大阪大学大学院理学研究科生物科学専攻
２０２０年度入学試験問題
英語（２０１９年８月３日 １０：００－１２：００）
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【１】1/2【１】 "The Decline of Insect Representation in Biology Textbooks Over Time"をテーマに、教科書での昆虫に関する記述が減少傾向にあることを論ずる以下の文章を読み、問に答えよ。
Insects, as the majority of animal species, have a substantial impact on ecosystems andhuman society. However, (a)both insect representation and content related to insect–human interactions have declined over the past century, increasing taxonomic bias.
Taxonomic bias is the disparity between a taxon’s influence or biomass innature and society’s interest in or understanding of that taxon. Insects are widely
recognized as underrepresented in scientific research. The same bias occurs inintroductory biology textbooks. (b)Phillips and Landin found that vertebrates arepictured in more than 44% of images in animal diversity chapters, despite making up
just 3–5% of animal species. Insects, on the other hand, make up 60–70% of animalspecies, yet are shown in less than 23% of images. Dove analyzed depictions ofrainforests in books and websites targeting children and revealed multiple forms ofmisrepresentation. Most striking was that only 41 invertebrate species appeared inbooks and only 22 on websites, though the Amazon rainforest has at least 100,000
invertebrate species.
The lack of exposure to accurate and fully representative information cancontribute to the embedding of “alternative conceptions” that do not correspond with
scientifically accepted knowledge; (c)such conceptions can shape the lens through which
students perceive all subsequent knowledge, and can therefore impede progress inlearning. In social contexts, an underrepresentation of women in children’s literature has
long-standing societal impacts where gender roles and cultural stereotypes persist, andexposure to female professors in science positively correlates with female students’performance and continuation in the field. In the case of biology and biodiversity,
students of all ages lack an accurate concept of biodiversity, while educational materials
reinforce a bias against certain taxa.
Insects are crucial components of virtually every ecosystem, and they provide
a wide variety of “ecosystem services” such as pollination, decomposition, andpredation of pests, as well as serving as primary consumers in food chains. Moreover,【１】2/2
the high level of diversity among insects has resulted in all manner of physical andbehavioral adaptations, allowing them to serve as inspiration for a wide variety of areasof study, including agriculture, architecture, biomimicry, drug discovery, forensics,
polymer development, and psychology. Yet, most currently, commonly used textbooks
in introductory biology do not give insects the attention warranted by their abundanceand (d)relevance to human life.
The emphasis, or lack thereof, on certain topics in research and education
often reflects broader sentiments held by the public. Declines in natural history content
are indicative of the overall decline of the public’s engagement with nature. The loss ofinsect abundance and diversity is a worsening reality and a cause for great concern. To
prevent further loss, it is crucial to understand and implement the tools of formal
education to create widespread awareness and to change general attitudes toward
insects.
出典：American Entomologist 64, 252-257 (2018), doi: 10.1093/ae/tmy064 より改変
注釈：taxon: タクソン、分類群、disparity: 不均衡、vertebrate: 脊椎動物、depiction:描写、invertebrate: 無脊椎動物の、conception: 理解、考え方、pest: 害虫、
forensic: 犯罪科学、emphasis: 重点、強調、sentiment: 感情、気持ち
問１

下線部 (a) の傾向は、社会と自然との関わり方における、ある状況を反映したものであると、この文章は主張している。どのような状況であろうか。該当する 1 文を英語で書き出し、和訳せよ。

問２

下線部 (b) を和訳せよ。

問３

下線部 (c) を和訳せよ。

問４

下線部 (d)では、人間社会や生活に、昆虫の関わる事例があると述べている。それはどのような事例だろうか。本文の文脈に沿って、具体例を日本語で２つ述べよ。

【２】1/4【２】 以下の文章は、Howard C. Berg の “Random Walks in Biology（生物学におけるランダムウォーク）” より抜粋した文章である。この文章を読み、問に答えよ。

（ア）

Diffusion is the random migration of molecules and small particles arising frommotion due to thermal energy.
In order to characterize diffusive spreading, it is convenient to reduce the problem toits barest essentials, and to consider the motion of particles along one axis only, say thex axis, as shown in Fig. 1. The particles starts at time t = 0 at position x = 0 and executea random walk according to the following rules：
Rule 1) Each particle steps to the right or to the left once every t seconds, moving at
velocity ±vx, a distance d = ±vxt. For simplicity, we treat t and d as constants. In
practice, they will depend on the size of the particle, the structure of the liquid, and theabsolute temperature T.

Fig. 1 Particles executing a one-dimensional random walkstart at the origin, 0, and move in steps of length d, occupying
positions 0, ±d, ±2 d, ±3dd, ….

Rule 2) The probability of going to the right at each step is 1/2, and the probabilityof going to the left at each step is 1/2. The particles, by interacting with the molecules ofwater, forget what they did on the previous leg of their journey. Successive steps are
statistically independent. The walk is not biased.
Rule 3) Each particle moves independently of all the other particles. The particles
do not interact with one another. In practice, this will be true provided that thesuspension of particles is reasonably dilute.
（イ）

These rules have two striking consequences. The first is that the particles go

nowhere on the average. The second is that their root-mean-square displacement is【２】2/4
proportional not to the time, but to the square-root of the time. It is possible to establish
these propositions by using an iterative procedure. Consider an ensemble of N particles.
Let xi(n) be the position of the ith particle after the nth step. According to rule 1, theposition of a particle after the nth step differs from its position after the (n-1)th step by
±d：

()

()

xi n = xi n −1 ± δ .

