different properties and behaviour
  • This formation of different cell types is known as differentiation
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5
Q

Types of genes in development

A

○ Some genes are expressed in all cells (house-keeping genes)
○ Some genes are expressed in one cell type, but not another (cell-specific genes)- differential gene expression

e.g.
Tubulin is a part of the cytoskeleton and it is therefore formed by the expression of a housekeeping cell, as housekeeping cells are expressed in all cells as they are essential to cell function

Synapsin, is a protein found in the synapse of a neuron, and since this is a specialised cell with a specialised function, this protein isnt needed in every cell. Therefore it is produced by a cell-specific gene

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6
Q

Process of plant development

A
  • Morphogenesis
    ○ Orientated cell divisions
    ○ Expansion
    ○ No gastrulation
  • Body plan established
    ○ Apical/basal axis established- body plan established
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7
Q

animal development

A
  • Morphogenesis
    ○ Cell divisions more random (though can still be oriented)
    ○ Cell shape change
    ○ Cell movement
    ○ Cell adhesion (to form tissues) and de-adhesion
  • Body plan
    ○ Anterior/posterior axis established- body plan established
    Formation of segments
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8
Q

the post embryonic growth patterns of animals

A

○ Structures arising during embryogenesis
○ All organs and tissue types formed
○ From young to old there is a size different but not any other important bodily developments
○ This is determinant growth
§ Predetermined body form increase in size

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9
Q

post embryonic growth patterns of plants

A

○ Few organs and tissue types formed
○ A seedling has more organs and branching and complexity compared to an embryonic plant
○ They continue to develop and differentiate after embryonic development
○ This means they have a flexible body plan
○ Modules
§ Continual addition of new tissues and organs
○ Indeterminate growth pattern
§ Flexible body and an increase in sie
○ This is likely due an adaptation due to a sedentary lifestyle, unlike animals

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10
Q

How does evolution relate to development?

A
  • Genomic sequence control the cells
    • Variations therefore create variations in the body
    • In a species there are variations in genome which can then create subtle differences between cell development and therefore the organisms traits
    • Species evolve through these small differences
    • Small changes in DNA can cause large effects
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11
Q

Describe fertilisation

A

two gametes combine in order to produce a zygote

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12
Q

describe cleavage

A

the first cell (fertilised egg) undergoes rapid cell divisions called cleavages
this divides the zygote into smaller and smaller cells without a growth phase
it goes from a zygote, to a 2-cell stage, to the octant stage, and a couple more divisions until it reached the blastula
the blastula contains many undifferentiated cells surrounding a fluid filled cavity

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13
Q

describe gastrulation

A

gastrulation is the process where the body plan is established and whereby some cells move in the blastula move into the embryo

the anterior and posterior (up/down) and the dorsel/ventural axes (left/right) are established

the germ layers are established: endoderm, mesoderm and ectoderm are also established

this also causes an inwards bulge called invagination

at the end of this stage a gastrula is produced

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14
Q

what do each germ layer produce?

A
  • Ectoderm- skin and nervous system
  • Mesoderm- blood vessels, muscles, connectives tissue
  • Endoderm- lining of gut, lung etc.
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15
Q

describe the difference between a triploblast and a diploblast

A
  • Animals with three germ layers are triploblastic
  • Animals lacking a mesoderm have two germ layers and are called diploblastic
  • Diploblastic organisms
    ○ Endoderm and ectoderm only, no mesoderm
  • These include cridarians such as jellyfish and hydra
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16
Q

what are animal body plans?

A
  • Body plan = general structure of an organisms, arrangement of organ systems, integrated functioning of its parts
    Body plants can be categorised according to symmetry, body cavity structure, segmentation, type of appendages, and type of nervous system
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17
Q

what is radial symmetry?

A

any plane along the central body axis divides the animal into similar halves

diploblasts

e.g.
straight down the middle of a tree

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18
Q

what is bilateral symmetry?

A

a single plane through the anterior-posterior midline divides the animal into mirror-image halves

triploblasts

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19
Q

How do new cells arise?

A
  • In some tissues in the body, cells die and need to be replaced
  • New cells come from the division of stem cells- undifferentiated cells that can divide indefinitely
  • A stem cell division produces a new stem cell and a daughter cell that can subsequently differentiate into other cell types
  • Self-renewing undifferentiated cells- STEM CELLS
  • Following the division, one remains as a Stem cell and the other cell differentiated in order to maintain the same quantity of stem cells needed
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20
Q

what is stem cell potency and what are the 4 types?

A
  • The ability of a cell to give rise to other cell types is called its potency
  1. totipotent
  2. pluripotent
  3. multipotent
  4. unipotent
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21
Q

what is totipotent?

