BSC 2011 MIDTERM

Symplesiomorphy

shared ancestral trait (homologous)

synapamorphy

shared derived trait (homologous)

Horizontal gene transfer

Exchange of genes between organisms

Homoplasy

shared trait from independent evolutionary origin (analogous)

Where do trees get their mass from?

The air

What are some of the advantages of developing pollen?

- Ability to move large distances to cross fertilize another plant - Independence from water

Which of the following adaptations were key in allowing bryophytes to colonize terrestrial environments?

- Associating with fungi to increase nutrient absorption - A water tight cuticle to prevent water loss

What are some of the ways increases in CO2 affect plants?

- CO2 directly fertilizes plants increasing photosynthesis - Sea level rise can increase the salinity of wetlands - Climate changes modify the temperatures and water in plant habitats

Which molecular forces are more important for phloem transport?

- Changes in turgor pressure caused by osmosis - Changes in solute concentration

What are some of the advantages of asexual reproduction?

- Clone phenotypes that are well adapted to area - Fast reproduction to cover new open area - Large amounts of offspring produced

What is true about the apical meristems?

- Cluster of undifferentiated cells that give rise to many types of cells - Analogous to stem cells in animals - Responsible for growth in length of branches and roots - Responsible for primary growth

Which of the following structures contribute to the reduction of water loss in a leaf?

- Epidermis covered with waxy cuticle - Stomata located on the underside of the leaf

Why were fungi so important in the colonization of land by all plants?

- Fungi helped early plants obtain nutrients from soil similar to current mycorrhizae - Fungi formed lichen associations that helped break down rocks into soil

What causes stomata to open?

- Guard cells become turgid - Increased concentration of solutes in guard cells

What are some of the advantages of having flowers?

- Increased efficiency of pollination - Animals can be recruited to help transport pollen

What are some of the advantages of having fruits?

- Increased protection of embryos - Embryo can reach distant locations - Animals can be recruited to disperse seeds

Functions of seeds

- Plant dispersal - Nourish the embryo - Embryo protection

Which of the following adaptations are present in ferns and allowed them to colonize terrestrial environments?

- Presence of true roots for support and transport - Specialized vascular tissue made of tracheids

Which of the following is common to angiosperms and gymnosperms?

- Produce seeds - Water not required to carry sperm to egg - Dominant sporophyte generation

What is true about the lateral meristems?

- Responsible for secondary growth and width of branches and roots

Why are fungi ecologically important?

- Some can ferment and produce bread, beer, wine, cheese, and soy sauce - They break down lignin - Cause disease in plants and animals - Break down organic material and return them to the ecosystem

Which of the following is common to ferns and mosses?

- Spores are their main mean for dispersal - Water is required to carry the sperm to the egg

Functions performed by ground tissue

- Structure support - Food storage - Photosynthesis

During phloem transport, which of the following occur at, or close to the sink?

- Sugars move out of sieve tubes by active transport - Water moves from phloem into xylem - Turgor pressure decreases

What are some of the advantages of having seeds?

- The embryo can move and colonize new areas - The embryo is protected from drying out - Provide the embryo with nutrient reserves to start development

What are some of the disadvantages of seedless plants?

- The embryo cannot move and colonize new areas - The embryo will dry out if removed from the gametophyte

What is true about the phloem?

- Transports sugars from the leaves to any part of the plant - Formed of live cells - Uses active transport to move sugars and amino acids

What is true about the xylem?

- Transports water and nutrients from roots to the rest of the plant - Can derive from primary and secondary growth - Relies only on passive transport such as water potentials - Formed of dead cells (tracheids and vessels)

Which of the following are adaptations to soils with low nitrogen?

- Trapping and digesting animals - Mycorrhizae - Associations with nitrogen fixing bacteria

What forces help trees move water up the xylem?

- Water molecules stick to eachother (cohesion), each molecule that evaporates pulls the next one - Water moves by osmosis from hypotonic areas. with low solute concentration into hypertonic areas -Water molecules have adhesion to the walls of tracheids and xylem vessels allowing them to form tall columns of water - Water molecules evaporating at the leaves pull other water molecules in the transpiration stream up

During phloem transport, which of the following occur at, or close to the source?

- Water moves from the xylem into the sieve tubes - Solution in sieve tubes becomes hypertonic - Sugars move into sieve tubes by active transport

How is an increase in herbivory related to CO2 levels?