(Eq. 1)

According to rules 2 and 3, the + sign will apply to roughly half of the particles, the –sign to the other half. The mean displacement of the particles after the nth step can befound by summing over the particle index i and dividing by N：

1 N
x n = ∑ xi n .
N i=1

()

()

(Eq. 2)On expressing xi(n) in terms of xi(n - 1), Eq. 1, we find()x n =1 N∑ x n −1 ± δ
N i=1 i={ () }
(Eq. 3)1 N∑ x n −1 = xi n −1 .
N i=1 i(())

The second term in the brackets averages to zero, because its sign is positive for roughly
half of the particles, negative for the other half. Eq. 3 tells us that the mean position of
the particles does not change from step to step. Since the particles all start at the origin,where the mean position is zero, the mean position remains (ウ). This is the first
proposition. The spreading of the particles is symmetrical about the origin.
How much do the particle spread? A convenient measure of spreading is theroot-mean-square displacement

x2 n

()

1/2. Here we average the square of thedisplacement rather than the displacement itself. Since the square of a negative number
is (エ), the results must be finite; it cannot be zero. To findx 2 n , we write xi(n) in()terms of xi(n-1), as in Eq. 1, and take the square：xi2 n = xi2 n −1 ± 2δ xi n −1 + δ 2 .

()

()()

(Eq. 4)

【２】3/4
Then we compute the mean,

x2 n =

1 N 2∑x n ,
N i=1 ix2 n =

1 N 2xi n −1 ± 2δ xi n −1 + δ 2
∑
N i=1

()

which is()()(Eq. 5){ (())}(Eq. 6)= x 2 n −1 + δ 2 .

()As before, the second term in the brackets averages to zero; its sign is positive forroughly half of the particles, negative for the other half. Since xi(0) = 0 for all particles i,x 2 0 = 0 . Thus,()x2 1 = δ 2 ,()x 2 2 = 2δ 2 , ….., and()x 2 n = nδ 2 . We conclude()

that the mean-square displacement increases with the step number n, theroot-mean-square displacement with the square-root of n. According to rule 1, theparticles execute n steps in a time t = nt ; n is proportional to t. It follows that themean-square displacement is proportional to t, the root-mean-square displacement to the(オ) t. This is the second proposition. The spreading increases as the square-root of thetime.
To see this more explicitly, note that n = t/t, so that()x 2 t = t / τ δ 2 = δ 2 / τ t,() ( )(Eq. 7)

where we write x(t) rather than x(n) to denote that x now is being considered as afunction of t. For convenience, we define a diffusion coefficient, D = δ 2 / 2τ , in units
cm2/sec. This gives us
x2 t() =(1).

(Eq. 8)The diffusion coefficient, D, (カ) the migration of particles of a given kind in a given
medium at a given temperature. In general, it depends on the size of the particle, thestructure of the medium, and the absolute temperature.

【２】4/4
問１

下線部（ア）を和訳せよ。

問２

下線部（イ）を和訳せよ。

問３

本文中の（ウ）〜（カ）にあてはまる適切な単語を以下から選べ。
（one, zero, d, t, regulates, characterizes, increases, drift, square-root,
root-mean-square, square, positive, negative）

問４

本文に即して問５

この文章につけるタイトルを以下の選択肢から選び、その番号を記せ。
＜選択肢＞

内を埋め、式（8）を完成せよ。

(1)

A： Random walk with drift
B： Life at low Reynolds number
C： Bacterial diffusion
D： One-dimensional random walk
E： No diffusion, no life.

問６

本文の内容と式（８）を参考にして計算を行い、以下の文章内のと(2)(3)に入る数値を求めなさい。

A particle with a diffusion coefficient of 10-410-5cm2/sec diffuses a distance x =cm (the width of a bacterium) in a time t =(2)sec. Itdiffuses a distance x = 1 cm (the width of a test tube) in a timet=

(3)

sec.

【３】1/1【３】 国際学会における口頭発表のスピーチ原稿を読み、問に答えよ。
（自分の紹介をしてくれた座長に対して）(a)ご紹介ありがとうございます。
(b)はじめに、このような素晴らしい学会で私たちの研究成果を発表する機会を与えてくださった主催者の方に感謝したいと思います。本日は、酵素 A によるタンパク質 B のリン酸化についてお話します。
A と B のタンパク質をそれぞれ大腸菌で大量発現させ、アフィニティカラムを使って精製しました。(c)これらの精製した A と B を用いて試験管内リン酸化アッセイを行いました。このグラフの横軸は反応時間、縦軸は B のリン酸化レベルを示しています。 (d)この結果から、B は A の良い基質であることが示唆されました。今後、細胞内で実際に A が B をリン酸化しているのかどうか調べていきたいと思います。
本研究を行うにあたり、(e)大阪大学大学院理学研究科生物科学専攻の山田桃子教
授に A と B の遺伝子を含むプラスミドを供与していただき、佐藤太郎准教授に実験に関する貴重なご助言をいただきましたことを感謝いたします。
(f)ご静聴どうもありがとうございました。

問

下線部分 (a)〜(f) を英訳せよ。