A
  • Totipotent
    ○ Potential to produce all cell types of an organism (e.g. zygote)
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22
Q

what is pluripotent?

A
  • Pluripotent
    ○ Can produce all the cell types of the body but not cells of extraembryonic tissues like the placenta (e.g. embryonic stem cells, and induced pluripotent stem cells)
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23
Q

what is multipotent?

A
  • Multipotent
    ○ Can produce several cell types (e.g. intestinal stem cells)
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24
Q

what is unipotent?

A
  • Unipotent
    ○ Can only produce one cell type
    ○ i.e. cells that can only produce daughter cells of the same type (e.g. skin cells)
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25
Q

describe the root system and their purpose

A
  • differentiate from the root apical meristem
  • produces the fibrous/tap root, which is the main root
  • from this stems the hair roots which are the main points of growth
  • they contain the root caps, which protect the roots from the soil

purpose:
- water and other soil-derived nutrients are taken up by the roots to be delivered to the rest of the plant
- the water is transported through the symplastic or apoplastic pathways in the roots and are then delivered to the xylem to be transported to the rest of the plant
- water diffuses into the cells of the root and then are transported through cells in the symplastic pathway, using plasmodesmata, tubes that act like pipes connecting the cell. Cells regulate this process
- the apoplastic pathway is the travel of water in the intercellular space from an area of high water concentration to an area of low water concentration, therefore transporting the water to the xylem

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26
Q

root apical meristem tissues and zones

A
  • In the root apical meristems
    ○ Zone of cell differentiation
    § Cells differentiate into distinct types
    ○ Zone of cell elongation
    § New cells lengthen and extend the root tips
    ○ Zone of cell division
    § Root apical meristem
27
Q

describe the shoot apical meristem differentiation

A

○ Primary meristems- protoderm (dermal tissue)
○ Ground meristem- ground tissue (incl. pith and cortex)
○ Procambium- vascular tissue, xylem and phloem

28
Q

describe the structure of a leaf

A
  • Most leaves are flat and thin and have a distinct upper and lower region
    • It has an extensive network of veins as a part of the vascular system
    • Parenchyma tissue- photosynthetic has 2 types of cells
      ○ Upper palisade layer- 1 layer or more
      ○ Elongated cells where most of photo occurs
      ○ Mesophyll cells- irregularly shaped cells arranged so that there is a lot of air in the lower section of the leaf
    • Veins are also a part of the leaf and are a part of the vascular tissue
    • Bundle sheath cells- also parenchyma- surrounds vein and facilitates the transfer of nutrients from the veins to the leaf
    • Epidermal tissue- protective layer and non-photosynthetic
29
Q

what is the xylem

A

dead, hollow elongated cells
transport water from roots to shoots of a plant
have angular and spiral lignin to do this
transpiration alongside the cohesion and adhesion properties of water create tension and pressure gradient causing water to rise (transpiration pull)

30
Q

what is the phloem

A

living vasular tissues
sieve tube cells
- transport the water and nutrients
- have large open pores like sieves (plasmodesmata)
- have no nucleus and very little structure

sieve cells are therefore surrounded by companion cells
- assist sieve tube cells in remaining functional despite their lack of cellular structures

31
Q

what is primary and secondary growth in plants

A

Primary growth
○ Extend shoots (light) and roots (soil nutrients)
Secondary growth
○ Structural support, to support the lengthening of woody plants

32
Q

decribe embryogenesis in animals

A
  • 2 gametes combine to form a zygote
  • undergo rapic cell divisions and cleavage (cells divide)
  • forms the 2 cell stage
  • further divisions produce the octant stage
  • further divisions produce the blastula (cells surrounding a fluid sack)
  • undergoes gastrulation where the blastula turns into a gastrula with 3 distinct germ layers and invaginates
  • it also develops the anterior/posterior and dorsal/ventral axes
  • the three germ layers are the ectoderm, medocerm and endoderm
  • this then further differentiates into a mature embryo
33
Q

describe the evolution of the circulatory system

A

fish
- 2 chambered heart
- gas exchange with water
- single circuit circulatory system

amphibians
- 3 chambered heart (2A + 1V)
- gas exchange with air
- partial double circuit
- pulmonary and systemic circuit
- deoxygenated and oxygenated blood mix
- low blood pressure

birds/mammals
- 4 chambered heart (2A +2V)
- gas exchange with air
- double circuit circulatory system?
- deoxygenated and oxygenated blood dont mix
- low blood pressure in veins, high blood pressure in artieries
- systemic, pulmonary and coronary circuits

34
Q

how does the circulatory cycle work?