- You have to consume more plant material in order to acquire the same amount of nutrients and protein - CO2 stimulates plant growth - Plants are growing faster and thus are accumulating fewer nutrients in their tissues

What are some of the advantages of having tracheids?

-Ability to transport water and nutrients greater distances - Provide structural support so the plant can grow taller

The path of a pair of electrons from a water molecule during the light dependent reaction

1. A pair of electrons is removed from a water molecule 2. Energy from photons is transferred to electrons via photosystem II 3. The cytochrome complex uses the energy in the electrons to pump protons 4. Energy from protons is transferred to electrons via photosystem I 5. Electrons are given to NADP+ forming NADPH

Phloem transport steps

1. At the source, sugars move from the leaves into sieve tubes by active transport 2. The solution in sieve tubes becomes hypertonic 3. Water moves by osmosis from the xylem into the sieve tubes 4. Turgor pressure makes fluid move from the source to the sink 5. Sugars move from the sieve tubes into their destination cells

Humans and mice share at least 85% of their genes. How can they look so different while being so genetically similar? A small genetic difference can result in a large morphological difference by

1. Changing the timing in which a body part starts to develop 2. Changing the location where a body part grows from 3. Changing the information by altering the gene sequence

Which of the following are main functions of photosystem I?

1. Collect energy from photons 2. Transfer energy from photons to the electrons

Plants synthesize their own food in the form of sugars during the process of photosynthesis. Which of the statements describe photosynthesis?

1. Convert carbon dioxide to sugar, releasing oxygen 2. Cellular process that occurs in the chloroplasts of plants 3. Produces sugar for the plant using energy from the sun

Steps of how life occurred

1. Earth formed 2. First life form appeared 3. Photosynthetic cyanobacteria 4. Oxygen levels rose 5. Eukaryotes appeared

Life cycle of plant steps

1. Fertilization 2. Zygote formed 3. Sporophyte develops 4. Spores produced by meiosis 5. Gametophyte develops 6. Gametes produced by mitosis

The hox paradox came from the early evo-devo studies, where the surprising data showed high degree of conversation in the hox genes despite the broad diversity of life forms. The following statements help explain this paradox.

1. Hox genes act as transcription factors and control the activation of other genes 2. Although hox genes are relatively unchanged, they may be activating a different set of genes in each animal 3. Small changes in the location or timing of the activation of a gene can have great effect on morphology

Why did alternative metabolic pathways such as CAM plants and C4 plants evolve?

1. In warm and dry environments plants have to close stomata to prevent water loss 2. CO2 concentration drops quickly when the stomata are closed 3. When there is low CO2 rubisco will bind to oxygen and instead of fixing CO2, it will release the CO2 that has already been fixed

What are some of the characteristics of adaptive radiation?

1. Organisms colonize new areas with low ecological competition 2. Higher rates of speciation as organisms adapt to new ecological roles 3. Involves groups of related organisms

How are prokaryotes different from eukaryotes?

1. Prokaryotes are unicellular, although they can form colonies 2. Prokaryotes don't have a nuclear membrane 3. Prokaryotes lack membrane-bound organelles

Which of the following are the main functions of photosystem II?

1. Release oxygen 2. Collect energy from photons 3. Transfer energy from photons to the electron 4. Remove electrons from water

What are some of the consequences of mass extinctions to life diversity?

1. Specialized predators and organisms at the top of the food chain disappear first 2. Adaptations that could be very beneficial may vanish 3. Multiple species or even taxa can vanish (reducing diversity)

Why do some people argue that we are heading into the 6th extinction?

1. The rate of declining populations will reach mass extinction rates 2. CO2 levels are increasing, similar to what was seen in previous extinctions, but at an even faster rate

In living organisms, the info is stored in the DNA, which is transcribed into RNA. The RNA is read by the ribosome to make proteins. Thus the flow of info in living organisms is DNA to RNA to protein. However, most viruses violate this order. Which of the following are examples of info flow unique to viruses?

1. Their RNA genome is used to make more copies of RNA for transcription. 2. Their RNA is reverse transcribed into DNA by reverse transcriptase.

Viruses are very simple. Most are composed of only genetic material inside a protein capsule. Which of the following best explain why viruses are so simple?

1. They evolved from pieces of cellular DNA or RNA that were able to move between cells. 2. They evolved from cells that formed symbiotic relationships with other cells and overtime became simpler and more dependent on the host

Which of the following is true about light independent reactions

1. They need the products from the light dependent reactions 2. They don't need light directly

Bacteria can quickly evolve antibiotic resistance. Once one bacterium evolves the ability to survive an antibiotic, it can quickly spread to the other bacteria. Which mechanisms allow bacteria to exchange genetic information?

