Unit 2 Exam Cards Flashcards
Which structures are present in prokaryotic cells?
- Slime layer
- Plasmids
- Circular DNA
- Pili
- Cell wall
When an egg cell becomes fertilised, what is it called?
Zygote.
Which type of cell has the potential to give rise to any type of cell?
Totipotent cells.
Which type of stem cell is found in the blastocyst, which can give rise to most types of cell apart from extra-embryonic cells?
Pluripotent cells.
Suggest some problems of using stem cells taken from another adult to treat disease.
- Risk of pathogens from the donor
- Risk of rejection
- Risk of abnormal growth/cancer
Which structure within cells modifies proteins?
The Golgi apparatus.
Define the term tissue.
A group of specialised cells with the same origin that perform a common function.
Outline the function of xylem.
- Transport of water
- Transport of minerals
- Structural support
Describe the structure of a cellulose microfibril.
- Cellulose made of beta glucose
- Glucose molecules joined by 1-4 glycosidic bonds formed through condensation reactions
- Glucose molecules in a straight chain
- Microfibril composed of many cellulose molecules
- Cellulose molecules held together by hydrogen bonds
Define the term species richness.
The number of species in a habitat.
Explain what is meant by the term genetic variation.
The variety of alleles in a gene pool.
Explain why it is better to store seeds rather than keeping fully-grown plants for long term conservation.
- Seeds are smaller, so more can be stored
- Seeds can remain dormant for a long time
- Seeds do not require the maintenance of fully grown plants
- Greater genetic diversity if a large number of seeds are stored
Suggest why seeds in seedbanks are stored at low temperatures in a dry atmosphere.
- Seeds less likely to germinate
- Reduces enzyme activity of micro-organisms
- Decreases the rate of decomposition
Explain the term antimicrobial properties.
The property of being able to kill micro-organisms.
Why must Petri dishes be sterile when the agar is poured into them?
To prevent the contamination of other bacteria and competition between the bacteria.
Explain why Petri dishes must not be completely sealed with tape before incubation.
To prevent anaerobic conditions which could encourage the growth of pathogenic bacteria. The bacteria in the culture also require oxygen for respiration.
Define the term endemic species.
A species which is restricted to one geographical area.
How do zoo breeding programmes help conserve rare species?
- Protects the species from predators or poachers
- Use of studbooks
- Processes like IVF used for breeding
- Wild behaviour reinforced for reintroduction into wild
- Reintroduced into reserves
Which ion is used for the production of chlorophyll in plants?
Magnesium ions.
Which ion is a component of the primary cell walls in plants?
Calcium ions.
What are nitrate ions used for in plants?
Provides nitrogen for the construction of vital molecules.
Explain what is meant by the term haploid number of chromosomes.
Half the number of chromosomes found in somatic cells.
Explain what is meant by the term gene locus.
The position of a gene on a chromosome.
What is the role of rough endoplasmic reticulum in a cell?
Proteins produced by the ribosomes on the outer surface are transported through the ER to other parts of the cell by vesicles.
What is the role of the Golgi apparatus in a cell?
Vesicles containing proteins from the rER fuse with the Golgi apparatus, which modifies the proteins .
How do stem cells become specialised?
- Stimulus (chemical) activates certain genes in the stem cell
- Only the active genes are transcribed
- mRNA is only made at the active genes
- Proteins are made from the mRNA which determine the structure and function of the cell
How is acrosin released from the acrosome?
- Chemical stimulus causes the acrosome to swell
- Vesicles fuse with the sperm cell membrane
- Exocytosis releases acrosin from the acrosome
Suggest why organs are considered more complex than tissues.
- Made up of tissues
- Made up of many different cell types
- Often have more than one function
Give two roles of the cell cycle.
- Growth
- Asexual reproduction
How could you distinguish between a cell in metaphase and a cell in anaphase?
Metaphase:
- Chromatids at equator of cell
- Chromatids attached
- Centromere complete
Anaphase:
- Chromatids seperated
- Centromere split
- Spindle fibres shortening