A
  • Cardiac cycle
    ○ Coordination of contraction (systole) and relaxation (diastole)
    • An electrical signal sent from the sinoatrial node, near the right atria, causes both atria to simultaneously contract and push blood into the ventricles
    • When the pulse reaches the atrioventricular node (between the right atria and ventricle), it pauses for 1/10 of a second, which allows blood to completely empty from the atria
    • The charge spreads through the bundle of His and through intraventricular septum down through the right and left bundle branches and through the walls of the ventricles through Purkinje fibres
    • Inducing ventricular contraction and pumping the blood into the pulmonary artery and aorta
    • Whilst this occurs, the atria, which are in diastole, continue to be filled with blood
    • As the ventricles relax, the blood moves into them and the cycle continues
35
Q

what are the main veins and arteries and where do they go?

A

○ Carotid artery- brain
○ Brachial- arms
○ Thoracic- trunk and gut
○ Iliac- legs

veins:
○ Jugular vein- brain and head
○ Superior vena cava- upper body parts
○ Inferior vena cava- lower body parts

36
Q

what is translocation?

A

when the phloem transports nutrients and water from sources to sinks
nutrients in the phloem sap travels down the conc gradient from the source, which has a high conc, to the sinks, which have a low conc
water travels from positive water potential to negative water potential through osmosis into phloem

37
Q

what is primary growth in plants

A
  • Branching- primary growth
    ○ Lateral shoots/branches grow from axillary buds on the plants surface
    ○ Hormonal signals inhibit axillary buds (dormant) and shoot apical meristems (active)
    ○ This is called apical dominance
    ○ The removal of apical meristems disrupts apical dominance
    ○ This is how pruning encourages growth
    • Lateral roots
      ○ Originate from the pericycle
38
Q

what is seconday growth in plants

A

○ Two lateral meristems contribute to secondary growth
§ The cork cambium
□ Produces cork to the outside and phelloderm to the inside
□ Pericycle in roots origin
□ Cortex in shoots origin
□ Produces cortex and phelloderm
□ This all forms the periderm
§ The vascular cambium
□ Located between the primary xylem and the primary phloem

Secondary phloem and xylem/wood are developed from this

39
Q

what are the 4 tissue types in animals?

A

Connective tissue
Muscle tissue
Epithelial tissue
Nervous tissue

40
Q

what is epithelial tissue?

A
  • Epithelial tissue
    ○ Single of multiple cell layers
    ○ Cover external body parts
    ○ Line internal body surfaces
    ○ Form different glands
    ○ e.g. derma
41
Q

what is muscle tissue?

A
  • Muscle tissues
    ○ Specialised contractile cells
    ○ Facilitate body movement
    ○ Including
    § Smooth muscle
    § Cardiac muscle
    § Skeletal muscle
42
Q

what is connective tissue?

A
  • Connective tissue
    ○ Cells in a viscous matrix of extracellular fibre
    ○ Structural support
    ○ Transport nutrients
    ○ Fat reservoirs
43
Q

what is nervous tissue?

A
  • Nervous tissues
    ○ Neurons that respond to stimuli by responding to electrical signals
    ○ Help to coordinate various bodily functions
44
Q

what are cell to cell junctions?

A
  • Large multi protein complexes
    • Link cells to the extracellular matrixes forming cell matrix junctions
    • Act as contact points between neighbouring cells between tissues to form cell to cell junctions
45
Q

what are the 3 types of cell to cell junctions?

A
  • Typically have 3 main types of cell-cell junctions
    ○ Tight junctions
    ○ Anchoring junctions
    ○ Gap junctions
46
Q

what are tight junctions?

A
  • Tight junctions
    ○ Hold adjacent plasma membranes together
    ○ Act as a barrier for molecule flow
47
Q

what are anchoring junctions?

A
  • Anchoring junctions
    ○ Adherens junctions
    ○ Desmosome junctions
    ○ Work to form an interconnected cytoskeletal network that helps to resist mechanical forces
48
Q

what are gap junctions?

A
  • Gap junctions
    ○ Dispersed throughout the plasma membrane
    Communication between adjacent cells
49
Q

what are the two types of nervous tissue cell types and what do they do?

A

○ Two types of nervous cells
§ Neurons
§ Glial cells
○ Neurons transmit electrical signals called action potentials
○ Glial cells provide mechanical and nutritional support for neurons DO NOT generate action potentials
§ Schwann cells

50
Q

structure of a neuron?