1. Transduction: when viruses infect a bacterium and insert DNA from another cell 2. Conjugation: when bacteria exchange DNA plasmids 3. Transformation: when bacteria intake DNA from the environment

Using isotope analyses of early fossils, the first living organism appeared on Earth about

3500 million years ago

Which of these are produced in the light dependent reactions and are necessary in the calvin cycle

ATP and NADPH

When life first appeared, the atmosphere had no oxygen. Thus, you can expect that the first living forms were

Anaerobic, using inorganic substances for energy and food

Why do the same pair of electrons receive energy from photons at photosystem II and photosystem I?

Because some of the energy is used to create a proton gradient

Which of the following explains why plants produce compounds such as caffeine?

As a defense against herbivores

Which of the following indicate conditions in which the stomata will close?

At midday in hot and dry environment

How do CAM plants fix CO2?

At night, the stomata are open and PEP carboxylase fixes CO2 into other organic compounds. In the day, these molecules are broken down to release CO2

Hormone that stimulates growth and bending in response to light and gravity

Auxin

Which of the following describes the phylogenetic relationships between the three domains?

Bacteria is the most ancestral domain, followed by archaea then eukarya

Why can't you treat viruses with antibiotics?

Because viruses aren't cells

Which of the following is FALSE about plant secondary compounds?

Beneficial to herbivores

Which of the following is common to bacteria and archaea?

Both lack a nucleus surrounding the DNA

Which of the following is true about carbon dioxide levels?

Carbon dioxide fluctuates but has recently sharply increased

A bacterium that causes disease that breaks down human tissues for energy and carbon source would be considered a

Chemoheterotroph

Some bacteria are very important for agriculture. They use nitrification, converting ammonia into nitrate, which can be used by plants. These bacteria use inorganic nitrogenous molecules for energy and inorganic carbon dioxide as a carbon source. Nitrifying bacteria are considered

Chemolithoautotroph

Sexual reproduction is the process of recombining genetic information between the parents to produce offspring. In prokaryotes, it's said that they have sex without reproduction and reproduce without sex. What do we mean by bacteria having sex without reproduction?

Conjugation, transduction, and transformation

Vertical gene transfer

Copying of genes from parents to offspring

What is the main function of flowers?

Cross pollination

Hormone that stimulates plant cell division in shoots and roots

Cytokinins

Hormone that regulates fruit rippening

Ethylene

What is the fate of most of the water that trees absorb from the roots?

Evaporates at the leaves

Why can't the Calvin cycle happen at night?

Even if it doesn't need light directly, it still needs constant supply of the products of the light dependent reactions

What two items are present in all viruses?

Genetic material and a protein capsule

How does one species split into two?

Geographical separation

What is the final destination of the electrons removed from water?

Glucose

Cells that form stomata opening

Guard cells

How does HIV cause death?

HIV attacks cells in the immune system, decreasing defenses to other infections

Chemolithoautotrophs

Harvest both energy and carbon from inorganic molecules

Chemoheterotrophs

Harvest both energy and carbon from organic molecules

Photoautotrophs

Harvest energy from light and obtain carbon from inorganic molecules

Photoheterotrophs

Harvest energy from light and obtain carbon from organic molecules

Which of the following will cause water to move into the cells in the roots of a plant?

High concentration of solutes inside root cells

How can you tell if two populations are different species?

If they cannot interbreed

Some antibiotics that are effective against gram positive bacteria have no effect on gram negative bacteria. What can explain this difference?

In gram negative, the outer cell membrane prevents antibiotics from reaching the cell wall

How do C4 plants fix CO2?

In the mesophyll cells, PEP carboxylase fixes CO2 into a 4 carbon compound, which is then transported into the bundle sheet cells and broken down to produce CO2

What is the main advantage of outcrossing (sexual reproduction)?

Increase in genetic variability

Virus

Infectious agent made of at least some form of genetic material and a protein capsid. Can infect multiple organisms, from bacteria to humans.

Prion

Infectious agent responsible for several neurodegenerative diseases found in mammals that consist of protein, with no nucleic acid genome

RNA likely played an important role in life's origins because

It can replicate itself

What did the Muller-Urey experiment show?

It proved that simple organic molecules, such as amino acids and nucleic acids, can be made by simple chemical processes possible under the conditions of early earth

What would happen if you take the gene that regulates eye development in mice and insert it into the back leg of a fruit fly?

It would grow a fruit fly eye on its back leg

The symbiotic relationship between green algae or cyanobacteria and fungi produces a

Lichen

In which of the following groups the gametophyte is the dominant form, the one we are more likely to encounter and see with our naked eye?

Liverworts and mosses

Some viruses can insert pieces of DNA from one bacterium into another. Viruses with which type of reproductive cycle are more likely to do this?

Lysogenic

The virus that causes shingles can remain dormant in nerve cells for decades then suddenly reemerges and starts to cause painful blisters. What type of cell cycle leads to this?

Lysogenic

Some viruses, like HPV, are associated with cancer. Nearly all cervical cancer is due to HPV. HPV is believed to cause cancer partly by integrating into the host DNA and causing DNA damage. This mechanism occurs when HPV reproduces via the

Lysogenic cycle

Viruses like the common cold and the coronavirus start to reproduce as soon as they enter a cell. What type of cell cycle do they follow?

Lytic

What is the purpose of the proton gradient created in the thylakoid?

Make ATP

The expression of mouse pax 6 in fruit flies (drosphilia) resulted in the formation of a fruit fly eye, not a mouse eye. Why?

Pax 6 is a control gene that activates genes from the drosphilia genome, which in turn have the instruction on how to make an eye

Cyanobacteria are related to the first organisms to have ever done photosynthesis. Some of these organisms are the ancestors of chloroplasts in plants. Photosynthetic bacteria changed the environment of the entire planet by releasing oxygen into the atmosphere. What would you call a bacterium that uses light for energy source and carbon dioxide for carbon source?

Photoautotroph

Where did the oxygen in the atmosphere come from?

Photosynthetic bacteria

Which of the following indicate conditions in which the stomata will open?

Plant needs to intake CO2

What are the male and female gametophytes in angiosperms and gymnosperms?

Pollen and ovule

Which of the following is the most likely plant response to an attack by herbivores ?

Production of chemical compounds for defense or to attract predators

Which of these molecules is more likely to have appeared first? RNA, DNA, Protein

RNA

Photosynthesis, the process and most of the enzymes needed, evolved in a time when the atmosphere had no oxygen. What problem has appeared now that oxygen makes up more than one fifth of the atmosphere?

Rubisco can bind to oxygen instead of carbon dioxide and release carbon dioxide

Why does salinity affect plant growth?

Salinity will change the osmotic balance of the plant in relation to the soil

The bladderwort of the genius Ulticularia is very common in the everglades. Bladderworts are carnivorous plants. What does this tell you about the nutrient conditions of the everglades?

Soil has low nitrogen

Which of the following is the first line of defense for plants?

Structural defenses such as thorns and waxy cuticles

Which of the following will result in a lower water potential so that water will move towards it?

The cell has higher concentration of solutes (hypertonic)

Virion

The complete, infective form of a virus outside a host cell, with a core of RNA or DNA and a capsid

A phylogenetic tree is a diagram that describes a phylogeny. What is a phylogeny?

The evolutionary history of a species or group of species

How can we know the age of a fossil?

The fraction of radioactive isotope in the fossil is related to its age (compare ratio of carbon 12 and carbon 14)

For some viruses, we can develop a vaccine that protect us for a lifetime. For other viruses, such as influenza, we need a new vaccine every year. What explains this difference in the effectiveness of the vaccine?

The rate of mutation and recombination of the virus

All apes lack a tail. However, monkeys, who share a more ancient common ancestor with apes have tails. What is the most parsimonious explanation for the lack of tail in apes?

The tail trait was lost in the most recent common ancestor of all apes

What is the most likely reason why plants evolved to release signals into the air?

To alert other parts of the same plant about herbivores

How do trees turn air into mass?

Trees convert carbon dioxide gas into solid glucose using energy from the sun

Starting with ferns all the way to angiosperms, these plants have __________ tissue that function to move water and nutrients from the soil to the leaves and sugars from the leaves to the rest of the plant

Vascular

Viroid

an infectious entity affecting plants, smaller than a virus and consisting only of nucleic acid without a protein coat.

What is the main function of fruits?

seed dispersal

Fungi are ________, they obtain both their energy and carbon from organic substances. Most fungi are ______________ helping break down organic matter from previous organisms and recycling those nutrients back into the soil

heterotrophs, decomposers