A

○ Soma- contains the nucleus and most organelles
○ Dendrites- branching projections. Typically connected to other neurons or sensory cells and communicate
○ Axon- carry electrical signals in the form of action potentials away from the pre-synaptic cell towards the post-synaptic cell
○ Axon terminals
- Axon divides into many fine nerve endings that have axon terminals, come into proximity with the cell membrane of the receiving cell
- Swelling is the axon terminal
- The synapse is the gap between the pre and post synaptic cell

51
Q

skeletal muscle structure

A
  • Structure of skeletal muscle
    ○ Muscle is composed of bundles of muscle fibres (cells)
    ○ Muscle fibre
    § Multinucleate cells with many myofibrils
    ○ Myofibrils composed of highly ordered arrangements of myosin (thick) and actin (thin) filaments- striated appearance
52
Q

how do muscle contractions work?

A
  • Skeletal muscle is responsible for all voluntary movement
    • Myosin’s are able to use ATP to undergo movement that pulls the actin, resulting in them sliding past each other
    • Due to their arrangement, when contraction is triggered by an action potential, the sarcamere shortens the muscle is contracted
    • Muscle contraction is caused by an ATP-dependent motor protein comprised of myosin filaments pulling on actin filaments
    • Contraction is activated by electrical signals
53
Q

what is meristematic tissue and the 2 different types?

A
  • Meristematic
    ○ Considered regions of embryonic tissues capable of self-renewal and indefinite cell division
    • 2 types of meristematic tissue
      ○ Apical
      ○ Lateral
    • Apical meristem
      ○ Tips of roots and stems
      ○ Elongation
    • Lateral meristem
      ○ Increaase in the thickness or girth of the plants
      ○ Woody plants
54
Q

what is permanent tissue and its main types?

A
  • Permanent tissues
    ○ Terminally differentiated and can no longer divided
    • Class
      ○ Dermal
      ○ Vascular
      ○ Ground
55
Q

plant cell wall structure

A
  • Rigid structure located outside the plasma membrane which encloses the cell
    • Different layers
      ○ Middle lamella
      ○ Primary cell wall
      Secondary cell wall
56
Q

what is the middle lamella?

A
  • Middle lamella
    ○ Is the outermost layer of the cell wall
    ○ Lies between two cells- or in the middle of them- hence the name
    ○ Consists of pectin- allows cells to adhere to one another
57
Q

what is the primary cell wall?

A

○ Between middle lamella and secondary plant cell wall
○ As young plant cells divide, they secrete cellulose microfibres in a gel like matrix consisting of pectin and hemicellulose
○ Allows the plant cell wall to expand during cell growth
○ After it matures, it can deposit a secondary cell wall between the plasma cell membrane and the primary cell wall

58
Q

what is the secondary cell wall?

A

○ Thick and rigid cell wall
○ Cellulose
○ Hemicellulose
○ Lignin- hardening agents
○ Woods and grasses have secondary cell walls with lignin
○ However, woodier tissue cells, tend to have more secondary cell wall mass to provide more strength and rigidity
○ In an organism, the proportion and composition of secondary cell walls can change

59
Q

4 layers of tissue in the heart

A
  • 4 layers of tissue
    ○ Epicardium (outermost)
    ○ Pericardium (surrounds the epicardium)
    ○ Myocardium (cardiac muscle cells, the majority of heart walls)
    ○ Endocardium (inside of the heart)
60
Q

valves of the heart

A
  • Valves
    ○ Connective tissue for unidirectional flow (atria ventricular separation)
    • There are 4 main values
      ○ Tricuspid valve- between right atrium and ventricle
      ○ Mitral valve- between left atrium and ventricle
      ○ Pulmonary valve (pulmonary artery)- semilunar valve
      ○ Aortic valve (aortic artery)- semilunar value
61
Q

why does water move out of capillaries?

A
  • Water moves out of the capillaries at the arterial end because of the high pressure, and as the pressure decreased through the capillary as it approaches the venule end of the capillary
62
Q

what impacts the process of water moving out and in the capillaries?

A
  • Water movement is the result of 2 forces
    ○ Solute potential- blood osmotic potential (negative to osmotic pressure)
    § Large proteins and solutes cannot leave the capillary therefore the osmotic pressure remains consistent
    ○ Pressure potential- hydrostatic pressure or blood pressure
    § Varies across capillaries, less towards the venule
    ○ These combine to form the overall water potential which determines the movement of water
63
Q

what is the process of water moving in and out of capillaries called? describe it

A

○ The movement of water into the interstitial fluid from the capillaries is called filtration
○ Fenestrations- holes where filtration occurs
○ The process where water moves back into the capillaries is called reabsorption
○ Not all water is reabsorbed this way and the rest is returned to the system through the lymphatic system

intro biology 2024 s1 (18 decks)

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